THE 1927 `FIVE, AYEAR AHEAD oFANY OTHER SET!(see within)

Edited by Monthlyernafd E.Jones Vo1.4,No.22. November1926.

IN THIS ISSUE

Winding the long - wavelength coils,,Stabilising the set, etc., etc.ie If/

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Wireless Magazine.Arovember/92.6

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WirelessMagazine,Novembert92

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"Amateur Wireless "HAND OOKS

each 216 netLoud -Speaker Crystal SetsHow to Make and Manage ThemProvides working instructions for building a number of highlyefficient crystal sets ; making an attachment for simple connectionto existing wireless set , ..nd designs for crystal sets embodyingthe crystal loud -speaker system.

Perfect Broadcast ReceptionBy Ernest H. Robinson (5Y M)

Explains how most sets fall short of the ideal and how toobtain perfect reception. Is virtually a popular exposition of themain problems of transmission and reception. Very valuablealike to listeners and experimenters.

The Wireless Man's WorkshopBy J. Hartley Reynolds

Written by a practical home constructor, this book-containingmuch useful wireless information-enlightens readers on theselection and right methods of using the tools and materialsused in constructing wireless sets.

The Practical Wireless Data BookThe intelligent novice, and particularly the home constructor andthe keen wireless amateur who is always rigging up differentcircuits and experimenting for progress, will find this Data Bookextremely helpful.

In course of preparation

Wireless Faults and How to TraceThem By W. D. KendrickTells how to locate and remedy faults-fading, weak reception,and bad functioning generally. Fully illustrated with practicaldiagrams, circuits, etc. A perspicuous and most useful book.

All About the Wireless ValveShows how to choose a valve to meet special requirements-high-frequency amplification, detection and either low -frequencyor intermediate -frequency amplification ; how the valve hasdeveloped. Full of data and practical hints.

The Practical "Super -het" BookExplains what the Super -het is, what it does, how it works, andhow to build up a number of super -het sets (some of themAmerican, and others made of tested, British ;made components).

Of all Newsagents and Booksellers,2/6 net each, or 2/9 post free fromthe Editor, "Amateur Wireless,"La Belle Sauvage, London, E.C.4.

each I /6 net

Simple Valve Receiving SetsAnd How to Make ThemCONTENTS : A Single -valve Set with Basket -coil Tuner ; A Single.valve Set with Slide Inductance ; A Single -valve Autodyne ReceivingSet ; One -valve Variometer Set ; A Portable Single -valve Set ; Addinga Valve ; A Two -valve Set ; A Three -valve Amplifying and DetectingUnit ; The "Amateur Wireless" Unit Set; An Improved Unit Set; Index.

Crystal Receiving SetsAnd How to Make ThemCONTENTS: A Simple and Efficient Receiving Set; A Single -slider Set;Set with Semi -circular Tuner; Crystal Set with Tapped Single Coil; ALoose -coupled Set; Set with Plug-in Basket Coils; Combined Crystal andValve Receiver; Some Miniature Receiving Sets; Crystal Circuits; flowCrystals Work; Making a Buzzer; Receiving C.W. Signals on a CrystalSet; Converting Low -resistance Phones ; The Morse Code ; Index.

Wireless Component PartsAnd How to Make ThemCONTENTS : Components and Their Varied Purposes; Crystal Detectors;Coils, Making and Mounting; Condensers; Variometers and Vario-couplers; Resistances or Rheostats; Transformers; Making a TestBuzzer; Index.

A Useful Series fog

Cassell

Wireless Telegraphy and TelephonyAnd How to Make the ApparatusCONTENTS : General Principles of Wireless Telegraphy; Some Informa-tive Experiments; Tuning and Resonance Explained; Transmission andReception; Various Detectors Explained and Described; ThermionieValves as Detectors, Amplifiers and Generators; Making a Single -circuitReceiving Set; Making a Complete Short-wave Receiving Set; Makinga Valve Panel for a Receiving Set; Making a Five -valve Amplifier;Wireless Telephony; Arrangement and Erection of Aerials; Index.

Wireless Telephony ExplainedCONTENTS: The Electron; Induction and Electro-magnetism; Wavesand How they Travel; Inductance and Capacity; Rectification; Amplification; Reaction and Beat Reception; Aerials and Earths; TransmissionSystems; Receiving Sets; Useful Fdrmuke and Data; Index.

Of all Newsagents and Booksellers1/6 net each, or by post 3d. extrafrom The Editor, "Amateur Wireless,"

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291

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202

The Duvarileak

The VariableGrid Leakthat remains

* variableNo Dubilier product is placed onthe market until we can be abso-lutely certain of its giving perfectlysatisfactory results in use.The Duvarileak has been in theexperimental stage for three years.The final result is that this GridLeak will show a smooth and uni-form variation of resistance fromzero to five million ohms. Moreimportant still, by successfully dis-covering a resistance element ofextremely hard surface and byarranging a ball -bearing contact(see inset) we have assured that thewear in operation will be negligible.This means that the Duvarileakwill, throughout its life, give a con-stant resistance value for anygiven setting of the dial.Like all Dubilier products theDuvarileak can be relied upon togive the utmost efficiency in service--it is, in fact, the perfect variableGrid Leak at last.As seen in the illustration it hasone -hole fixing and a dial scale bywhich the resistance may be set.The Duvolcon for Loud Speaker Volume control is thesame in appearance and price as the Duvarileak and issuitable for use with any Loud Speaker.

Price 7/6 of all Dealers.

13011BlIERADVERTISEMENT op THE DUBILIER CONDENSERCO. (1925), LTD., DUCON WORKS, VICTORIA RD..N. ACTON. W.3. 'TELEPHONE: CHISWICK 2241-2-3

E.P.S.228

Wireless Magazine,Mventhen1926

WtelcooM ne

for November, 1926

Vol. IV No. 22

PAGE

Under My Aerial. Halyard's Chaton the Month's Topics .. .. 299

When You Have Bought A Set .. 303

The World's Most Elegant Studio.By The Editor .. .. 304

Collecting the News by Wireless. ByDr. Alfred Gradenwitz .. 306

The International Set Competition .. 307

The Inverse Duplex .. .. 308

Trial by-Audition ! By J. GodchauxAbrahams .. 310

Special Albert Hall Broadcast Concerts 312

National Wireless Week .. 313

Novelties and New Apparatus .. 314

The Human Side of Broadcasting.By the Programme Director ofKDKA . .. 320

Microphones Do Not Respect Persons ! 321

Nat Lewin and His New Verrey'sDance Band. A Cartoon .. .. 322

Broadcast Education and Its Wond-rous Possibilities. By Mrs. H. A.L. Fisher .. .. 323

Simultaneous Talks Worth Listening324

Charging Your Batteries from A. CMains. By E. Blake .. 325

How the Moon Affects Transmission.By Dr. Fournier d'Albe 326

How Radio Helps Sport .. 331

Sandy's Wireless Party 333332

WaveletsWhat Are Series and Parallel Con-

nections? .. .. 334

Why You Should Use Square -lawCondensers ..

Not only a handsome picturebut a loud -speaker as well!

CONTENTSPAGE

The Chorus Girl's Electrical Voice ! 336Dressing Up in the Studio .. .. 337Wireless " Lighthouses " : How

They Help Shipping .. .. 338

HOME -CONSTRUCTOR SETSPAGE

More About the 1927 Five-The Set That is a Year Ahead.

Further information about thisalready famous WIRELESSMAGAZINE Set, which has re-ceived 60 stations on a loud -speaker 294

The Miniwave Two -Valuer.A Set for the Short Waves.

To facilitate the construction ofthis set a coloured Structographplate is given free with this issue. 315

The Cosmopolitan Nine.A Three -unit Super -het

How to build the low -frequencyamplifying unit, which can also beused wherever else an amplifier isneeded . . . . . . 327

A Combined Crystal Setand Wavetrap.A Useful Unit for the Valve Man.An efficient crystal set that canalso be used as a selective wave -trap in conjunction with a valve

340

Ten Cabinet Hints .. 339

335 A Cheap Set for Jim ! 343

Where to Put the Filament RheostatsImprove Your Reception ! One-.

two-, and three -valve amplifiercircuits........345

PAGE

344

Guide to the Best Valve Sets. Fullyillustrated ..

G B R-The Colonist's Link withHome

Broadcast Music of the Month

346

356

357

The Modern Wizard .. .. . 360

Too Much Wireless ? . 361

Prospecting 361

Radio San Sebastian .. .. 362

A Motto for Your Set ? .. . 362

Soldering without Groans ! .. 363

Sssh ! " Adventures at a Listening -in Party .. .. 364

Decorating Your Wireless Cabinets 365

On Unknown Wavelengths ! 366

What Readers Think of Our Sets 368

Gadgets, Hints and Tips .. 370

Wireless Femininities 372

Jottings on the Month's Progress 374

What the Reader Thinks .. 376

What the B.B.C. is Doing .. 378

The World's Broadcasting .. 380

Below the Broadcasting Belt .. 382

Questions Simply Answered .. 384

Continental Notes .. 386

Catalogues and Pamphlets .. 390

The Buyer's Guide .. 392

Announcements.-The WIRELESS MAGAZINE, edited by Bernard E. Jones, is published about the 25th day of themonth, and fears the date of the month following. Technical Adviser : Sydney Brydon, D.Sc., M.I.E.E. OneShilling Net. Subscription rates are 15s. 6d. a year, roost free; Canada, I3s 6d. a year, post free. Contributions,accompanied by stamped and addressed envelopes, are invited. All editorial communications should be addressed to The Editor,WIRELESS MAGAZINE, La Belle Sauvage, London, E.C.4. Subscriptions should be addressed to The Publisher, WIRELESS MAGAZINE.

Registered at the Genera' Post 0,654e for transmission by Canadian Magazine Post.

293

Wireless Magazine. lthvemben 1926 I

911ox aboutthe 1927 Five-THE SET THAT IS A YEAR AHEAD !

General Hints on Operating : : Making Long -wave Coils : : Use ofSpecial Formers : : Adjusting the Neutralising Condensers : :

Economising in High Tension

Great interest. was taken.in the 1927 Five at the National Radio Exhibition held at Olympia.

THE interest aroused in the 1927Five has exceeded even our ex-

pectations At the National RadioExhibition held at Olympia in Sep-tember the original receiver was onshow, and our technical representa-tives had all their time taken up ingiving particulars of the new receiver.

Details RepeatedThis month we are giving ag'ain,

in brief, constructional details for thebenefit of those readers who wereunable to obtain the October issue,.which was rapidly sold out

Those who prefer to wind their owncoils may obtain specially cut eboniteformers from the British -Ebonite Co.,Ltd., of Hanwell, Middlesex.

These formers con-sist of a cylinder ofebonite along thesurface of which,parallel to the axisof the cylinder, aresix projections of tri-angular section,equally spaced roundthe circumference ofthe cylinder. The dis-

tance between diametrically opposingprojections is 3in.

A set of three of these formers isobtainable for both the short andlong wavelengths.

To one end of each of the formersa circular ebonite base is screwedinto which the four pins are inserted.The spacing of these pins is differentfrom the original Magnum coil inthat the distance between the twopins on the major axis is iin. insteadof zin. The length of the minor axisis tin. -as before.

These measurements are the samefor the sockets mounted on the threeebonite platforms. Sketches aregiven showing the dimensions,method of winding and tapping thecoils for broadcast wavelengths.

For longer wavelengths (from abouti,000 to 2,000 metres) another set ofthree coils is required. In construc-tion and the method of winding andtapping, the long -wavelength coils areslightly different from those alreadydescribed for short broadcast wave-lengths.

294

The long -wavelength aerial coil,for instance, is tapped at only oneportion of the winding and in thecentre. Connections for the windingto the pins are therefore differentfrom those of the short-wave aerialcoil. The former is 4iin. long, andis wound with 230 turns of No. 30gauge d.s.c. copper wire, tapped .atthe 125th turn.

Coil ConnectionsConnections from the two ends of

the coil and the centre tapping areshown in one of the sketches. Thissketch shows an elevation of the coiland a view of. the base (not the plat-form. on - which the sockets aremounted) looking at the bottom ofthe coil. The con-nections are broughtthrough small holesdrilled beside each ofthe four pins andsoldered to the latter.

It is very impor-tant that these con-nections are correct,and it will be notedthat the two pins on

.00025

SCREEri

Diagram showing how grid bias canbe applied to the H.F. valves.

the minor axis are joined togetherand to the top turn of the coil.

In order to keep the turns of wireIn position, it may be advisable toapply shellac varnish lightly over thecompleted winding.

Each of theanode coils iswound on a similartype of former,41in. long. Thewinding consists of300 turns of No. 32d.s.c. wire tappedat tooth and 2oothturns. Note thatin the case of theselong -wave coilsthere is no spacingbetween each of thethree sections, andthat the coil iswound straight onleaving loops at the tappingfor connecting to the pins.

Sketches are also given showingthe construction, winding, and con-nections of these coils, of which twoare required.

The Magnum coils, which may beobtained -ready for use, have thesame winding specification, the onlydifference being in the spacing of thepins.

The constructor has thus twocourses open to him. He may eitherbuy the coils already made to ourspecification, or else he may windthem for himself on the Becolformers, as illustrated.

We would point out that as thecoil platforms for the bought coilsare different to those for the Becolformers, the constructor must notbuy one set of coils and make theother set. He must buy both ormake both sets.

So much for the coils. Now wehave some remarks to make concern-ing the neutralisation of the H.F.valves.

In the specification of the valvesgiven in the last issue of the WIRE-LESS MAGAZINE a misprint occurred

Photograph of the 1927 Five,showing its handsome appearance.

points in the nomenclature of one of thevalves. The last valve-that is, thesecond L.F. amplifier-should be aDE5A, and not a DE5B as stated.

By the way, those who do notdesire to use a 6 -volt accumulator

WirelessMagazineArovemben.i926f

e.

.4 I

EBONITE PLATFORM3%2" DIA . X 4: THICK

Dimensions of the base for mountingthri home-made short- and long -wave

coils wound on Becol formers.

can use Cossor Point One valves,which need only a 2 -volt battery.For the high -frequency stages twored -band valves should be used; forthe detector a black -band valve; andfor the low -frequency stages two

Stentor Two's ora black -band anda Stentor Two.

If these valvesare used the totalcurrent consump-tion will be only.55' ampere.

Other valvesmay, of course, beused with as goodresults, only it mayb e necessary t ovary the tappingpoints on the twoH.F. anode coils.

If neutralisationis found to be at all difficult,experiments should be made inthe following order :-Take thetwo low -wavelength anode coils andwind the top and middle sectionsof the formers (see p. 594 of the

Cabinet and baseboard (UnicaCabinet Co.).

Grained ebonite, panel, 271in. byTin. (American Hard Rubber orBecol).

Terminal strips, loin. by ain. and6in. by tin. (Siemens or Trelleborgs).

12 engraved terminals (Eastick orBelling and Lee).

.0005-microfarad variable con-denser (Igranic-Pacent S.L.F. type orOrmond, G.E.C., Raymond S.L.F.).

Two .00035-microfarad variablecondensers (Igranic-Pacent S.L.F.type or Ormond, G.E.C., RaymondS.L.F.).

Three 4in. inahoganite dials(American Hard Rubber).

LIST OF COMPONENTSREQUIRED

Panel -mounting milliamtneter,reading o -to or 20 milliamperes(Sifam).

Set of special coils made to ourspecification complete with baseboardmounting (Burne-Jones), or home-made coils as described in this issue.

Four aluminium shields (Burne-Jones).

Two neutralising condensers(McMichael).

Five baseboard -mounting anti-microphonic valve holders (Lotus orBenjamin, Burndept).

Five fixed filament resistors(Burne-Jones).

Two .00025-microfarad grid con-densers (T.C.C. type SP or Dubilier,Mullard).

One 3-megohm and one 5-megohmgrid leak (Ediswan or Dubilier,Mullard).

Two jacks (Igranic-Pacent types65 and 66).

One plug (Igranic-Pacent Auto -plug).

Three 1-mi crof arad fixed con-densers (Dubilier-Mansbridge orT.C.C.).

Two L.F. transformers, ratios2.7 tot and 4 to (Marconiphone).

.0003-microfarad fixed condenserwith clips (Wates K).

295

CONSTRUCTIONAL DETAILSOF THE ALREADY FAMOUS

1927 FIVE-THE SET THAT IS A YEAR AHEAD!

Ilm

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I III

14 5WC,. COPPER"" WIRE SOLDERED TO

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LOW -LOSS FORMER

[-Wireless Magazine. November:19261

/ic,R04E FORj,1 PLATE (0Mf5CTIIIG

5100554

N

()-F'i8F7)1fllfrj."BA5EBOMIDn'

5

(Above) -- Dimen-sions of the aluminiumscreens which play nosmall part in makingthe 1927 Five as

efficient as it is.

(Below). - All thescreens are earthed.This diagram showshow they areconnected together

electrically.

ALLWINDI20 D.C.C.

Short-wave Aerial Coil.

A LIST OFCOMPONENTSAPPEARS ONPAGE 295

(Above). - This diagramshows the secret of theefficiency of the high -frequencyside of the 1927 Five. TheH.F. coupling is a simpleadoption of the Wheatstone -bridge principle and gives

perfect balance

BACK

'4`(Below).-Details of the home-madeshort-wave coils wound on Becol formers.The base for these coils is shown on page 297.

(Above).-Four aluminiumscreens are cut and fixed

in position as shown.

1,'16

(Left and below).-Dimensions of thecabinet and baseboardof the 1927 Five. Thepanel and all the

components are fixedto the baseboard,which slides into thecabinet from the back.

6

3 DIAI MINI110

101111.91141111111M11101

} 30 TURNS

30 TURNS

30 TURNS

ALLWIN MKS28 D.C.C.

SIIIII=pIIt1tSI1MliilWl

LOW -LOSS FORMER

Short-wave Anode Coil.

296

Wireless Magazine, Novemben192pj

This photograph shows clearly the arkangement of the components of the 1927 Five on the baseboard.

250 TURNSTAPPED ATTHE 125T2'

WIND WITKN° 30 D5C.

Details of the Long -wave Aerial Coil.

STATIONS HEARDWITH THE1927 FIVE

In addition to the fifty short-wavestations heard (particulars were givenon page 195 of the last issue) ten high -wavelength broadcasting stations havealso been received at loud -speakerstrength on the 1927 Five :-Soro Radio -ParisKarlsborg NorddeichKimigswusierhausen AmsterdamMoscow HilversumDaventry Ryvang

The long -wavelength anode coils specifiedwill not tune down to less than about 1,150metres, but by winding these coils onformers having the same dimensions, butconsisting of 240 turns of wire tapped atat the 80th and 160th turns, stationshaving a wavelength round about 1,000metres (surh as Hilversum) may be receivedat the sacrifice of Norddeich and Amsterdam.

3"DlAw.-----...oinnwie

300 TURNSTAPPED ATTHE 100"

200"TURN.WIND MTNri° 32 D5(

eausimmem moms as

Details of the Long -wave Anode Coil.

REL11.5

C

Circuit diagram of the 1927 Five-by means of the jacks either four or five valves can be used at will.

297

[ Wireless Magazine. Notrmben 1926

Ya.5

R0515000,

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PANEL 27 Ya..-X 7

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BASEBOARD 27 Va..% 9.

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marked a should first be

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GO LT'- up, all those terminals

6 b

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00555

Layout and Wiring Diagramof the 1927 Five. In wiring

connected together with one wire or as few wiresall those marked b,

October issue) each with 3o turns ofwire as specified, and wind the lowersection with about 40 turns of wire.the connections to be made exactlyas shown in the sketch on p. 194.Now place the coils in position and" try them out."

If neutralisation is still difficult,reduce the number of turns on thelowest section five at a time, each

and so

b

b

hi^

MOVIOG

.0005

as possible, and thenon, until all the connections have been completed.

time trying the coils for perfectneutralisation. It may be found thatthe number of turns required on thelowest section is very small, and, in-deed, the receiver will work verysatisfactorily with the lowest sectionreduced to five turns.

The number of turns specified inthe original article were found towork satisfactorily With the valves

mentioned, but even here, as no twosets will be identical in the wiringand, possibly,' the components used,the number of turns on this lowestsection may have to be reduced.

A five -valve receiver will cause aconsiderable drain on the H.T. bat-tery, but this may be counteracted toa certain extent by applying a nega-

(Continued on page 307)

Another photograph showing disposition of the components of the 1927 Five.298

Wireless Magazirie, November./

Halyard's Chat on the Month's Topics

Getting Down to ItHOW do you intend to tune -in the

relay stations on their newwavelengths below 300 metres.?

If you use plug-in. coils, I daresayyou will consider adopting the simpleexpedient of buying a new coil inorder to get down to these unfamiliardepths.

Failing the purchase of a new coil,perhaps.you contemplate accomplish-ing the same thing by replacing yourpresent tuning condenser with one of

Getting down to it

smaller capacity, or by altering thewiring of your set so that your tuningcondenser is in series with your coilinstead of in parallel with that coilas previously.

If you have not Yet bothered aboutgetting' down below 30o metres be-cause of the trouble or expense oruncertainty as to whether the newwavelengths will be' adhered to, I

wonder if you would not like to trythe very simple method of placing asheet of metal near your smallestcoil.

You know that if you place a sheetof metal or a shorted coil near to aninductance coil the inductance valueof that coil is lowered, and that thishas the effect of lowering the mini-mum wavelength obtainable withthat coil.

For example, suppose that yoursmallest coil gives you a minimumwavelength of 300 metres. Then, byputting a sheet of metal close up tothat coil, you will get a minimumwavelength of 28o metres, say.

This seems to me to be the bestscheme while doubt remains as to thepermanency of the new wavelengths.

ir as So

Daventry's New AerialHave you noticed any difference in

your reception of 5XX since the newaerial at that station was put intocommission ?

I have not seen this new aerial yet,but, in one account I read of it, thenew aerial was described as heing V-shaped with a downlead at each end.

What do you make of this descrip-tion? I think the chances are thatthe V has a horizontal top to it, andthat a better description of the aerialwould be that it is shaped like theGreek letter A.

The old aerial was T-shaped witha downlead at the centre. You will,perhaps, remember that the oldaerial collapsed under the weight ofsnow which accumulated on it duringa snowstorm early one morning lastDecember.

There are two interesting questionswhich may be asked about this newDaventry aerial, Will it prove -to beof greater mechanical strength andtherefore less likely to' break downunder weight of snow? it givegreater efficiency in transmission?

The answer to the first of thesequestions will, be no less interestingto wireless engineers than the answerto the second question will be to us.

THINKING OF BUYINGA NEW SET ?

Then turn to page 346 andread through our " Guide to

the Best Valve Sets."

299

At OlympiaHere is a special question I should

like to put to those who were for-tunate enough to see the wireless ex-hibition at Olympia.

What was the most wonderfulthing you saw at the National RadioExhibition?

Was it a receiving set in a cabinetde luxe, a variable condenser or aloud -speaker? Was it a high-tensionaccumulator, a crystal, or the modelof Signal Hill, Newfoundland? Was

Was 't a valve?

it a coil, a television set, or a foldingframe aerial? Was it a transformeror a terminal?

It might have been any one of thesethings, or it might have been one ofthe hundreds of other wonderfulthings to he seen in the exhibition.,

Shall I tell you what, I thoughtwas the most wonderful thing in theexhibition?

It was none of those things men-tioned above. fact, it wasn't apiece of wireless apparatus at all.

It was the long queue of peoplewaiting to file past the windows of theB.B.C. studio.

There must have been some hun-dreds of people in that queue at times,and I am sure it must have takenthe best part of half -an -hour to reachthe window after joining the queue.

Could anything be more indicativeof the interest taken in broadcastingthese days?

By the way, what happened to allthe armchairs on the stands when theexhibition closed?

Wireless Magazine. Not wither 1926

Under My Aerial (Continued)

Uniform PronunciationI hope you are keeping an eye (and

an eat) on the efforts of the.B.B.C.to standardise. the pronunciation ofcertain catchy words in our language.

What amuses me vastly about theinstructions in pronunciatibn whichwe see in print froni time to time is

Uniform" pronunciation.

the curious contortions in . spellingwhich have to be made in order toconvey to us the right and properpronunciation of the tricky word.

For instance, it 'really appeals tomy sense of humour to be told thatthe B.B.C. standard pronunciation ofthe word acoustics is acoosticks andnot acowsticks. Isn't it just delight-fully puzzling to see the right and thewrong pronunciations together?How can one remember which iswhich?

The B.B.C. announcers and theirlisteners are not the only people whocome an occasional cropper over thevagaries of pronunciation. School-masters and examiners know allabout such things as the followingincident will show.

Last summer, in a written exami-.nation of some thousands of schoolchildren in a northern county, theexaminer asked the children to writedown a word pronounced in the sameway as dew but spelt differently.The expected answer was, of course,due.

In that particular counts, however,dew is pronounced do, and, to theexaminer's surprise, he got do forthe answer. Still, the little folkfound great satisfaction in being ableto dew the question in their own way.

Weather and Wireless" Why is it that so much atten-

tion is being paid in America to theproblem of the effect of weather onwireless? " I asked my meteoro-logical friend the other day.

" Why ! is it? " he asked." I should think' it is. Why !

articles on weather and wireless haverecently appeared in two American.wireless periodicals and in one Ameri-can scientific journal. Rather a curi-ous coincidence, is it not, 0 FurtherOutlook ? "

" Possibly it is. Do the Writers ofthese articles claim any definite. re-lationships between weather andwireless?

" Not likely. ' They know too muchabout the weather for that. Theymake several interesting suggestions,however."

" As for example? "" That reception is clearest and

strongest when the received wavestravel at right angles to the isobars.I should appreciate an explanation ofall this."

" You know what a right angle is,don't you? "

" Yes, sir."" And you know what an isobar

is? "" Well, I once did know, but

Look here,.can'tyou. give me an ex -

Travelling parallel to the (iso) bar.

planation without using the wordisobar?"

" Oh, yes, quite easily. The idearoughly is this. If the received wavestravel at right angles to the mainwind current, reception will be at itsbest. For instance, with a south-wdst wind over these islands, recep-tiOn would be better. from the north-west or south-east than from thesouth-west or north-east."

"-Thank you. That's clear enough.How about this? Fading occurswhen the received waves travelparallel to the isobars."

" Roughly speaking, parallel to theisobars would be dead up or downwind."

" So that when receiving theFrench stations in England, fadingwould be worse when the wind wassoutherly than when the wind waswesterly? "

" Provided your American writersare not barking up the wrong tree."

" Just one more question, old fel-low. One American writer says that

300

atmospherics are more prevalentwhen the isobars are far apart.Translate, please."

" He means the less wind there is,the more atmospherics there will be."

" I think he is right over that.There is very little wind before 'athunderstorm at times locally."

A Useful Loud -speaker" What do you think of the new

Marconi loud -speaker, George? " I

asked that man of wireless wisdomone evening last week.

" To which particular loud -speakerdo you refer? " he asked.

" The one with .the ten -milerange," I replied.

" Oh ! that one," said George." Well! as a loud -speaker I cannotsay that I am charmed with it. Yousee I should hardly care about theprospect of a ten -mile walk everytime I wanted to listen to my ownloud -speaker."

" George, you - "" But as a regulator for those of

us who have to catch trains in themorning I consider it has great possi-bilities."

" How would you use such a -loud-speaker for that particular purpose,George? "

" I should install one at every rail-way station where busy men of busi-ness, such as myself, have trains tocatch. The top of a signal mastwould be an excellent position for theloud -speaker. I should place themicrophone in the station -master'soffice, and put the station -master incharge of the spoken word. Moststation -masters would be glad of a

A useful loud -speaker !

definite job of work, you know.""How would the thing be used,

George?"" The station -master would an-

nounce through the loud -speaker theposition of the incoming train so thatone could regulate one's speed to thestation. A capable man would givesuch announcements as these :--

1relessMagazme. Novembers 1926 i

Halyard's Chat on the Month's TopicsSignal just dropped for the 8.54 up.8.54 now passing under distant

bridge.8.54 now entering station.Plenty of time this morning. Bags

of luggage and two fat women to bepushed on board.

Hurry up the scratch men ; guardabout to waggle his flag." George, it's one of the brainiest

notions you've ever been struckwith."

" Thank you kindly, sir."

44, CA New Hygrometer

Just over a week ago I was com-pelled to put up a temporary aerial.My new permanent aerial is ready togo up, but I am not at all anxious totake down my temporary aerial, for ithas proved to be one of the besthygrometers I have ever seen.

I have borrowed that word hygro-meter from my meteorological friend.He has rather a choice collection ofbeautiful words of that kind, and heis very generous with them.

A hygrometer is an instrumentwhich indicates the dampness of theatmosphere, and I daresay you arequite familiar with that simple hygro-meter known as " Jacky and Jenny,"in which the " old woman " comesout when the weather is going to befine, and the " old man " comes outwhen the weather is going to be wet.

My temporary aerial is as good aweather indicator as any " Jacky andJenny." The reason is this. Oneend of the aerial is attached to aninsulator which I placed at the centreof a length of rope some twenty-fivefeet long. This rope is at rightangles to the aerial wire, one end ofthe rope being fastened to the frameof a bedroom window, and the otherend to a tree.

A choice collection of words.

When the air is damp, this ropetightens and pulls the aerial wiretight. When the air is dry, the ropeslackens and causes the aerial wireto hang quite loosely. About themiddle, the aerial wire runs quiteclose to a tree, and I can easily judgethe height of the aerial wire by abranch of the tree. I am sure there

is a variation of at least a foot in theheight of the aerial wire just whereit passes the tree.

I have got into the way of lookingout of my bedroom window at theaerial wire first thing each morning.If the aerial wire hangs loosely, I ex-pect a fine day. If the aerial wire isas high and tight as it can be, I amcertain it will rain before the day isout.

4Knobs

Do you think it is an altogethergood thing that we should be continu-ally striving after the further simpli-fication of our wireless sets?

These drastic reductions in thenumber of controls on our panels areall very well in some ways, but Iwonder who gets the most enjoymentout of the manipulation of his set,the one -knob man or the multi -knobman?

This simplification of our receivingsets may have a tendency towards

A one -knob man

making wireless reception a little tooautomatic. The one -knob man cannever experience the pleasure of theexperimenter who is able to manipu-late the controls of his set as skil-fully as an organist manipulates thestops of his organ.

A man may be content for a whilewith a press -the -button set, but thechances are that, when he becomesthoroughly fascinated with wireless,he will want a better and moreelaborate form of instrument.

It is said that knobs on a wirelesspanel are quite out of fashion. I donot believe this. Why when I wasat the Olympia wireless exhibition,wherever there was a knob or a dialto be turned on one of the stands,somebody was turning it. I nevergot a turn anywhere.

I have seen many a man kept quietfor hours with a few knobs on apanel, turning and turning them againand again, and never getting a singlesignal. There's a lot to be said, onthe quiet, for knobs.

301

Another CondenserWhen the so-called straight -line -

frequency variable condenser ap-peared on the English market, didyou not think that the wireless manu-facturer had exhausted all possibletypes of this particular instrument?

Those of us who started wireless a

Straight-line frequency.

few years ago have passed throughthree successive stages in variable -condenser design.

First we had the now obsoletestraight -line -capacity condenser withits semi -circular vanes. Then we hadthe square -law or straight -line -wave-length condenser with its peculiarly -elongated vanes. Lastly, we havehad the straight -line -frequency con-denser with its still more elongatedvanes.

Each of the three types mentionedhas its own particular disadvantages.In the earliest type with the semi-circular vanes the stations werecrowded together at the lower end ofthe scale on the dial.

In the most recent type, thestraight -line -frequency condenser, thestations are crowded together at theupper end of the scale on the dial.Indeed, one of our leading manufac-turers of variable condensers told meat the exhibition that he had decidednot to make a straight -line -frequencycondenser because such a condensermerely transferred the crowding fromone end of the dial scale to the other.

The straight -line -wavelength orsquare -law variable condenser hasbeen described as a useful compro-mise between the other two types.

One would have thought that, fromtheoretical considerations, all pos-sible types in condenser design hadbeen used up, but it is not so. Therehas appeared on the American marketa fourth type to which has beengiven the name, in one case, of the" midline " condenser, and in anothercase, the straight -line -tuning con-denser.

It is claimed for this new type thatit possesses important advantages.

Wireless Magazine. A'ovrmber 1926

Under My Aerial (Continued)

Oh! MurderA schoolboy acquaintance of mine

recently had a disquieting experienceof wireless, an experience which, Ithink; would have tried a good manyof us.

Coming home one evening hefound the family out and the houseall locked up. Not knowing quitewhat to do with himself if he re-mained out of doors, he decided toact on the bright idea of getting intothe house and. listening -in with hiscrystal set until the family camehome.

To get into the house, he climbed

" Oh murder."

up an outbuilding. From the roof ofthis outbuilding he jumped on to aflat piece of 'roof over the scullery.This flat roof gave him access to anopen bedroom window and the rest

The boy came downstairs and wentinto the room where he had left hiscrystal set tuned -in on Daventry. He.placed the phones over his ears andlistened with expectancy. This iswhat he heard :-

Oh! what shall I do?.I've killed him.I've killed him.

That was all the boy stayed tolisten to. Would you have stayed.tolisten to more of that kind of thingif you had been all alone in a locked -up house?

it tA Picturesque Loud -speaker" George, old man, I very nearly

fell this afternoon."" Banana skin or orange peel ? "" No, not that kind of fall, George.

I was sorely tempted to buy a newkind of loud -speaker."

" But you've got three loud-speakers already: Where do youwant another one for, the bathroomor the conservatory? "

" I really do not want anotherloud -speaker, George, and what ismore, I cannot afford another onejust now. All the same, I very

nearly bought that excellent loud-speaker this afternoon."

" What sort of a loud -speaker wasit? "

" One of the new picture loud-speakers. ' Do you know, George,when -went in that shop I did notknow where the music was comingfrom."

" You should have taken thecotton -wool out of your ears."

" Don't be silly, George. Youwouldn't. have located the loud-speaker any more quickly than I did.I was astonithat the loud

shed when I was told-speaker was the .pic-

ture."" Every picture tells a story, you

know."" That one told its story very well,

anyhow. Thecellent. Ther

reproduction was ex -e was a pretty picture

fixed on a gilded canvas mount, andthe loud -speaking mechanism was be-hind the picture, the whole thingbeing fitted in a pleasing gilt frame.

" Couldn't you tell it was a loud-speaker by. the leads to it? "

" No, the leads were the cords -bywhich the picture was hung. I neversaw a loud -speaker more skilfullydisguised."

Every picture tells a story."

-SunnyWe I% ro.e._ TODAY

r,LINA

" What -sort of a picture was it? "." Oh ! 'a pretty little country scene,

stream, flowers, trees and hills andthat sort of thing. Possibly it would

ALWAYS GOOD

we are yet doing our best to make theChristmas Number of the WIRELESS

MAGAZINE even

BETTER.

In the Christmas special issue publishednext month will be found all the usualpopular WIRELESS MAGAZINE features and

many special articles as well.

In fact, of all Christmas Numbers thatof the WIRELESS MAGAZINE will be

THE BEST.

302

not be quite your idea in pictures.What do you think would be the bestpicture for a picture loud -speaker,George? "

" Hum-er-The Owl by er-Whistler, or er-Sunset over theKnobs by Turner, or-er-Cracklesby Jove, or-er-er

" That will do, George, thankyou."

0 .0 *My Surgery

It's all very well helping somebodyelse to make a wireless set if it would

iwaexT

Wireless invalids.

only stop. at that. My experience,though, is that if you ever do suc-cumb to persistent requests for helpin the building of a set, that set willcome back to you sooner or later fortest and repairs.

At the present moment there aretwo wireless invalids in my surgery,one a three -valve set and the othera four -valve set.

I do not,know when I shall be ableto give the'Se invalids my attention,and, really, I am not anxious to havea go, at either of them. When youstart on a job of that kind, you neverknow whether it is going to take youan bout' or a week.

From what has been told me of thesymptoms of these two crocks, I havea shrewd idea that they are bothsuffering from the same complaint,namely, a burnt -out primary in thesecond low -frequency transformer.

If such turns out to be the case itwill be a simple matter to effect acure.

The funny thing about these twoinvalid sets is that their owners haverecently gone in for high-tensionaccumulators, and I have been won-dering what fool tricks they have beenup to with those high-tension accu-mulators to burn -out the primaries oftheir transformers.

Have you heard of any similaroccurrences amongst your wirelessfriends? HALYARD.

Wireless Magazine.Nomnber1926

NOWADAYS commercial re-ceivers have reached such a

high state of efficiency and reliabilitythat very little wireless knowledgeindeed is required on the part of theoperator to get satisfactory results.In fact, all that the purchaser of anup-to-date set need know is sufficientto enable him to connect up thevarious batteries and to tune the setto the stations it is desired toreceive.

A wireless licence should, ofcourse, have been obtained at apost office before the set was pur-chased. This will have cost tenshillings-surely not a very largesum to pay for the privilege of lis-tening to the broadcast programmesevery night for twelve months.

Whatever the type of set bought,an aerial of some kind will be re-quired. Some sets will work with aframe aerial-a number of turns ofinsulated wire wound on a woodenframe-but in the majority of casesthe set will be provided with twoterminals, one of which is to be con-nected to an elevated wire and theother to earth:

In this latter case the position,length, and height of the elevatedwire-the aerial wire-will have agreat bearing on the subsequentperformance of the set, and soshould be given careful con-sideration.

Unsereened AerialPreferably the aerial should be

erected c,itside the house and as faraway from any buildings, trees,etc., as possible. The wire shouldbe as high as possible above theground for best results, and must becarefully insulated. The best wayto erect an outside aerial, in themajority of cases, is in the form ofan inverted letter L.

That is, the aerial should consistof a more or less horizontal portion

stretched between a support on thehouse and a mast, tree, or other con-venient object some distance away,and a more or less vertical portionleading from the house end of thehorizontal part to the aerial terminalof the set.

The aerial should be insulated at

You find it difficult to decide on what

particular set to buy Then why not turn

now to page 346 and Yeast through our

" Guide to the Best Valve Sets- ?

When you .have bought a set there are

certain important preliminaries to be

attended to before you can listen -in -this

article explains what these preliminaries are

and how they can best be carries! out.

the far end, at the point where thedown -lead joins the horizontal por-tion, and at the point of entry intothe house.

If an outside aerial is impossible,an indoor aerial may be erected.This should consist of a covered wire(not essential in the case of an out-side aerial), and the same generalprinciples with regard to height, etcshould be observed. The totallength of the aerial must not exceedrap ft. as measured from the aerialterminal of the set to the far end ofthe herial. If space does not permitof a single wire of this length to beerected, two wires, spaced at least6 ft. apart, may be used.

Note that the limit of aerial lengthapplies to the aerial as a whole, andnot to the amount of wire to be used.

The earth connection may consistof a zinc or copper plate buried be-neath the aerial and connected to theearth terminal of the set by a lengthof well -insulated wire of a gauge not

303

smaller than that used for the aerialproper. Alternatively, this earth -lead may be soldered to a mainwater -pipe near to the point at whichit emerges from the ground insteadof to a buried metal plate.

Having connected up the aerialand earth, the batteries must now beattached to the set. There will beat least two batteries, perhaps three.If the set is provided with only threebattery terminals, the + (positive) ofthe H.T. battery is to be joined toone, one side of the L.T. battery toanother, while the remaining ter-minals of H.T. and L.T. batteriesare both to be connected to the third.The terminals on the set will bemarked. More usually there will becomplete sets of terminals for bothH.T. and L.T. batteries.

There may be two terminalsmarked L.T. and - (negative)respectively, one marked H.T. -and one or more marked H.T.If there is more than one H.T. +terminal, each of these terminals isto be connected to a point on theH.T. battery, the best points for con-nection being found by experimentwhen the set is in operation. All theH.T. + terminals may be connectedtogether and to the + end of theH.T. battery until a station has beentuned -in.

Grid BiasThere may possibly be two other

terminals marked G.B. (grid bias)and G.B. -, in which case a

small battery with a voltage variablebetween zero and six or nine volts(in is -volt steps) is to be connectedto them.

Having inserted the valves in theirsockets (and also the coils, if theseare of the plug-in type), and havingconnected up the phones, an attemptmay be made to tune -in the local

(Continued on page 307)

Wireless Magazine. November: 1926

Rehearsal studio for artists at WSAI, Cincinnati.

WHEN I visited .WSAI in April of thisyear, the studio was in course of comple-tion. Mr. P. A Green; the Studio Director,

presented me, I remember, with a souvenir-apacket of beautifully printed playing cards-as areminder that WSAI is owned and operated bythe United States Playing Card Co., of Cincinnati,U.S.A.

The studio is two or three miles from the centreof the city and is a part of the conipany's worksand offices, while the five -kilowatt transmittingstation is several miles away in the village ofMason.

Finest Collection of Playing Cards.WSAI houses the world's finest collection of

playing cards and card literature.' ' Playing cardsfrom countries all over the globe have been brought

- within its walls, and exhibited in glass cases, to re-ceive which the studio has been specially designed.

There playing cards go back very manyhundreds of years, represent most of the countriesof the world, and their value must be reckoned inscores of thousands of pounds.

The reception rooms for artists and their friendsare graceful and ample, perhaps the finest broad-casting reception rooms in the world.

Their comfortable furniture, built-in cases, andoriginal painting on the. walls (designed in the.first case for the backs of playing cards) serve 'tobeguile the artists during . their somewhat anxiousand always nervous moments when waiting tobroadcast.

WSAI puts out quite a special programme. Itre -transmits most of ,the important New Yorkchain' prograinmes, as do some 15 or 18 otherstations in the United States, and in addition ithas its own concert arrangements and broadcastsprogrammes of high quality and. not a littleoriginality, in which work Mr. Fred Smith (whoas an author has made his bow to the readers ofthe WIRELESS MAGAZINE) regularly plays a part.

By 'the way, we have heard the grumble that2L0 will notbe really complete until it has alight -refreshment bar for the convenience 'of 'artists.No such sin of omission can be debited -to WSAI.

A Cafeteria.In the same building ,and within a few yards of the

entrance to the studio, is a cafeteria (help -yourself-and -pay -as -you - gorestaurant) capable of ofia8 I re'.seating severalhundred people.

304

Wireless Magazine, Novrmber1926

(Toe)-Reception room at WSAI ; note the collection of historical playing cards ranged in frames round the walls. (CENTRE)-The controllercan watch what is going on in the main studio through a glass window. (BoTTom)-Main concert studio at WSAI, Cincinnati.

305

Wireless Magazine 'November: 1926

@Reding, Vws byV, firelessAn Account of a Receiving Station Owned and Operated by aGroup of German Newspapers. By Dr. ALFRED GRADENWITZ

H.T.VOLTMETER

LONG-AND SHORT-WAVE SWITCH

PITCHSELECTOR

PRIMARY TUNER300 to 3,000

METRES

SECONDARYTUNER

300 to 3,000 METRES

SPARE COILS

WHAT is probably one of themost elaborate receiving

stations in existence is to be found inthe Rudolf Mosse building in Berlin.From this office of the Mosse Publish-ing Co. are issued the BerlinerTageblatt and some other dailies. Thestation is intended for the direct recep-tion of press news by wireless tele-graphy from both home and foreigncorrespondents.

Separate PartsThe receiver comprises two separate

parts, one for reception on wave-lengths of from 300 to 3,000 metres,and the other for reception on wave-lengths of from 3,000 to 25,000metres. As can be seen from thephotograph, the whole of theapparatus has been accommodated ina mahogany desk, designed andinstalled by the Lorenz Co. Thedouble -wire aerial is T-shaped, beingapproximately 'so ft. long and sus -

THREE -VALVEL.F.AMPLIFI ER

CLOCK iL.T.VOLTMETER

PHONE SOCKETS

pended about 45 tt. above the root otthe building. Tungsten - filamentvalves are used throughout, the powerfor these being supplied by a 6 -voltaccumulator and a 50 -volt high-tension battery.

The arrangement of the mainreceiver can be seen from the photo-graph. It comprises two primarycircuits, one with a range of from300 to 3,000 metres and the other witha range of from 3,000 to 25,000metres. Each primary is made up ofthree interchangeable coils, tuned bya condenser with coarse and fineadjustments. Variation of the induc-tive coupling with the receiver iseffected by means of a knob on theleft-hand side.

Used in conjunction with these twoprimary circuits are two identicalsecondary circuits.

Should signals be too loud the in-tensity of the sound can be reducedby a device which effects artificial

306

AMPLIFIER SWITCH

VOLTMETER SWITCH

HETERODYNEUNIT

PRIMARY TUNER3,000 to 25,000

METRES

SECONDARY TUNER3,000 to 25,000 METRES

H F AMPLIFIER3.000 to 25,000

METRES

camping ot the aerial. Moreover,this damping device is also useful forpreventing objectionable self -oscilla-tion.

Included in the receiver is a one -valve high -frequency amplifier in-tended for reception of wavelengthsfrom 3,000 to 25,000 metres. Thisrange is covered in three stages.

C. W. ReceptionSo that undamped (continuous

wave) signals can be received a hetero-dyne unit is incorporated to producethe necessary beats. This unit is cali-brated for various ranges of wave-lengths, any one of which can beobtained at a moment's notice.

An interesting point about the low -frequency amplifier (which containsthree valves) is the pitch selector.Selection of a suitable pitch in thephones is effected by acoustic means.This is a great advantage in receptionas it enables the operator, by suitable

Wireless Magazine. Novemben1926

adjustment, to cut out a great deal ofinterference. It can be used to cutout entirely the sound of generatorhum.

Though an ample wavelength rangehas been provided it may happen thatthe adjustments for several stationslie so close together that separatereception of any particular trans-mission is difficult. This is remediedby working with preliminary andintermediate circuits and the pitchselector. In case reception should faileven then frame aerials are used inplace of the outside roof aerial.

For use with the frame aerials aspecial separate receiver has beeninstalled. This resembles the generalreceiver already described, but it con-tains three high -frequency amplifiersinstead of only one. Reception canbe carried out on the frame -aerial seteven when atmospheric disturbances(such as thunderstorms) are at theirstrongest.

More About the 1927Five (Continued from page 298)

tive potential to the grids of both IL F.valves. The way in which this isaccomplished is shown in the circuitdiagram of the two H.F. valves, andit will be seeilthat the negative ter-minal of a or 3 -Volt dry batteryis connected through the aerial coil(in the case of the first H.F. valve)or through the grid leak (in the caseof the second valve) to the grids ofthe valves.

This is a refinement which nor-mally is hardly necessary, but insome cases where high plate voltagesare used it may be found beneficial.

On p. 297 is a list of the long -wavelength stations received on the1927 Five. These were received, asbefore, at a distance of 7 miles westof 2LO, and the reception wascarried out on an outdoor aerial.

For short-wave reception, induct-ances should be built so that the turnsof wire are as self-supporting aspossible; condensers should be wellmade and without small pieces orbushes of ebonite to act as leakypaths for oscillating energy ; and thevalves should, if possible, be of thelow -capacity type in which the elec-trode connections are not all broughtout through a narrow " pinch."

The International

THE International Set Contesthas taken place in two parts-in

New York and in Chicago. Unfor=tunately, at the moment of going topress the Chicago results have notreached us, but we are very happy insaying that in the New York con-test four prizes have been awarded to

This fine cup has been presented to the Editorof the WIRELESS MAGAZINE by the Americansfor organising the British Elimination Contest.

When

Set Competition

competitors whose sets went throughthe British Elimination Competition.

Among the judges were Dr. AlfredGoldsmith (chairman), Lloyd Jacquet,Lawrence M. Cockaday; C. WarfieldKoefer, David G. Casem, and EdgarK. James (secretary).

In the class for one -valve and two -valve sets, prizes have been awardedto :-

Wm. H. Dorling of 70, FinlayStreet, Fulham, S.W.6, for aset which was described in theJune (1926) issue of the WIRE-LESS MAGAZINE under the title"The Lightweight PortableThree."

NVm. Fricker of Red RiceEstate, nr. Andover, Hants,for a two -valve set comprisinga tuned -anode high -frequencystage and, a dectector.

John Edward Llewellyn of " Elm-Baldock Road, Letch-

worth, He.rts, for. a one -valveset of original design, of whichmany, of the components werehome made.

AndGeorge, P. . Searle of " Bella

Vista," King's Road, Paign-ton, ;Devon, for a three -valvesingle -dial receiver.

You Have Bought A Set(Continued from page 303)

station, if this is transmitting at themoment.

The filament resistances should beadjusted until the valves are glowingat their proper brightness (accordingto whether bright- or dull -emittervalves are used), and the variablecondensers adjusted.

There may be one or more variablecondensers in the set ; the fewerthere are the more simple will tuningbe. If there is only one, it must berotated slowly until the local stationis heard, when it is a simple matterto so adjust it that the station isheard at the greatest possiblestrength. When there are two con-densers they must be rotated simul-taneously, one with either hand,until the greatest strength is ob-tained.

If the station is some distance

307

away it may be necessary to use re-action (supposing the -set to be pro-vided with a reaction adjustment) inorder to obtain the signal strengthdesired. The reaction should beincreased very slowly, and, after alittle movement of the reaction con-trol,. the variable condensers shouldbe re -adjusted, as the effect of alter-ing the reaction coupling is to alterthe tuning of the circuits.

Reaction should be used very cau-tiously at first, as too much reactionivill cause the set to "oscillate," whenit will interfere with the reception ofnear -by listeners. The reaction coup-ling should be loosened a little at thefirst sign of distortion. As long asthe reproduction of the set is per-fectly pure and undistorted, there isno danger of interference beingcaused. G. N.

f-

Wireless Magazine.Abvemben1926

THE INVERSE DUPLEXs

A Special Article by J. F. JOHNSTONTHOSE people who have been

reading wireless periodicals forthe last two or three years cannotfail to have noticed that of the largenumber of reflex circuits publishedonly a very small proportion makeuse of dual amplification in morethan one stage.

For this reason those reflex circuits

Fig. 1.-Ordinary Reflex Circuit.

employing one valve and a crystalare by far the most popular as, forthe results obtained, the saving invalves is half. When more valvesare used in the set without increasingthe number of reflex stages the savingis not so great.

For instance, in a three -valve reflexset comprising only one stage ofdual amplification, a valve detector,and one straight L.F. stage, the re-sults to be expected are theoreticallythe same as those given by a straightfour -valve set with one H.F. stage,detector valve, and two L.F. stages.Actually they will not be quite sogood.

The saving in valves effected inthis case is only a quarter, whichmany will consider not worth theincreased complexity and difficulty ofhandling.

Besides the fact that reflex circuitsincorporating more than one stage ofdual amplification are rather difficultto operate, it is not at all easy tochoose suitable valves for use inthem, which is another reason whysuch circuits are very seldom used.

The choice of valves for use inreflex circuits is always a more im-portant matter than when the circuitsare straight. This will readily beunderstood when it is rememberedthat a valve in a reflex stage iscalled upon to perform two quitedifferent duties.

It is easy enough to obtain valvesespecially suited for H.F. or L.F.amplification, but it is quite a dif-ferent matter to find a valve whichwill do both kinds of work efficiently.

In fact, special H.F. valves andpower valves differ considerably intheir construction. Whereas theformer have small electrodes to keep

the in te r -electrodecapacity 1 o w, t h elatter have large onesto enable a greatamount of energy tobe dealt with satis-factorily.

When only a singleH.F. stage is to beemployed the difficultyis usually solved byemploying a g o o d

general-purpose valve, but this wouldhardly answer in such a circuit as isshown in Fig. i. This is a three -valve circuit which includes fivestages-two of H.F. amplification,two of L.F. amplification, besides thedetector.

The signals produce weak oscilla-tions in the grid circuit of the firstvalve, which are amplifie,d and passedon to the second valve. Thesestronger oscillations are furtheramplified by the second valve andpassed on to the detector for rectifi-cation. The rectifiedsignals will be fairlystrong, owing to thetwo H.F. stages, andthese are returned tothe first valve foramplification at lowfrequency.

After passingthrough this v a 1 v eagain they are ampli-fied yet once more(still at L.F., of course) by thesecond valve before reaching thephones or loud -speaker, which areconnected in the plate circuit of thisvalve.

Now to choose suitable valves forthe reflex stages : One of the general-purpose type will, no doubt, be satis-factory in the first position as here;in addition to the unamplified H.F.oscillations, there are only the

308

rectified impulses straight from thedetector to be dealt with.

But a difficulty at once arises whenwe come to select a valve for thesecond position. Not only are theH.F. oscillations of considerablemagnitude at this point, but the L.F.impulses are also very strong. - Thesignals which are reaching the gridof the valve for the first time havealready been amplified once, whilethose which have passed through thedetector have been amplified no lessthan three times.

Assuming that the original signalswere of fair strength, no general-purpose valve could be expected tofill the second position without beinggreatly overloaded. This is the lastthing we want, meaning, as it does,horrible distortion. What are we todo then? Use a power valve in thesecond stage?

This would mean sacrificing theH.F. efficiency of this stage, and itwould obviously be better to omit theH.F. portion of this particular stageand revert to a three -valve circuiwith only one reflex stage.

The inverse -duplex circuit is de-signed to solve the problem. Itchanges the order in which thesignals pass through the variousvalves, and makes it possible to usegeneral-purpose valves in both reflex

HT+

HT-

LT-

LT4

Fig. 2.-Inverse-duplex Circuit corresponding to Fig 1.

stages without overloading either ofthem. The inverse -duplex circuitcorresponding to the circuit given inFig. i is shown by Fig. 2.

It is very interesting to comparethese two circuits. Up to a pointthey function in the same manner.In both the oscillations due to thereceived signals are applied to thegrid of the first valve, amplified bythis, passed on to the second valve,

again amplified, and then handed onto the detector.

But in the first circuit the rectifiedimpulses are now handed back to thefirst grid circuit. In the inverseduplex they are not. They arepassed back to the second valveinstead. And after being amplified atL.F. by the second valve they are sentback further still to the grid circuitof the first valve for the final stageof amplification. So that In thiscircuit the phones or loud -speakerare connected inthe plate circuitof the first valve.

Now let us seehow the inverse -du ple x circuithelps us in thechoice of suitablevalves. The firstvalve of the set,as we have justseen, has to carryout the secondStage of L.F.amplification, butin addition to thefairly powerfulL.F. impulses ap-plied to its gridit has to amplifyas Well only veryfeeble H.F. os-cillations - t h eunamplified o s -cillations due tothe received sig-nals. It is thusworked veryslightly harderthan t h e firstvalve in the Fig.I circuit.

The secondvalve of the in-verse -duplex cir-cuit has strongerH.F. oscillationsapplied to it thanhas the firstvalve, but t h eL.F. impulses are not so strong.The H.F. impulses reaching the'second valve have been amplifiedonce, but the L.F. signals comestraight from the plate circuit of thedetector valve. So that the secondvalve of the inverse duplex is not sohard worked as is the correspondingvalve of the ordinary reflex circuit.

In the first circuit the first valvehas an easy time while the secondone is badly overloaded. In the in-verse duplex both valves are worked

[ WirelessMagazine.Novemet: 1926

to approximately the same extent-the fiTSI dealing with weak H.F. andstrong L.F. signals and the secondwith strong H.F. and weak L.F.impulses.

This more even distribution of theload on the two amplifying valvesmakes it possible to use general-pur-pose valves in these positions withoutoverloading either 'of theth. The soleobject of the. inverse -duplex arrange-ment is to enable valves suitable forreflex Work to be used in the amplify-

Ugly AerialsHAVE you taken any particular

'notice of the aerials in thecountry districts you have visitedduring your holiday rambles thisyear?

If so, I daresay you will agree withme when I say 'that an aerial whoseirregular lines makes it an eyesore

in a town orsuburb, may look

JUST THE SET FOR THE CHILDREN

Why not make something like this for a kiddie you know?

ing stages without any risk of theirbeing worked beyond their normalcapacity.

FRom 2L0 a whaler has been de-scribing some of his catches. Membersof local angling societies are still bear-ing up under the shock.

TIIE. Italian stations now broadcasta daily news bulletin ;' so-called, webelieve, because it usually mentionssome attempt to put a bomb orbulletin Signor Mussolini.

309

almost a thing ofbeauty in acountry setting.

Much has beenwritten of theugliness of towna n d suburbanaerials, but itseems to methat the uglinesso f n unsym-metrical aerialerected in a rowo f symmetricalaerials is like theugliness of a manin a crowd. Takeyour. ugly manout of a crowdand place him inpleasant s u r -roundings, a n dwherein lies hisugliness?

Does not theugliness of acrudely - erectedaerial lie as muchin the mono-tonous regularityof the symmetri-cal as in the irre-gularity of theasymmetrical?

George says I

have had to lookup three wordsin the dictionary

for that last paragraph. He is quitewrong. I only had to look for two.I guessed the last one.

I have seen some delightfully crudeyet picturesque aerials during myrecent rambles in a country districtwell known to holiday-makers.

Most of the listeners in this districthave adopted the plan of using, asan aerial mast, a rough pole securedto a tree, the bottom of the pole "beingfitted in the tree some feet aboveground level. AERIAL.

[ Wireless Magazine. November, 1926

'Thal b Audition!A special article written byJ. GODCHAUX ABRAHAMS

66DON 'T, for the love of Mike !"gasped the engineer on duty.

Now, to my mind, this remark wasunnecessarily rude, for all I had sug-gested was that I should sing to theB.B.C.'s vast unseen audience; itcould only be excused by a technician'sdoting affection for his pet micro-phone. He had never heard my ren-dering of Vesti la Giubba; had hedone so, possibly his remark mighthave been couched in even less com-plimentary terms !

"Very well," I reluctantly observed," then must I hear others? "

At Savoy. Hill.And so 4t came about that I was

present at an audition given at SavoyHill to would-be broadcast artists.

On this afternoon it was beingtaken in studio No. 2, on one side ofwhich is the echo room, and on an-other, a partitioned -off portion which,for the time being, was filled withsound -producing contrivances of everydescription. Leading out of thisstudio was a small amplification andcontrol chamber to which the judgecould go from time to time to hearhow an artist would come over theether.

The accompanist sat herself at thepiano, the judge at a small table onwhich he had placed his list of ap-plicants, and I, near him, in an arm-chair, drawn up in a corner of theroom from which I could take in thewhole scene.

OpportunitiesIt is to the credit of the B.B.C. that

every opportunity is given to eitherprofessionals or amateurs to displaytheir talents before the microphone;until quite recently, it has been afixed rule that an audition shall begranted to every applicant.

It may interest you to know thatas many as three hundred would-bebroadcasters have been heard in one

week, and it may equally surpriseyou to learn that notwithstandingthis fact, only a small number ofsingers and others could be chosen.

I am told that in a rash momentthe B.B.0 intimated that it sufferedfrom a dearth of broadcast artists ;during the week following this an-nouncement 1,000 applications weresent in from the United Kingdom,and auditions were granted to each inturn. Of this large number, barelythree per cent. were found to be ofvalue to the company.

In order, therefore, to lighten thework of the judges, it has now beenfound necessary to require from eachapplicant a letter of recommendationor certificate emanating from a musicor dramatic academy or private" coach " to the effect that the can-didate is worthy of a hearing. Inthis manner a preliminary sittingtakes place, thus avoiding the grant-ing of an audition to a hopelesslyincompetent performer.

Rare Broadcast TalentIt is not that the B.B.C. has set

itself such a high standard of qualitythat the average artist cannot be in-cluded in the programme, but for thesimple reason that of the many indi-viduals who present themselves forthe test, but few possess the neces-sary attributions for successful broad-cast,. albeit the daily programme in-cludes a variety of entertainments.

You must bear in mind that theconsumption of artists for broadcastpurposes is an abnormally heavy one,inasmuch as at the London and Dav-entry stations alone transmissionsare to all intents and purposes con-tinuous from t t a.m. until I t p.m.and even later nightly.

Moreover; there is a limit to anartist's repertoire, which prevents hisor her appearance at the studio attoo -frequent intervals; in the case ofthe stage, the matter is different, for

310

the daily audience being a small onc,the same play or entertainment mayrun for a large number of consecutiveperformances.

Fictitious NamesAlthough for illustrative purposes I

have given names to some of theartists, I want it to be perfectlyunderstood that these are entirelyfictitious.

"Miss Flossie Bryan," announcedthe call boy. Entered a lady of majes-tic proportions, flanked by two gen-tlemen whose very appearance spelt" agency."

" I am all of a fluster," she ex-claimed. " Do I sing to that box? 'Being assured that the " meat safe "was the microphone, she discardedsome of her outer garments andsettled down to work. Hers was acaster song, of the true third-ratemusic -hall type, with asides and arunning accompaniment of interjec-tions contributed by a male friendwho, presumably, provided the neces-sary atmosphere.

The voice was one which you willhave heard burlesqued in many arevue. The dialogue, to say the leastof it, was vulgar, and although sucha turn, no doubt, would have arousedconsiderable enthusiasm in a garrisonor seaport town, it was evident fromthe first verse onwards that it was inno way suited to broadcast trans-missions.

Courteous JudgeI looked at the judge ; his face re.

tained a look of stolid indifference, butin the words of Harry Fragson " hethanked her most politely," enquiredregarding her stay in town, and withconsiderable courtesy showed her outof the studio.

Exit Flossie. Enter a dramaticsoprano.

In this case, the lady stated thatshe would sing in Italian, a fact

which I endeavoured to rememberduring her performance, as althoughacquainted with the language, not asingle word could I understand. Hervoice was unpleasantly shrill, her highnotes recalling to my mind an oscil-lator's crowning attempt to disturbthe ether.

Interrupted !The last bars of the melody were

brusquely interrupted by the judge's" Thank you ever so much " and Isettled down to listen to further ap-plicants.

" Mr. Lancelot Rembrandt,"monotonously drawled the call -boy.As the newcomer struck a stage atti-tude, so I felt instinctively that hischoice had fallen on "Devil -May -Care," "Gunga Din," or "The Green'Eye of the Little Yellow God " and Iwas right. He mouthed his words,chewed them, gargled them andwould have shouted himself to An in-articulate hoarseness,but for the fact thatthe judge's interrup-tion jerked him to astandstill

" Self - taught," I

murmured. My corn-panion smiled. " Wedo not often get themquite so bad as that,"he observed. " Hemust have given you aparticularly nasty jolt."

Followed a youngpianist, who in thecourse of a few minuteshad treated us to a verybrilliant display ofmusical fireworksParts of his perform-ance, similar to thecurate's egg, weregood, but as a whole.itwas far below the stan-dard acceptable to the

iNiiirelessMagazine,Abvemben1926

stage felt more at home in thestudio.

Theatres DifferIt might be thought that for the

purposes of broadcasting both thelegitimate and music -hall stagescould be freely drawn upon to supplythe requisite material, but without go-ing into the question of contractswhich debar performers from appear-ing before the microphone it must herebe stated that what might constitutea good entertainment in a theatre willfail to please the wireless listener.This, therefore, restricts the field fromwhich the studio can draw its artists.

It is seldom that a star is discov-ered, but you must not think that itis essential to own a powerful voiceto be a successful broadcaster. As amatter of fact, some of the singerswho have become popular with theunseen audience do not possess voicesof sufficient volume to appeal to a con-

cert -hall public, hut theyhave in their notes acertain richness andpurity of tone whichmakes them peculiarlysuitable for radio trans-missions.

The vocalist who isinclined to force his pro-duction in order tomake his voice carryconsiderably mars itspurity, and were hecapable of listening tohis own song would besurprised to find howbadly it is reproduced bywireless receivers.

During the audition Iattended it struck meas an outstanding fea-ture that, in most in -

Auditions are no longer given indiscriminately to dl who ask far them and scenes stances, the words oflike the above (which shows a B.B.C: official testing broadcasting aspirants)

do not place nowarla0. .

the songs _were inatidi-.

ble ; vet, where' theaverage British broadcast listener.

However, when requested to playsomething of a more sober char-acter, his style considerably imprOvedand I gathered from the judge thathe had classed him amongst the" possibles."

The next in turn was a young girlof some eighteen years of age. Herchoice of a song was an unfortunateone; it was far beyond her -.capabili-ties, added to which a bad attack ofnerves robbed her of all .voice control.

Over and above the somewhat un-comfortable feeling usually inherentto the passing of any examination, the

would-be broadcasters had no causefor nervousness. They were not per-forming before a large audience, as,counting the accompanist and thesinger, the studio contained fourpeople only.

I feel that every encouragement isgiven to the applicant. When be-ginners suffer from stage fright every-thing is done to put them at theirease. They are encouraged to choosethe songs which suit them best, andthe professional accompanist at thepiano does much towards giving thema helping hand.

But why will young and inexperi-enced singers invariably choose eitherexcerpts from oratorios or showysong's, from operatic scores whichdemand long and careful study?

By so doing they must, of a cer-tainty, spoil their chances of an en-gagement.

As many as thirty-nine " artists "were heard in the course of some two

hour's, most of them, unfortunately,being Classified as unsuitable "-hopeless, in many, instances, wouldhave been. a, better word.

Where it was evident that the sing-ing of a melody, or the execution of apianoforte composition had beenmarred by the bashfulness of the ap-plicant,_.and where, in the judge'sopinion, ,there were possibilities inthe artist's performance, a requestwas made. for -a 'song or piece of adifferent character,' in their option-" some small thing you like." Inmost cases the second test went infavour of the applicant, who at that

311

,

listener does not see the artist, it isessential that _every word shoUldbe heard. Outside most of. the.studios and. in the rehearsal roomswill be found posters emphasising thefact that the words of a sling are allimportant, and that the artist shouldconcentrate his efforts on good de-livery and enunciation.

As already explained, the auditionis not limited to a mere hearing ofthe performer in the studio but, tomake the test an efficient one, thevoice is actually picked up by themicrophone and conveyed to anotherroom ; in other words, the test itself,

Wireless Magazine. November, 1926

Trial by Audition ! (Continued)

by the judge, constitutes a sample oftheactual transmission heard later bythe outside audience.

Whetting the AppetiteIt may be that on some occasions

you. have listened to the relay of amusical play from the theatre, andthat, a few nights later, your ap-petite, having been whetted by the_samples broadcast, you have in per-son visited that house of entertain-ment.

Has it ever struck you that bymeans of your phones or loud -speakeryou were able to hear spoken wordsmore distinctly than from your seatin the theatre? It has been a frequentexperience of mine, and I attributethe superiority of the relay to thefact that the microphone is placedbetween the stage and the orchestra.

Vocal DefectsIn the case of the broadcast per-

formance,, the orchestra remains inthe background. When you are at thetheatre you hear the singer throughthe orchestra. It is due to this factthat slight defects in the voice are notso apparent in a musical play as whenthe artist sings to the microphone.This receiving instrument is of highsensitivity, and can be as uncharitableto a performer as may be, say, the un-touched negative produced by a photo-graphic lens.

High Standard NecessaryFor this reason a high standard of

quality is required for the broadcastperformance; all failings on the partof the artist are uncomfortably mag-nified by the microphone.

On the other hand this instrumentis fortunately insensitive to everythingbut sound, and this quality has proveda godsend to the many talented enter-tainers who, through physical handi-caps or other disabilities, could nothope to command success on thestage or concert platform.

Talent CountsTalent alone counts, and the studio

is frequently visited by such artistswho have to -day become endeared tothe listening public, and to whom acherished vocation has been vouch-safed by radio.

When, at an audition, some ap-plicants have been judged to attainthe necessary standard, or even, if

classed as " possibles " a furtherchance is given to them to, make good,by their inclusion, at an early date, inthe morning Daventry programme.

Such a performance, as a rule,gives them more confidence to facethe ordeal of the microphone at alater period.

"Not a bad afternoon's work," saidthe judge, as he rose and collectedhis list with the pencilled remarks.

" Four certainties and eight. pos-sibles."

" Is that good? " I enquired." Very satisfactory ! Why, a few

weeks ago I interviewed forty-eightpeople, and not one was of any :useto us."

" Yes," he added thoughtfully," quite a good afternoon's work."

I have decided to spare the feelingsof the British public; I shall notbroadcast!

J. GODCHAUX ABRAHAMS.

ts."1".."1"."-4-.1"..1/-"1,.."1,-.1.esned`'NeA1.#-..VMPMe."\e"."1#-"1.,"""1,4""Nr~v*VMP"Nri"\e'''.1

SPECIAL ALBERT HALL

BROADCAST CONCERTS

THE B.B.C. recently offered animportant opportunity to paling

and lesser known composers ofBritish birth when it proposed agreat musical festival at which ori-ginal musical compositions, for whichprizes amounting to L:5,000 will be

""te,""%e""1"0"\e^%."%e"'NeANeo"..0"1,0"\e"

LET US HELP WHEN YOU

ARE IN DIFFICULTY

Even the most experienced amateur

at one time or another comes up

against some little difficulty-somelittle problem of which the solution

momentarily e'capes him. Haveyou any such problem ? No matterhow trifling or how important the

point is we are always ready to helpyou out of your trouble-we keep aspecial staff just for that purpose.

Moreover, we make no charge

whatever-we are glad to do it IJust write your query on one side ofa sheet of paper (this small pointgreatly facilitates the handling ofyour question) and send it, together

with the coupon on page iii of thecover and a stamped envelope

addressed to yourself for return, in

an envelope addressed to The Editor,WIRELESS MAGAZINE, La Belle

Sauvage, E.C.4.

312

awarded, will be performed. Thusthe young British composer could nolonger be said to suffer from lack ofopportunity for gaining a first publichearing.

It has now been decided that thisfestival shall form part of the planfor holding twelve concerts at theAlbert Hall, which are to be simul-taneously broadcast from all stationsof the B.B.C.

Distinguished conductors havebeen engaged for these performances,which will include not only the prize-winning attempts in the B.B.C. com-petition, but other works of inter-national fame.

Among the conductors are SirHamilton Harty, Albert Coates,Richard Strauss, Sir Edward Elgar,and Otto Klemperer.

Ten More ConcertsThe first two concerts took place

on September 3oth and October 21st,and the remaining ten in the serieswill be performed on November 9th,November 25th and December 56th,5926, and January zoth, February3rd and 57th, March 3rd, 57th, and3ist, and April 54th, 1927.

This is perhaps the most importanteffort yet made to bring good musicinto the homes of the people, and atthe same time of providing the publicwith an opportunity of hearing theconcerts actually performed in theAlbert Hall. B. B. C.

Wireless Magazine. Noventhen 1926

"Let Your Friends Listen!"it" -"Ye

WE have to thank a well-knownmember of the electrical in-dustry-Mr. Borlase,Matthews

-for an idea that we hope and be-lieve will commend itself to wirelesspeople throughout the country.

It is that the period from No-vember 7 to 13 inclusive should be re-garded as National Wireless Week.

B.B.C.'s BirthdayHappily, this period coincides with

the B.B.C.'s birthday, and alreadythere are indications that the pro-grammes to be broadcast during thatweek will have something of thebirthday -party feeling about them.

The idea is distinctly good.Although it cannot be denied thatwireless as a social factor has mademore rapid strides than any othermovement in the history of man,.there are yet-difficult as it may befor WIRELESS MAGAZINE readers torealise-hundreds and thousands ofpeople who never listen -in and towhom wireless remains a completemystery.

One of the objects of NationalWireless Week is that the keenlistener should do missionary workand see that people who up to thepresent have taken no interest what-ever in the subject are invited to hearsome of the very excellent pro-grammes which will ,be put outduring that period, in the hope thatin due course they will have their ownsets and become in their turn devotedand keen followers of the art.

Remember the SloganThe slogan for the week is, " Let

Your Friends Listen," an expressionthat should be taken to heart by every-body who has a set-and neighbours.The ideal is for every keen wirelessman to make up his mind that he willmake at least one convert during thatweek.

The B.B.C. has thrown itself intothe movement with vigour. It hasgone to the expense of providing somevery fine programmes. The trade-the manufacturers' and the retailers-are getting enthusiastic, and all thatremains is for the listener to do hisbest to make the week a success.

It is expected that local dealers willmake special window displays andthat, wherever possible, wirelesssocieties will arrange special meetingsand possibly organise wireless dancesand parties.

Of course, everything hinges uponthe programmes to be broadcast, and,speaking exclusively of, the 2L0 pro-grammes, we can say that they willbe at least notable.

On Sunday, November 7, CarolineHatchard will be singing in theMessiah in the afternoon, and in theevening there will be a Star BalladConcert, in which Elizabeth Schu-mann,. Pouishnoff and other cele-brated artists will take part.

On the evening of Monday, No -

DO YOU WANTTO BUY A SET ?Tell us how much, roughly, youwish to spend; where you aresituated; what stations you wishto receive ; whether you intendto use phones or a loudspeaker,and we will.advise you as to thegeneral lines of sets that willanswer your purpose.

Send your inquiry with coupon(p. iii cover) and stampedaddressed envelope to-

" Buyers' Advice Bureau,"WIRELESS MAGAZINE,

La Belle Sauvage, E.C.4.

313

v ember 8, massed bands will play,and there will be a star variety con-cert, in which Milton Hayes will takepart. On Tuesday there will bea National Concert, and on Wednes-day the Chenil Chamber Orchestra,will play in the afternoon, the Picca-dilly Follies will entertain between6 p.m. and 7 p.m., and there will bea musical comedy, The Little Michu,probably with George. Graves, in theevening.

Armistice DayThursday, November it, is Armis-

tice Day. In the morning the CanterburyCathedral service will be broad-cast, in the afternoon the WestminsterAbbey Evensong from 3 p.m. to3.45 p.m., and in the evening therewill be a special " In Memoriam "programme.

On Friday, November 12, there willbe a Ballad Concert in the late after-noon and a play, The Yellow Jacket,will be performed from 7.30 p.m.. to8.55 p.m. Late in the evening therewill be a performance of I Pagliacci,in which Miriam Licette, FrankMullings,. Harold Williams, andDennis Noble will sing.

Last DayOn the last day, Saturday, No-

vember 13, there will be a perform-ance by the Wireless Military Band.and the London Radio Dance Band.A revue will be given froth 7.30 p.m.to 8.30 p.m., followed by a specialbirthday programme and song re-cital.

This will be a wonderful week inwhich to interest and welcome new-comers to wireless, and the morelisteners we have the better for every-body.

Let us hope that every keen listenerwill do his best to promote the successof the National Wifeless Week." Let Your Friends Listen ! "

Wireless Magazine,Abvemberi 1926

qk

- -03--404-4F-±,-41)----"gt

44, .60. c.C1110

Novelties and New Apparatus Testedand Approved by Our Technical Staff q)

This sketch illustrates the Ormondstraight -line -frequency condenser fittedwith their well-known slow-motiondevice.

The fixed plates are held in twoplaces and are insulated from themoving plates and the frame byfour point -contact ebonite insulators,the total amount of insulating ma-terial used being extremely small.

The moving plates are electricallyconnected to the frame and also to

a circular aluminium shield which is fitted behind the knoband dial to eliminate hand -capacity effects. Both finishand construction are well above the average.

The Ormond Engineering Co., .of 199, Pertionvilie Road,King's Cross, N., are the manufacturers.

Where an extrastage of low -frequency ampli-fication in anexisting receiver C

is desired with-out the necessityof altering thewiring or thepanel layout, theunit illustratedmay be used andwill give excellentresults.

It is known asthe Penton Xtra-

tone Plus Valve Unitand it consists 'of twovalve holders mountedon top of a cylindricalebonite case containinga resistance - capacitycoupling system.

A very efficient balanc-ing condenser is shownin the accompanying

, sketch. The variationin capacity is obtainedby a large coarse -threadedscrew working in betweena helix of brass wire woundin a separate groove.

The minimum capacity isvery small and the maximumis sufficient to neutralise any valve.

The makers are L. McMichael, Ltd., ofHouse, Norfolk Street, Strand, W.C.2.

oar'

The whole isplugged into thelast valve holder-

' of the receiverfrom which thevalve has beenremoved and isinserted With anextra valve in theunit. .

The unit, ismade by ThePenton Engi-neering Co., of13, Cromer St.,

For real poweramplification we canrecommend the newBurndept valve, typeLL 525.

In external appear-ance the valve is alarger replica of theL 525,. but is able todeal with greater gridvoltage variations. Itpossesses a low im-pedance and takes afilament current of .23 ampere at 5 volts.

The makers are Burndept Wireless,Ltd., of A ldine House, Bedford Street,Strand, W.C.2.

11

A grid leak which has a novel meansof varying the resistance is illustratedin the accompanying sketch.

The length of the resistance pathbetween the two metal contact caps is

varied by means of a wire bent in aspecial manner, dipping into a viscousliquid. By rotating the leak, whichmust be mounted horizontally, thelength of wire immersed in the liquidis varied.

The component iscalled the Nonoise grid

In the space at .our disposal it is possible togive only very brief particulars of the com-ponents illustrated. For fuller details readersare recommended to write to the manufacturersconcerned ; in all cases the appropriate ad-dresses are given. Mention of the W IRELESSMAGAZINE will ensure a prompt reply.

Hastings

Made of porcelain, this aerial earthing isextremely efficient in that the receiver is com-pletely isolated from the aerial and earthwhen the plug (to which the aerial and

earth terminals of the receiver areconnected) is removed.

The Athol Engineering Co., Ltd.,of Cornet Street, Higher Broughton,llanchester, are the manufacturers.

leak, and is obtainablefrom the A merican

Radio Corporation, ofi8, Conduit Street;W.1.

In constructing a re-ceiver it is always ad-visable to remember thatat some future time achange of valves may bedesired, and in some

cases this may mean a change of filamentrheostats for the usual high maximumresistance rheostat will not carry thefilament current of many valves on themarket.

A solution to this problem is to use thedual type of rheostat, having two separateresistance windings. Such a rheostat isthe Ormond, illustrated here.

The two resistanceare connected in seriestotal resistance of over

The makers are the Or-mond Engi-neering Co.,Ltd., of 199,PentonvilleRd., N. DULL BRiGHT

windingsgiving a3o ohms.

0 AL.

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60

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314

[ Wireless Magazine. Novrmber 1_926

a nu a e7-Lto-ValVer

A SET FOR THE SHORT WAVES

"Miniwave" is a special term used by theWIRELESS MAGAZINE to designate those wave-lengths below 250 metres, and this MiniwaveTwo-valver is a set built by our Technical

Staff specially for short-wave reception.On test the Miniwave Two -valuer has receivedKDKA, WQO, WIR, and 2XAF, Americanshort-wave stations, on a 30 indoor aerial

in London

WINTER is almost upon us-that season of the year when

the amateur has a better chance thanat any other time to receive, overimmense distances, stations thattransmit on very short wavelengthsand that use comparatively smallpower.

Special ProblemsIn the design of a good short-wave

receiver the problems which confrontus are very different from those en-countered when dealing with thehigher wavelengths.

In the first place, high -frequencyamplification appears to be uselesson the short wavelengths. Thus wehave to rely solely on the efficiencyof our tuning system and detectorvalve. Even the tuning systemscommonly used for ordinary broad-cast reception must undergo a drasticrevision.

The use of a reaction coil of theadjustable type, for instance, pro-duces such a considerable change inwavelength that reception cannot becarried out with any degree ofcertainty.

On the other hand, pure capacity -reaction results in the introductionof stray capacities rendering tuningdifficult.

For the best results the circuitshould be such that the oscillatingpoint is practically constant over theentire tuning range, and it is essen-tial that the change from the stable

Putting finishing touches

to the Miniwave Twa-

valuer before testing

it for " W.M.readers.

to the oscillating condition is gradualand' not sudden.

Bearing these , points in mind,. letus" study the circuit diagram of theshort-wave receiver described in .thearticle.

-

To avoid very critical tuning smallcoils are used so that the wavelengthband covered is not too large. If itis desired to cover other wavelength

Details ofCabinet.

bands more coils will be required,and these can be plugged into thesockets as shown in the photographsand diagrams.

Although the wavelength range ofthe coils is small, the frequency rangeis large, and it is imperative that,for tuning the grid coil of the detec-tor valve, a variable condenser of theslow-motion type is used so that

315

stations separated by a fraction of. a kilocycle may be tuned -in.

A smooth control of reaction isobtained by a. combined magnetic andcapacity coupling, the magneticcoupling being fixed .and the capacitycoupling being variable.

In order to confine the H.F. oscil-lation to the detector valve an im-pedance, in the form of a high re-sistance, is placed in series with thereaction coil and the L.F. trans-former primary ; this effectivelyprevents the H.F. currents from pass-ing through the H.T. battery and soback to the valve.

At the same time, however, theresistance allows tine potential of theH.T. battery to be applied to theplate- of the valve.

The low -frequency valve has theconventional connections and one ofthe new.R.I. multi -ratio transforniersis employed so that the best resultscan be obtained by experimentingwith the seven different ratios andimpedances available.

Maximum SensitivityA grid condenser of small capacity

and a grid leak of comparatively highresistance ensure maximum sensi-tivity from the detector valve.

Fixed filament resistances havebeen employed, and have been foundquite satisfactory. If it should bedesired, hoWever, a variable rheostatmay be used in conjunction with thedetector valve.

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the

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, red

line

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Wireless Magazine. Novembm 1926

The Miniwave Two-valver (Continued)

The componentsrequired for thisreceiver are asfollows :-

Ebonite panel,12m. by 7in.(Becol or Radion,Trelleborgs.)

.00°25-microformlvariable condenser,slow-motion type.(Ormond S.L.F. orIgranic, Dubilier,G. E.C.)

.0002-microfaradvariable condenser.(Polar or Ormond,G.E.C., Igranic,R.I., Dubilier.)

L.F. transformer.(R.I. Multi -ratio orMarconiphone, Pye,M -L, G.E.C.)

500-300,000 ohmsvariable resistance.(Bretwood.)

Two baseboard -mounting valveholders. (Peto-Scott or Burne-Jones.)

.00005-microfaradgrid condenser, airspaced. (Ormond.)

Variable gridleak. (Nonoise.)

Two fixed fila-ment resistanceswith mountingbases. (MagnumResistors.)

8 engraved ter-minals. (Belling &Lee.)

Dimic coil -mount-ing base.(McMichael.)

Fixed plug-in coilsocket for base-board mounting.(Clackson.)

Ebonite terminalstrips din. byzin. and sin.by zin.

Cabinet. (UnicaCabinet Co.)

Baseboard, lain.

Photograph of the Completed Miniwave Two-valver.

hT-H

Circuit Diagram of the Miniwave Two -valuer.

by 6in. by tin.thick. (Unica Cabinet Co.)

Dial indicator marked " Aerial."(Belling & Lee.)

NOTE :-The particular componentsshown in the photographs and allowed forin the Structograph are in each casementioned first.

As there are only two componentsmounted on the panel, the drilling ofthe latter is very simple. The aerial -tuning condenser has a one -holefixing device and is mounted on theleft of the panel, looking at the front.

The reaction condenser is mountedon the right; six holes are required

for fixing it and the dial. Two moreholes, drilled at the bottom of thepanel, are necessary for attachingthe panel to the baseboard.

The sizes of the holes required andtheir positions on the panel can beseen from the Structograph (whichis two-thirds scale).

The remainder of the componentsare mounted on the baseboard in thepositions shown in the photographsand the Structograph.

It should be noted that the Dimiccoil holder is raised about sin. from

316

the baseboard sothat the Dimiccoil and theclosely - coupledaerial coil areconcentric. Bothcoil holders aremounted so thatthe axes of thecoils are at rightangles to thepanel. Sufficientspace must beallowed for themovement of theplates of theaerial -tuning con-denser.

Both terminalstrips are screwedto the back edgeof the baseboard,the smaller stripcarrying theaerial and earthterminals on theright, and thelarger strip onwhich the batteryand phone ter-minals aremounted, on theleft.

The detector -valve holder andthe grid leak andcondenser a r emounted practi-cally in the centreof the baseboard,and close to-gether, so thatconnections fromthe coil to thedetector v al v ethrough the gridleak and conden-ser are as short

as possible for greatest efficiency.In design the variable grid leak is

very novel and is particularly efficient.A variation in resistance is obtainedby a wire bent in a special manner,and dipping into a viscous liquid con-tained in a glass cartridge -type case.The electrical path is lengthened, andthe resistance is consequently in-creased by rotating the whole in onedirection. A fixed leak can be sub-stituted, as shown in the circuit andwiring diagrams.

For proper working of the variable

LT +

Wireless Magazine. November. /926 1

A Special "W.M." Set for the Short Wavesleak it is essential to mount it hori-zontally, and this can be done con-veniently by mounting the componentin two small clips bolted to the twoset plates of the grid condenser.

Law -frequency TransformerThe low -frequency transformer is

screwed to the baseboard imme-diately behind the reaction condenser.

Wiring should be carefully carriedout in conjunction with the colouredStructograph..

The connections shown in red de-note the filament -lighting circuit,those in black the grid, circuits; theremainder are shown in red andwhite.

Furthermore, every terminal ismarked with a small letter of thealphabet, indicating the order.- inwhich wiring should, be carried. out.All those terminals marked a, for. in-stance, should be connected up firstwith as few and as short connectionsas possible. Then all those marked

b are joined together in a similarfashion, and so on.

Connections to the L.F. trans-former should be made with shortpieces of flex so that experiments maybe' made with regard to the best ratioof transformation. .

The variable resistance need notnecessarily be mounted to the panelor baseboard, but can be held in posi-tion by the NO. 16 -gauge tinned -copper wire that should :be used totwiring.

Suitable ValvesHaving completed the construction

of the set 'the next step is to learnhow to operate it. In the first placesuitable valves must be used. Forthe detector valve we recommend theOsram DE8- H.F. or DEsB, or theMullard PMs for use with a 6 -voltaccumulator. For a 2 -volt acumu-lator the Mullard Mit H.F., theOsram DE2. H.F., or the C,osSor RedTop give good results.

The low -frequency amplifying valvemay consist of an Ostam DE8 L.F.,or DE2 L.F., Mullard PM6 or PM1L.F., or the Cossor Stentor Two.

Tuning CoilsWith regard' to coils, the aerial coil

should consist of eight turns of No.i6- or IR-gauge wire wound on azin. former, and attached to a plug.

The grid and reaction coils consistof the two halves of a Dimic coil,No. SW t, the wavelength range inmetres, with the .00025-microfaradvariable condenser, being approxi-mately 35 to 70 metres. For shorterwavelengths (2o to -so metres) the No.SW2 Dimic coil should be used.

The aerial should consist of asingle wire, the total length of which,including lead-in, should not exceedsoft. for the best results. An indooraerial 2Sft. long will serve excellently.Remember that bad connections aremore detrimental to the recepthin ofshort waves than with long waves.

Photograph showing Arrangement of the Components of the Miniwave Two-valver on the Baseboard.

317

Wireless Magazine November1926

THE MINIWAVE TWO-VALVER (Continued)

3'z

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318

Wireless Magazine, November 1926 I

A Special "Wireless Magazine" Design

Another Photograph showing the Construction of the Miniwave Two-valver.

Tuning is accomplished in the fol-lowing manner : Set both dials andturn the reaction dial (on the right)until the set begins to oscillate. Nowturn the tuning condenser through-out its i8o degrees; the set should beoscillating at every setting - of thisdial.

If some difficulty is experienced inproducing oscillations, separate the

aerial coil from the Dimic coil afraction of an inch.

If points on the tuning dial arefound where oscillation ceases it isprobably due to the fact that theaerial circuit is in resonance with thegrid circuit, and is therefore absorb-ing energy from the latter.

To receive broadcasting it is essen-tial that the set should not be oscillat-

ing, but just short of it. The H.T.voltage on the plate of each valvemust be carefully adjusted until thecorrect values are found.

The sensitivity of the receiver issuch that it has received KDKA,WOO, WIR and 2XAF of Americaon a small indoor aerial about 3oft.in length and a water -pipe earth inLondon. Can you do better?

Short-wave Stations for Which You Should Listen

Wavelengthin metres.

Call Sign. Name of Station. System. Wavelengthin metres.

Call Sign. Name of Station. System.

13 POF Nauen (Germany) Telegraphy 25.3 AGA Berlin (Germany) Telephony

18 POF Nauen , , 30 F8GA Clichy (France) ..

20 PDX Nauen 32.79 WGY Schenectady (N.Y.)

20 JIPP Tokio (Japan)* Telephony 33 JIPP Tokio (Japan)*

21 U2XAD Schenectady (N.Y.) 40.2 AGC Berlin

23 FFW St. Assise (France) Telegraphy - [ - Konigswuskerhausen (Germany)t

25 PCMM The Hague (Holland) C2.7 KDKA East Pittsburg (U.S.A.)

* Relays Tokio broadcast programmes. 7 Relays Berlin broadcast programmes.

319

I Wireless Magazine. Abvember 1926

Tr Human Side of BroadcastingA special article by G. DARE FLECK, Programme Director of KDKA

SowE of our wireless experiences arevery thrilling. Broadcasting has

become a vital human experience andsome of the personal contacts formedthrough this agency are very inter-esting. A series of incidents in con-nection with our broadcasts fromstation KDKA to the Far North com-bine themselves into a story more fas-cinating that many tales of fiction.

About Christmas time, 1924, wewere requested to broadcast a mes-sage concerning the ill-fated NuttingExpedition. This consisted of a smallparty of courageous men whose en-thusiasm for exploration was appar-ently much greater than their work-ing knowledge of Arctic navigation.In an attempt to follow the courseof the early Norsemen to this country,they were lost completely.

The message we were requested togive was directed particularly to theHudson's Bay Posts and CanadianMounted Police in East Baffinland,asking for information regarding bitsof wreckage, or any other clue to thefate of this expedition which might bereceived from the Eskimos along thatcoast. Several times during the earlyweeks of 1925 this message was sentout. Imagine our surprise one daywhen a visitor to the office of KDKAhanded in his card-which read" Rev. Blevin Atkinson, Lake Har-bour, Baffinland."

Great SurpriseWith the word Baffinland already

impressed upon our consciousness asa vast, bleak, uninviting waste, therealisation that here was someonefrom that part of the world came asa great surprise, and was the first ofa series of remarkable coincidences.

The reverend gentleman and hiswife, who accompanied him to ouroffice, are missionaries stationed atBaffinland, but were home on furlough,and at that time visiting relatives ofMrs. Atkinson in Pittsburgh. Theyhad heard of our appeal to Paffin-land for information regarding theNutting Expedition, and came to ouroffice to assure us that stationKDKA is heard throughout thisnorthern country wherever receivingsets are installed, which is in the

occasional post of the Hudson's BayCompany or at the temporary campof the police who may be assignedthere for duty.

The Atkinsons told of their joy athaving heard the service from Cal-vary Episcopal Church, Pittsburgh,

KDKA needs little introduction to

readers of the WIRELESS MAGAZINE-it is sufficient to remind them that thecall sign is that of the WestinghouseElectric Co.'s station at Fa .t Pittsburgh,Pa. We are glad to hcv2 this oppor-tunity of bringing the station's activitiesinto closer touch with British listenersand we are sure that this special articleby G. Dare Fleck, Programme Director,

will be read with great interest

by radio, the only English servicethey had listened to for months, asall services conducted by them wereof necessity in the Eskimo language.The receiving set by which they heardthis service belonged to a memberof the police, but when they returnedthe Atkinsons expected to take withthem a radio set by which they couldmaintain this contact with civilisa-tion.

It was a very interesting call, andwhen the Atkinsons left our office wefelt we had a real interest in thegreat North where they are servingand where we might help to brightensome of their days with our radioprogrammes once they were backagain.

Some time in July, about sixmonths after this visit from theAtkinsons, we were requested to sendanother message to the Hudson's BayPosts in the far north. It was newsof a disaster. The Bayeskimo-,supply ship to these posts, on itsannual trip north, had been crushedin the ice. All supplies had beenlost, though the human freight hadbeen saved and later transferred toanother vessel.

The posts were assured that anothersupply vessel would be equipped atonce, and would be on its way withthe necessary supplies in about threeweeks. These posts were thus

320

assured that winter would not findthem in danger of privation andstarvation. Several evenings thismessage was repeated to make surethat it might be received by thoseinterested.

A week after this message had beenbroadcast a letter came from Canada.It was from the brother of theReverend Blevin Atkinson, thankingus for the message which we hadbroadcast assuring those interestedof the safety of all the persons onboard the unfortunate Bayeskimo.

This letter told us that the ReverendBlevin Atkinson and his wife werereturning to Baffinland on theBayeskimo, and it was a great com-fort to the relatives and friends ofthis couple to know they were safealthough their personal baggage hadbeen lost.

The summer passed and the chilldays of autumn arrived. On the nightof Hallowe'en, in the midst of dancemusic and revelry, another messagewas broadcast to these men abovethe Arctic Circle. It gave the infor-mation that one of the posts had notbeen reached by the supply vessel onaccount of the closing in of the ice.

" Send Supplies ! "It requested other posts in that

region to attempt the transportationof supplies across the ice by meansof dog teams in order that the neededsupplies thight reach those waitingat this lonely post. It was a mes-sage which carried with it a thoughtof distress, privation and possiblestarvation if it failed to reach thn.efor whom it was intended.

Night after night this message wasdriven out across the ether waves,carrying with it the prayer that itmight be successful in its mission.Eight thousand miles away, in SouthAfrica, it was heard so clearly that itwas published in one of the news-papers of Johannesburg, South Africa.

During the latter part of Novem-ber other messages were broadcast tothose members of the Royal Cana-dian Mounted Police and Hudson'sBay Posts beyond the Arctic CircleOn a schedule which had been suppliedthese men when the annual mail wentto them.

Wireless Magazine. Not emben /926

Pleasing NewsWhen the supply boat returned

from its annual trip it brought us thepleasing news that the, radio set takenback to Baffinland by the Atkinsonshad been installed, and in the brieftime before the return of the boathad proved successful in receivingstation KDKA. This encouraged usin the belief that the messages sentduring the winter were reaching thesefar -away listeners.

The last of these scheduled broad-casts was on February 20, whichin those places marked the time when

the sun reappeared after its longabsence, and although no thought ofthis was in our minds when theschedule was made up, we inadver-tently assisted in celebrating thereturn of the sun, an event of greatimportance in the lives of those in thatnorthern region.

Some of the messages were for ourfriends the Atkinsons, two of themcarrying the news that relatives hadpassed into the Great Beyond. Onecontained a touch of comedy. Itcame from a class of Sunday schoolgirls in Canada, and assured the

Atkinsons that an artificial Christmastree was being sent to replace the onelost with the Bayeskimo. Imaginesending an artificial Christmas treeright into the home territory of SantaClaus!

Not the EndOf course, this isn't the end of the

story. We expect to hear from thesefriends again when the supply boatcomes back this year. And on theirnext furlough we trust they will visitus. But isn't it a real human -intereststory?

T-^'V°'4°'1e^'4' Ni.#'1,#*\r^"el

Microphones Do Not Respect Persons !4.A.0"..eiVes\AriVe010.ree.%.."...-010.0.40.90\nroVe"..""AroVsNoriVroVe

AN unusual incident occurred atSt. Martin - in - the - Fields

Church, London, in September, dur-ing the broadcast of a service. Awoman member of the congregationbegan to pray aloud, apparently inan ecstasy of religious fervour. Herprayer was broadcast with the restof the service, to the surprise andbewilderment of listeners.

The microphone isno respecter of per-sons or of words.Dropped h's arepassed on to the lis-tener ; discords a r enot taken out, theyare passed on to theother end.

While talking aboutbroadcasting to a fewof my friends I wastaken aback by theassertion of one whostated that he hadbroadcast from a par-ticular hall in theNorth of England. I

knew he had neverbroadcast, and askedhim to explain.

He was a hecklerat a political meetingaddressed by one ofour leading statesmen during thelast general election. The address ofthe statesman was broadcast, andthe interjections of the hecklers. Heshouted a question across the hall,and as it came when there was apause in the speech of the politician,it had the microphone to itself andreached the listeners.

l'here are many more similar

broadcasters; although they havenever appeared on the programme,their voices have been heard in homesand halls hundreds of miles away.

Recently, a sketch was beingbroadcast from the London studio.The prompter, although he did nottake one of the parts, and althoughhe only whispered, was clearlyaudible, and many of his sentences

The wireless craze has

came

reached as far as Penang, as this photograph shows :note the Brown loud -speaker.

through before they werespoken by the party in the sketch.Announcers' whispers often reach theears of listeners.

When I visited one of the B.B.C.studios for the first time, to broad-cast, my wife was at home eagerlylistening. The moment for my talkhad arrived, the previous item ended.Then she heard a whispering ques-

321

tion, "'How do you pronouncename? " and my answer to it.announcer might have saidthing not meantLuckily he did not.

On another occasion, however, anannouncer did say something thatwould have annoyed many listenershad they heard it. He was on pins,while I was talking, for he did not

know until later thatwhat he had spokenwas not broadcast.

Perhaps the occa-sion when the micro-phone revealed that itwas no respecter ofpersons or of wordswas during a banquetwhen the speecheswere broadcast. Per-sons of great famewere present on thatoccasion - journalists,artists, lawyers, andstatesmen. The prin-cipal guest of t h eevening was Lord-. When he got upto respond to t h etoast, another states-man, whose voice themicrophone did notalter in transmitting

it, said : It's a pity he hasn't asmuch brains as he has hair."

One wonders what the statesmanand the chief guest said of eachother when they found that thesentence was broadcast! E.B.R.

yourThe

some -for listeners.

Are you thinking of buying a set?If so, turn to the "Guide to the BestValve Sets " on p. 346.

rel e ss Magazine, November. 1926 I

Newcomers, but Already Popular-

NAT LEWIN AND HIS NEW VERREY'SDANCE BAND

SLADE

322

Mrs. H. A. L. Fisher writes on-

roadcastducationAnd Its Wondrous

Possibilities

ONLY a very little time ago wire-less, to most of us, was a

mystery, possibly quite exciting, butso remote, so unknown, so unlikelyto come our way or to affect us thatwe gave it but little thought. Andnow, to -day, here it is, part of thefurniture, and a very considerablepart, of every -day life.

Moreover, it comes into the livesnot only of city dwellers, or theman who works with others and is

. part of a great world, but even moreinto the every -day experience ofcountry people and of women whosework keeps them in their homes.

Because, therefore, it touches thosewho have hitherto been but slightlyaffected by social developments, it isperhaps destined to have even moreinfluence than the other marvellousthings that have come upon us of lateyears. But it has come so silently,and so swiftly, as well as so com-pletely, that we have had but littletime as yet to think out its possi-bilities and its implications.

Our Most Pressing ProblemNot the least of these is the rela-

tion of wireless to education. For, aswe are beginning to understand,though not even yet as fully and asfervently as we ought to understand,education, the training of the youngfor the duties and responsibilities ofadult life, above all for citizenship, isthe most urgent, the most pressing,of all the many problems that con-front us.

A wise, well-educated democracyshould be the best and surest of allmethods of government, but an ill-educated, or imperfectly educated,democracy is exposed to very gravedangers.. And as the world becomesmore and more a democratically -

Mrs. II. A. L. Fisher, wife of theex -President of the Board of Edu-

cation, is well known for her interestin educational matters, and in this

article she has new light to throw

on the fascinating subject of broadcast

education.

governed world, so clearly it behovesus all to give our very utmost to theproblem of planning and providingthe best education for the citizens ofthe future.

Now the majority of these citizenswill certainly receive their training inthe public elementary and secondaryschools of the country. It is only thefew, even if an important few, thatare educated elsewhere. So that thefirst question I want to ask aboutwireless and its possible contributionto the problem of education is, whatcan it do for the public elementaryand secondary schools? What has itto offer that they can accept, whatcan it do for the children which is notalready done, and which is worthdoing?

323

Wireless Magazine, Nove,,,ben 1926

Our schools are institutions ofwhich we have every right to be ex-tremely proud. They are not per-fect, as those who work them are thefirst to tell us, but they are, upon thewhole, extremely good, and they arestaffed by teachers who do splendidwork.

But teachers, like mothers (alsopeople who play an important partin education), cannot often bespecialists. They have to teach, par-ticularly in the smaller schools, anumber of different subjects, and theyteach them extremely well. Butwireless can do what the ordinaryschool cannot do, and that is com-mand the services of the specialist.

It is perfectly easy for even a verybusy person to go to a central studio,probably in London, where such aperson is quite likely to be anyhow,and to speak, through wireless, withthe minimum of effort, to children allover. Great Britain.

With the best will in the worldsuch a distinguished person, or indeedany person, can only reach a fewgroups of children in the ordinaryway, but by wireless he or she canreach them all. Therefore here is oneextremely obvious and extremely, im-portant way in which wireless canhelp education,

Expert into Every SchoolIt can bring the expert into' every

school, it can enable every child tohear the voice, to come into somesort of contact with the mind, of the

Wireless Magazine, November 1926

Broadcast Education and Its Wondrous Possibilities (cont.)

best teachers, the most distinguishedexponents, of almost every subject.

All this wants working out. Itstechnique needs much study, not onlyon the part of the distinguished, whomay not be experienced in the art oftalking to school children, but alsoupon that of the ordinary teacher,who has to work out, so to speak, anew aspect of school life, the helpingof the children to get the best resultsfrom listening, not to a presenthuman being, but to a loud -speakerwhich, whatever its merits, certainlylacks personality.

There Is PersonalityYet no one who has listened to

lectures of various kinds with the aidof the loud -speaker can deny that aconsiderable amount of personalitydoes come through, and it may besurmised that the people who conbest hold the children's attention willbe the people who can give person-ality to their broadcasting.

In any case, here is one certainlyundoubted and surely important thingthat wireless can do. For every onewho gives thought to the matterunderstands how extraordinarilyvaluable it is to the developing mindto come into contact with the ripeexperience of greater minds, and hereis a method by which any child, inhowever remote or small a school,can obtain that experience, if not inthe most complete way yet surely inone which is well worth while.

Another advantage that seemsfairly obvious applies more particu-larly to the smaller schools, and thatis the greatly increased variety ofteaching which can be provided bywireless means. Children gaintremendously by, and appreciateenormously, variety in teaching.

A child who has had only one ortwo teachers, however good, misses agreat deal of the stimulus and in-terest obtained by the child in alarger school who learns from anumber of different people.

The teacher in a small countryschool has a very close personal rela-tionship to the children, closerpossibly than that of the teacher in abig school, who only gets them forone subject, or while they are in oneor two classes or years.

But in future, when the possibilitiesof wireless are fully developed, the

teacher in a small school, while pre-serving that close relation, can alsogive to the children a useful and,refreshing change of teachers, 'achange which will probably help notonly the children but the teacher aswell.

In the same way children whothrough illness or for other reasons

N.Po'1,"1"."1"^"V-M.,^1"."1r""\e,"1r^Nos.N.r

Simultaneous Talks

Worth Listening For

MUSIC AND THE ORDINARYLISTENER, by.Sir H. Watford Davies,

Mus. Doc., on Tuesdays, November 2, 9,

16, 23 and 30, at 9.30 p.m.

HISTORICAL SKETCHES, by Col. W.

P. Drury, on Wednesdays, November 3,

10, 17 and 24, at 7.10 p.m.

ATOMS AND WORLDS, by Sir OliverLodge. on Wednesdays, November 3 and

10, at 9.30 p.m.

THE MIND OF ANIMALS, by Prof.J. Arthur Thomson, M.A., LL.D.(Edin.),

on Thursdays, November 4 at 7.10 p.m.,

and November 11 and 18 at 7.40 p.m. cl

SIX GREAT ARTISTS AND WHATTHEY STAND FOR, by Mr. C. Lewis

Hind, on Thursdays, November 11,

18 and 25, at 7.10 p.m.

COMPANIONABLE BOOKS, by Prof.G. Gordon, M.A., on Wednesdays,

November 17 and 24, at 930 p.m.

SPANISH TALKS, by Mr. W. Bletcher,on Tuesdays. November 2, 9, 16 and 30,

at 7.10 p.m.

FRENCH TALKS by M. Stephan onTuesdays, Nov. 9 and 23, at 7.10 p.m.

are taught at home can have lessonsfrom a number of outside teachers,and command a far greater variety ofexperience than is .obtainable by anyether, means.

Here, then, are- two possibilities,which even if there were no more--lnd to my mind there are many-;nust surely mean that educational

324

experts should give their minds to thequestion of wireless and education.Quite certainly it is all still in the ex-perimental stage, with as yet an im-perfect technique probably both inthe schools and at the microphone.

Lecturing to many thousands ofschool children of varying ages is anart which requires a good deal ofthought and care, making sure thatthe children follow the remarks whichfall from the loud -speaker, makingthem fit into the other lessons, mak-ing them a real part' of the child'sexperience and training also needsmuch thought and care.

But it is worth while, for by itsmeans the children's experience canbe immensely widened, the teacher'swork supplemented and helped.

It is also clear that much needs tobe done before the lectures given atthe central studio can be completelyadapted to the needs of children ofvarying ages and attainments. Therelation between the schools andthose who organise school wireless isstill rather vague and sketchy, andit is far from easy to be sure that thekind of teaching provided is thatwhich is most required.

As more and more schools comeinto touch with the broadcastingauthorities, so all this can be workedout in detail, and a greater varietyof lectures arranged.

Older StudentsNor is it only elementary schools

that may profit in this way fromwireless teaching. One can imagineall sorts of possibilities for olderstudents, of secondary -school age, orolder still. It all needs a great dealof thinking about, and a great dealof combination and co-operation.

But that it can be done, should bedone, and is well worth doing, thatby the aid of wireless a very largenumber of children can get teachingfrom men and women who are thegreatest authorities upon or expon-ents of their own subjects, that olderpeople can continue to learn and toenjoy learning, that a greater varietyas well as a greater richness anddepth can be added to the generalmass of educational experience-allthis seems .to me indubitable. Thewhole thing is new, experimental,imperfect, but it is full of possibilityand of hope. LETTICE FISHER.

I-Wireless Magazine.November:1926

barging our alleriesAfZivs

4'4

ALUMINIUMROD 1" DIA.X " LONt,

\----SCREW WHIT

ALUMINIUM ROD4xA"Lor1c x 4:DIA

DIA. MOLES TOHOLD WOOD PEGSFOR CENTERINGROD IN LEAD

Fig. 1.-Fixing the Rods.

ARRANGEMENTS for chargingaccumulators from direct -cur-

rent lightingmains a r esimple, butwhen the sup-ply is alternat-

n g currentsome form ofrectifier mustbe used, be-cause one cancharge onlywith D.C.

The simplestand cheapestform of recti-fier for thepurpose is theNodon valve;though quite satisfactory, it appearsto have fallen somewhat into dis-

favour on account of dif-ferences of opinion as tothe best electrolyte to be usedwith it.

These notes describe howto make a perfectly goodrectifier, the data being thoseused by the writer in makinghis own.

In brief, the apparatus is acombination of cells, eachcontaining two plates, leadand aluminium, immersed inan aqueous solution of am-monium phosphate.

The materials requiredare :-

CIRCULATIOM-PIOUS

LEAD PIPE3" IM.----*

LUGS FORMEDBY CUTTINGAWAY PIPE

Fig. 2.-Cutting Lead Pipe.

and 21n. long. meter rods also4 lengths aluminium rod, tin. dia. Whitworth nuts. Drill the tin. dia-

to take the eightwooden plugswhich are forcentering theserods in thelead pipes.

With a hack-saw cut thelead pipes asshown in Fig.2 so as toleave two lugs

long, andcut circulationholes asshown. Slotand drill thepieces of wood

LLAD-

ALUMINIUM

AMMETER

?A-0 VOLTSA.00

Fig. 4 (left).-Cell Connections.Fig. 5 (above).-Resistances in Mains.

1"

Wool)

_L_ BLOCK

11."

LEVEL OFSOLUTION

ROBBER TUBEtOVERRIG V4"ALUMINIUM ROD

l"DIA. ALUMINIUMROD.

Fig. 3.-Assembly of Cell.

4 lengths aluminium rod, tin. dia.and 4iin. long.

4 LecIanche jars, 3 -pint size(about 4iin. sq. and Shin. high).

4 pieces lead piping, 8in. longand sin. dia.

8 hard -wood pegs, thelength of the internal diameterof the lead piping and tin. dia. AC

4 lengths rubber tube to cover.in. aluminium rods.

4 pieces of hard wood, tin.wide by tin. by 41in. long.With regard to this wood,

accept a word of warning.Do not use ebonite instead, inthe hope of making a betterjob. Ebonite does not suit sowell as wood, for reasons thewriter has not discovered.

Drill and tap the tin. dia-meter rods to take the tin.diameter rods Fig. t). Screwthe other ends for two tin.

to receive theleaden lugs (Fig. 3), bending the lugsover as shown, one being fitted with

325

WOODSUPPORT

ALummunPLATt

LEAD PLATE.

CONTAINER

ALUMINIUMPLATE

Fig. 6.-One Rectifier Cell with Transformer.

Wireless Magazine.Novemben.1926

Charging Your Batteries from A.C. Mains (Continued)

a screw terminal and the other beingused merely as a support.

The electrolyte must be preparedfrom chemically -pure ammoniumphosphate, lb. per pot being dis-solved in enough water to fill 'eachpot to the level indicated in Fig. 3.Ordinary tap water will serve.

Connect up the cells as shown inFig. 4. The accumulator when oncharge can be connected with itsnegative terminal to lead and itspositive to aluminium. An ammetercan usefully be inserted in series witheither terminal of the accumulatorand its corresponding rectifier elee-trode, for observation of the chargingrate.

Now comes the, question of thesupply voltage. A step-down trans-former gives the greatest efficiency,but as a standard transformer for thispurpose cannot be purchased. thewriter uses lamps or other forms ofresistance in the A.C. mains, asshown in Fig. 5.

The lamps at present in use (for thevoltage shown) are four zoo -volt

250 -watt carbon lamps of the sausagetype, as used in glowlamp radiators.The resistance is, of course, varied tosuit the particular accumulator beingcharged.

The rectifier described will operate

.#-AWrftw.eowawvo.1~W.."1,1YOUR QUESTIONS ANSWERED

At some time or other you are certainto come up against some difficulty in

wireless that you cannot solve unaided.Instead of worrying yourself with

knotty problems, let the Technical Staffof the WIRELESS MAGAZINE answer yourquestions for you.

Write your question on one side of apiece of paper, attach to it the coupon oncover iii and send it, with a stampedaddressed reply envelope, to The Editor,WIRELESS MAGAZINE, La Belle Sauvage,E.C.4.

at 2-3 amperes output, and has evenbeen run satisfactorily for severalhours at 5 amperes output, thoughwith too much heating.

A curious point about this heatingeffect was observed which may tempt

readers to hazard experiments andtheories. It was found that if the ac-cumulator was switched off while thepots were very hot it was impossible.to start charging again until 15-*minutes of cooling had elapsed, other-'wise the current was reversed.

If a transformer be preferred toresistances, each half of the secondaryshould deliver about 4n volts (see Mg..6).

Further, when a transformer is:used it is advisable to have only one:double -wave rectifier, of about 3 -pintscapacity (Fig. 6). Although the.transformer method is the more effi-cient it will be found that regulation:of the charge is much more stablewhen four rectifier pots are used with.a resistance in the mains. .

The single -pot rectifier is made up.of one leaden plate and two alumi-nium plates, taken through slots toscrew terminals in a piece of hardwood which rests across the top of thepot. Suitable dimensions for theseplates are 4in. long by zin. wide.

E. BLAKE.

Cs.""'4%,"\e''',..1..-"Vo",,,,,,'"No,"\,""\e"1,0"1""1"."1#"",,"1.,-"At,.'%,",,,-1,^1.".^"1,""\r""\e"1"."1",^' .^1r^1.^'Ar**1,^-1.,"%r^"\r"1,""Sr"SrMe.)

Dr. E. E. Fournier d'A'be Explains-

HOW THE MOON

1 -1 -THAT the changes of the moonhave any perceptible effect upon

the weather is a fallacy which hasbeen exploded long ago. But it is byno means certain that the moon hasno influence upon wireless trans-mission.

Properties Besides LightMoonlight itself, being only one -

millionth of the intensity of sunlight,can have no perceptible effect analo-gous to that of sunlight. But thereare other properties, of -the moonwhich may come into play.

Professor Marcel Brillouiti, of theCollege de France, pointed .this outat a recent meeting of the ParisAcademy of Sciences.

The density of the moon is 3.3times that of water, and is thereforeabout the same as the density of theearth's crust.

AFFECTS TRANSMISSION

There is every reason to supposethat the material of the moon isderived from the earth, and consistsof the same elements.

It must, therefore, contain ura-nium, thorium, and all their progenyof radio -active elements, includingthe " emanations," which are reallygases in a state of radio -active dis-integration.

Now the behaviour of these eman-ations must be affected by the enor-mous changes of temperature under-gone by our satellite month bymonth. The dark side of the moonfalls to the neighbourhood of theabsolute zero of temperature, whichis at some 46o° of frost.

When the sun shines overhead thetemperature must, in the absence ofan atmosphere, rise to somewherenear the boiling point of water. Thedistribution of the radio -active gases

326

must be profoundly influenced bythese changes.

The helium atoms and electronsgiven off by them, as well as thepenetrating radiations, may wellreach the earth's atmosphere in alittle over a second. They will thencontribute to the ionisation of ouratmosphere and the density of theHeaviside layer.

Discoverable EffectThis effect should be quite dis-

coverable by careful systematic ob-servations. Not only would wirelesstransmission be affected by moon-rise, but the earth's magnetism andthe absorption of starlight shouldalso show some effect.

Such observations could then besupplemented by laboratory experi-ments on the light fusible silicates ofwhich the moon probably consists.

Wireless Magazine. November 1926

COSMOPOLITAN NINEA

THREE, -UNIT

SUPER -HET

3-TheLow-

frequencyAmplifying

Unit

Although specially designed for the Cosmopolitan Ninethis unit is suitable for use wherever an amplifier is needed

T N this article we are describing the1 third and last unit which com-pletes the nine -valve super -het whichwe have called the CosmopolitanNine. This unit consists of a two -valve low -frequency amplifier, thefirst stage of which is transformerand the second stage resistance -capacity coupled.

The only control on the panel is afilament rheostat which. adjusts thefilament current of both amplifyingv al v e s. Immedi-ately below this con-trol is a two -pointjack into which

.the loud -speaker isplugged. The fila-ment rheostat formsa convenient volumecontrol.

By using a goodMake of transformerfollowed by a resist-ance -capacity unitthe best . reproduc-tion of speech andmusic is obtained

A resist-ance -coupled valvewill amplify nearlyevery note with a

constant amplification, and it shouldtherefore be seen that a transformeris used which has similar qualities,although there is no transformermade which will give such constantamplification as the resistance'coupling.

The transformer, however, willgive much greater total amplificationthan the resistance method, arid thatis why we have used one stage.

It is essential that a good loud -

speaker is used if the amplifier is tobe given a fair chance. The bestamplifier cannot convert a poor loud-speaker into a good one. This factis overlooked by many who giveevery care to the making of a goodset and spoil it by buying an inferiorJouckspeaker.

Returning to the amplifying unit,let us study the circuit diagram. Itwill be seen that the two input ter-minals are connected to the primary

terminals of the trans-former, and, whenwiring up the unit, itshould be seen thatthe plate of the detec-tor valve in the secondunit is connected tothe terminal of thetransformer marked" plate " in this unit.

The secondary ter-minals of the trans-former are connectedto the grid of the firstamplifying valve andto a common nega-tive grid -bias tapping.

In the plate circuitof the first valve thewire - wound resist-

Circuit Diagram of the Amplifier Unit.

327

I.

Wireless Magazine. November 1926 j

The Cosmopolitan Nine (continued)

Photograph showing rillsiSaltiltitn Compchgents in the

ance is inserted, and the couplingcondenser between the plate ofthis valve and the grid of thelast valve prevents a high posi-tive potential being applied to thegrid while, at the same time, itallows the passage of low -frequencyoscillations.

Low Capacity BestThe size of this condenser is not

and it .is good practice tokeep the capacity at as low a valueas is consistent with good results.We have used one -having a capacityof .05 microfarad.

Two H.T. + tappings are provided,enabling the correct voltage beingapplied to the plate of each valve.Each H.T. + tapping and H.T.-- isshunted with a 2-microfarad fixedcondenser.

The grid leak, connected to the gridof the last valve, should have a lower

Amplifier Unit of the Cosmopolitan Nine.res;iy!lye than is usual with H.F.work. "To some extent the valuedepends on the capacity of thecoupling condenser, but the actualvalue is not very critical, and a leakhaving a resistance of .25 megohm(25o,000 ohms) will be found satis-factory.

All the components needed for theamplifier are given in the followinglist :-

Ebonite panel, gin. by yin. (Radion orBecol).

Baseboard; gin.. by by 5in., andcabinet (Unica Cabinet Co:).

3o -ohm filament rheostat (Lissen orOrmond, G.E.C., Penton, R.I., etc.).

L.F. transformer (Ferranti A.F.3 orMarconiphone).

2 baseboard -mounting valve holders(Magnum or Benjamin, Lotus).

6o,000 -ohm wire -wound anode resist-ance (Varley or Dubilier, Mullard).

.25-megohm grid leak (Dubilier orMullard, Ediswan).

2 2-microfarad fixed condensers(Dubilier or T.C.C.).

328

.05 - microfarad fixed condenser(Dubilier or T.C.C.).

2 -point jack and plug (Bowyer -Loweor Igranic).

.00t -microfarad fixed condenser(Wates or Mullard, Dubilier).

9 engraved terminals (Belling andLee).

Ebonite terminal strip, gin. by tin.NOTE.-The particular components

shown in tke photographs and allowedfor in the dimensioned layout are ineach case mentioned first.Four holes only are to be drilled

through the panel, one for the fila-tnent rheostat, one for the jack andtwo for fixing the panel to the base-board. The dimensions of the holesand their positions are clearly in-dicated in the wiring diagram.

On the BaseboardOn the baseboard .the transformer

is mounted on the right (looking atthe back) and the two 2-microfaradfixed condensers on the left. The

Wireless Magazine. November 1926

A Special "Wireless Magazine" Design

Another Photograph showing

two valve holders are mounteddirectly in front of the transformerand fixed condensers and close to theback edge of the baseboard, whilethe anode resistance, coupling con-denser and grid leak are seen betweenthese components, in the centre ofthe baseboard.

Along the back edge of the base-board the terminal strip is mounted,carrying the nine terminals. Read-ing from left to right these terminalsare as follows :-H.T. i (supplyingthe last valve), H.T. +2, H.T.- ,L.T. -F, L.T.- , grid bias -, gridbias +, input +, input -.

Wiring is quite simple, and shouldbe tackled in conjunction with thewiring diagram. This diagram issufficient in itself, and any explana-tion as to how the wiring is carriedout is superfluous.

The grid leak should be fitted into

the arrangement of the Amplifier Unit of the Cosmopolitan Nine.

two metal clipsand the con-necting wiresshould be sol-dered to them.

If thick -gauge wire isused for con-necting p tt r -poses there isno need to fixthe grid leakeither to thepanel or base-board.

T h e wiringitself is suffi-cient to hold itin place.

In any casethe connectingwires must onno account be

Completed Amplifier Unit.

329

Wireless Magazine, hbvemben 1926

The Cosmopolitan Nine (continued)

1.*-4 , 0

..,J 9" X 7"

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,

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Combined Panel Layout and Wiring Diagram, of theAmplifier Unit of the Cosmopolitan Nine.

soldered direct to the metal clips ofthe leak itself or the latter may bedamaged.

The small .00i-microfarad con-denser shunted across the loud-speaker jack may also be held inposition by the wiring.

The next point is the important

one of the choice of valves. ' For a6 -volt accumulator- the constructorcan do no better than use theOsram or Marconi DE8 L.F. fol-lowed by a DE5A or an LS5A forthe last stage.

For a 4 -volt accumulator we can'recommend the Mullard PM4 and

330

I)P425, whilst with a 2 -volt accumthlator the Cossor Stentor valves ofthe Mullard PM t L.F. and PM2 willgive excellent results.

The H.T. voltage .which will beapplied to the plates of these valveswill depend on the type of valeused, but we recommend the con-structor to 'buy . 'no -volt batten;tapped in steps of 2 or 3 .

this will -be. sufficient to supply allnine valves.

Accumulator H.T. AdvisableAn accumulator H.T. battery

should, if possible, be used, but if adry -cell type of battery is obtainedone of extra large capacity is prac-tically essential. It will be realisedthat the total plate current of ninevalves may be considerable, addingwith certain valves to something over50 milliamperes (.o5 ampere); acurrent which would put consider-lble strain on a small dry battery.

Although this unit has beendesigned primarily for the Cosmo-politan nine it can be, used withalmost any type of receiver providedthe latter does not already posses;two stages of L.F. amplification.The unit is an ideal amplifier for acrystal set.

Assuming that the two unitspreviously described are by now ingood working order all that remainsto be done is to connect the outputterminals of the second unit (con-taining the I.F. and detector valves)to the input terminals of this unit.

Make sure that the plate of the. detector valve of the second unit isconnected to the Input - " of thethird unit.

inserting the ValvesInsert the valves, turn the rheostat

till the filaments reach a suitabletemperature, and tune -in any stationon the first unit. Now adjust thetappings on the H.T. battery and thegrid -bias battery until the maximumvolume is obtained together with aminimum of distortion..

Reproduction should be excep-tionally clear and free from dis-tortion, and provided that: goOd usehas been made of the time during thelast two months to perfect the firsttwo units, the result should be anine -valve receiver .which brings inevery station with 'ease, volume andtrue reproduction.

Wireless Magazine.November1926

NWANNNNN:,:NNWANNZNNN: :NNilaN:4ANNNNNN'll;;N::NNiSF.,..NNNNa:: :%.0INNNNN::',/2W/ANTZMWMNZWEMN.

RADIO helps sport in the sameway that it helps any other

branch of human activity -13) mak-ing its appeal wide reaching. In-deed, properly directed, broadcastingcould easily become the most potentfactor in the encouragement of sport.

Listening to Talks !Even those who dislike sport listen

to talks about it-such a largenumber of people are psychologicallyincapable of switching off their re-ceivers for five minutes even when atalk that is intolerably boring (tothem) is being broadcast ! In timethe talks are first taken as a matterof course (that is, they are notactively resented), and later they arelistened to with real interest.

In almost every other country thathas an organised broadcasting ser-vice sport takes a more impor-tant part in the programmesthan it does in England. I donot refer only to the broadcast-ing of talks on sport, but to theinstantaneous transmissions ofactual events or of a " running "description by a qualified broad-caster.

Such broadcasts are in a stateof highly organised develop-

ment in t h cUnited States,for example, and" running " de-scriptions ofsporting eventsare a popularpart of man yprogrammes;they p r ov i d epeople who areunable to see theevent for them-selves with thenext best thing-an accurate accountby an expert observer on the spot.

English listeners who made specialefforts to do so were able to pick upmost of the broadcast of the Tunnev-Dempsey fight-an occurrence that isproof in itself that radio does helpsport by widening its appeal.

Andrew White, a well-known Americansports announcer, getting ready to broad-

cast the story of a baseball game.

tion of the thing as it goes on) mustlead many people to see futureevents for themselves rather thanmerely hear them. And anythingthat encourages an active interest insport can be said to help it. In anycase, it is much more satisfying tohear a thing than merely to read

about it.

Moreover, by meansof talks and instan-taneous broadcasts notonly is new sportstalent encouraged, butenthusiasts who are nolonger in the first flushof youth are kept intouch with a world fromwhich they would other-wise be shut out.

The mere fact of lis-tening to the broad-casting of 'a sports event(even without a descrip-

331

What a pity it is that theB.B.C. cannot broadcast "run-ning" descriptions of importantsports events in England. It isstrange that we, who are moreinterested in sport than anyother nation, have almost thepoorest sports broadcast servicein the world !

BM /PRESS.

BROADCASTING

SPORTS EVENTS

Thousands of people who were unable to witness

the Yale -Harvard boat race rowed on the Thames

River, near New London, Connecticut, in June,

heard Douglass Rigney broadcasting a description

from the course ; the photograph on the left shows

him talking into a microphone connected by

wireless to station WRMU.

The picture above shows American engineers

testing an amplifying outfit for the broadcasting

of the description of an important tennis matchdirect from the courts.

[Wireless Magazine. November 1926

A dinns think thaecookies mull staunmair than three days

afore they petrify.

THERE'S mony a mysteriousebullition o' concatenatin' cir-

cumstances, as oor young meeinstermaist beautifully remarrked the itherSawbath. Which is a rale guidmoothfu' tae starrt wi'. An' thoughat furrst A pit it doon juist becauseo' its inherent beauty, A see noothat it's a maist appropriate begin-ning.

The concatenatin' circumstancesaforementioned were : (s) lemonadethat had !oast it's ebullition (seeabove), no' mysteriously, but throughthe passage o' time ; (2) some cookiesI cudna dispose o' at ony price;an' (3) a tin o' preserved frooit thatA was feart was no' sae guid as itmicht hae been.

A accordin'ly suggested taeMaggie that tae encourage the wire -

less department o' ma floorishin'estaablishment in Clumtochty, anestaablishment which, A may saywi'oot boastin', hasna its equal inthe village (it bein' the only shop),A wad gie a bit party an' invitepoassible customers alang tae demon-strate, the wunners o' wireless an'persuade them, wi' the gentle taactsae symptomaatic o' the McNabs,that nae boos is hame wi'oot a wire-less set, purchasable coamplete atSandy McNab's, general proveesionmerchant an' wireless experrt.

" Thaat's a rale guid idea," saidMaggie. " :Tebbe All hear a bitmusic for yince."

A ignored her implied sarcasm, an'continued tae expound ma grreatidea.

" We'll hae tae be carefu',

332

A Wireless Story byRICHARD CAROL

Illustrated byWILL OWEN

Maggie. In the furrst place A dinnathink thae cookies wull staun mairthan three days afore they petrify,an', in the second, we maun hae arepresentative program."

Sae A lookit up the paper an' gota guid all-roon kind o' affair, illus-tratin' furrst-class music, commonmusical coamedy sort o' stuff, philoa-sophy, an' aagriculture.

Then A went roon tae about a dizeno' the non -wireless inhaabitants o'Clumtochty an' requested thepleasure o' their society tae light re-freshments, music, an' entertainin'coanversation.

Wad ye believe it? They a' ac-cepted a'most afore the wurrds wereoot ma mooth. A was awfu' pleasedwi' ma success, an', on ma wayhame, A estimated the proafit on theentertainment, aifter deductin' thecookies, etsaytera, at cost price, at noless than five pun.

They a' duly arrived, an' Maggie,followin' oot the instructions A hadread oot o' the wee book on etiquette,received them maist deegnified an'sat them doon on chairs, for thefurrst few, an' the coonter frae thepost-oaffice on twa soap -boxes forthe later arrivals.

Straicht -A cud see yin or twa cast -in' anticipatory glances at the dresserwhere the light refreshments weretastefu'y arranged; but A ignoredthe implication.

" Noo," A explained, assumin' acoanfident an' experrt aatitude," A'm gaun tae illustrate tae ye thewunner o' wireless an' its mony ad-vantages. Ye see A juist turrn upthe lichts an' rotate thae two discswi' a simultaneous movement, an'. . .

An' there was a maist awfu' howl.They lookit at ane anither, an' Afelt the openin' paragraph hailmissed. Hooever, A turned on the

Wireless Magazine. Novemben1926

aerial an' resumed ma flow o'oaratory.

" We are noo listenin' tae theaagricultural report. Angus McPhee,ye'll nae doot be interested tae hearthat faat soos are sellin' at a shillin'the pun."

" A'm no'," said Angus, " A haenae use at a' for soos."

This was no' a'thegither accordin'tae plaan ; but A juist smiled guid-naturedly an' let the coanversationbecome general for a few meenits.

Then a bit o' a concert was waftedtae their astoanished ears; an' A

cud see they were clearly affected.The furrst item was ca'ed a " violinsolo."

" Is it no' juist fine? " A mur-mured tae the assembled coangrega-tion.

" Och," said Miss McCosh, " it'sonly a skirlin' wee cockie-bendiefiddle at a'."

But the ithers were muckle im-pressed.

Next there was a bit o' oaratoryfrae a big denner what was bein'held in Glesgae.

The chairman got up and madea few verra laudaitory remarrksaboot the society, an' finally proposedits health, which was greeted wi'aacclamation. We cud hear theclinkin' o' glasses an' the cascadin'o' the liquor. Och, it was awfu'.

For Tammas McKay starrtedsmaackin' his lips in a maist in-deecently suggestive mainner, an' theithers took him up an' starrted taefidget an' cast maist pointed regardsat the dresser wi' its edible gar-nishin's.

Sae A nodded tae Maggie, an'straicht the atmosphere brichtened.They a' were maist obleegin' wi'their " ayes," an' accepted wi' nodso' unnerstandin' ma explanation thatthe drink was ceed " still " lemon-ade an' was verra poapular at a' thebig dances in Glesgae.

A' this time the music was con-tinuin', but ye cudna hear muckleowin' tae the snappin' o' the cookies.

When the edible garnishin's hadentirrely disappeared, A endeavouredto draw their thochts, which had beenpreeviously distracted, intae mairproafitable channels.

" Noo, you see," A declaimed," the great advantages o' thismoadern product o' human trial an'endeavour. You, Miss Kirsty, canlearn hoo tae kill the slugs that eatup hauf yer gairden."

" But, Meester McNab," saidKirsty, " A can dae thaat fine wi' ashovel wi'oot bein' tellt."

" Oeh," A retorted, " A was juistgie'in' ye an exaample." Then Acarried on quick as quick, for Adidna want ma illustrations coantra-dieted, " You, Miss Anderson, wadjuist rejoice in the wee talks onphiloasophy (that yin went doonfine). Again, there's the fairystories for the bairns at a suitablehoor, educational talks for them whadesires, as ye a' aucht tae desire,mental uplift. There's music et' a'varrieties. In fac', there's naebraanch o' arrt, or literature or

science or . . . or onythin' else, that'sno' dealt wi' by the wurrid's best ex-ponents. (A got that oot yin o'the papers.) A micht point oot thatA'm an experrt masel, an', as we're

a' guid freends, All fit ony o' yeup for-for a verra reasonable sum."

Hereupon Miss McCosh adjustedher bonnet, an' said:

" Weel, thank ye kindly, MeesterMcNab, an' All be awa'."

An' the ithers followed, juist fa'in'ower theirsels. A' except MissKirsty, wha hung baack.

" Weel," A said, smilin' tae maselin aanticipation, " is there onythin'A can dae for ye? "

" Aye," she said, saftly, an' Asmiled again.

" Dae ye think ye-ye-cud askme in ae nicht when they're playin'the uleleke. A've read aboot it-an' A wad juist lo'e tae hear ityince."

Ma net loss on the party, calcu-latin' the refreshments at cost, wasyin an' fowerpence happenny.

AV E LETSA DICTIONARY tells us that a " fan "

rk is something that gets the breezeup. Especially in Kilmarnock, whenthe authorities announce a new anti -pirate campaign.

A WOMAN prisoner- who escapedfrom jail has been recaptured throughthe agency of radio. Her husbandis understood to have become an en-thusiastic convert to wireless.

WHEN YOU AREIN TROUBLE

do not forget that the Technical Staffof the WIRELESS MAGAZINE is alwaysat your service to help you out of yourdifficulty and put you on the right path.

If you want advice on buying a set,address your query to the Buyers' AdviceBureau, not forgetting to mention howmuch, roughly, you wish to spend, whereyou are situated, what stations you wishto receive, and whether you intend to

use phones or a loud -speaker for listening -in.

In all other cases. address your lettersto The Editor, and not to the Buyers'Advice Bureau. Our address is theWIRELESS MAGAZINE, La Belle Sauvage,E.C.4.

When sending a query, write on oneside of the paper only, and do not forgetto enclose the coupon on page iii of thecover and a stamped addressed envelopefor a reply.

333

FRENCH listeners are having aperiodical talk entitled " FinancialNotes." Promissory Notes, we sup-pose, as usual.

THOUGH wavelengths are always inmetres, most aerials are still in yards.

THE ex -Maharajah of Indore hashad a wireless set installed. No doubtwith an indoor aerial.

A WOMAN listener complains thatthe B.B.C. talks on poultry make noappeal to her. Obviously she is oneof the few women who don't go tohen parties.

ONE of the Continental stations hasbroadcast a lecture on work. Somepeople think we get too many talkson these theoretical questions.

INMATES of lunatic asylums are nowprovided with wireless sets. And soare ordinary oscillators, worse luck !

A D.X. enthusiast complains thatmany of the American programmesare rather dull. Surely he does notexpect much spirit in them under Pro-hibition.

No other country can touch Britainat wireless, says a politician. Butthey all seem able to " touch " uswhere money is concerned.

If you are thinking of buying aset, you should read carefully the"Guide to the Best Valve Sets " onpage 346.

I WirelessMagazine.November:1926

\)(7111 re Series parallel(onneetions?An Easily -understood Article for the

T" precise significance of a" series " as distinct from a

" parallel " connection sometimesgives rise to unsuspected difficulty,such as, for example, when it becomesnecessary to compare the result of

Ri--/vvvvv.

(ir

R2'Vvvvv%

Fig 1.-Two Resistances in Series.

connecting two resistances or twocondensers in one or other of theseways.

There is something distinctlyanomalous and confusing in the factthat the effective resistance of tworesistances in parallel is less thaneach individual, resistance, whilstthe resultant capacity of two con-densers in parallel is the sum oftheir separate capacities.

At first sight the beginner isnaturally inclined to consider aseries co nection as similar, say,to a team of horses drawing a vehiclein tandem, whilst he similarly com-pares a parallel connection to a teamhauling side by side.

On this reasoning it appears thatthe result should be much the samewhichever arrangement is adopted.But in point of fact the resultobtained by a series connection inelectrical circuits is always very dif-ferent to that of a parallel arrange-ment.

Series Resistance

If, now, the resistances are con-nected in parallel, as shown in Fig. 2,we cannot assume that the currentsare the same in both, although it isevident from the diagram that thesame voltage E from the batteryis applied across both. ApplyingOhm's law to the resistance RI weknow that E = II RI, whilst for theresistance R2, the same batteryvoltage, E = 12 Rz.

Now the current I, supplied bythe voltage source E must be thesum of Ir and 12. Therefore

I .-- + 12 = E +;;).RI

Adding the two fractions/RI + R2 \ RI R2k RI R. E=I

RI d -R2The effective resistance is there-

fore the product of the two separateresistances divided by their sum.

Comparing the two arrangementsit will now be seen that for the

-IL, RIvvvvvvvvvv

R2

JHillE

Fig. 2.-Two Resistances in Parallel.

series connection, Fig. 1, only afraction of the applied voltage E isavailable for driving the currentthrough RI, the remaining fractionbeing spent in driving the same cur-rent through R2. Consequently thenet current must be less than ifeither RI or R2 were connected

Considering the case of two resist- separately across E.ances, RI and Rz, arranged in series With the parallel connection ofas shown in Fig. 1, the important Fig. 2, however, the whole voltage Epoint to note is that the same current is connected across both resistances.(I) must flow through both the If the source E is capable of main -resistances. The voltage across the taining its voltage constant, eachresistance RI is by Ohm's law Ri I, resistance carries as much currentand that across R2 is R2 I, and the as if it were connected alone acrosssum of these two voltages must be the source E, and the total currentequal to the applied battery taken is therefore greater thanvoltage E. either would be taken separately.

Consequently E = I (RI + R2) ; The two methods may be comparedor in other words the resultant with crowded traffic passing alongresistance is (RI + R2), the sum of a road. Fig. I merely adds a secondthe separate resistances. restricted passage R2 to the existing

334

Beginnernarrow road RI, and thus impedesthe flow of traffic. On the otherhand in Fig. 2 a by-pass road R2,is made available, thus divertingsome of the total traffic and relievingthe congestion on the road RI.

So far, the voltage source E hasbeen taken to be direct, but the resultis precisely the same if the sourceis alternating, provided that theresistances are non -inductive. Inthis case the traffic must be con-sidered as moving to and fro, eachvehicle reversing its direction atperiodic intervals.

Series and Parallel ImpedancesTurning now to the more difficult

problem of impedances connectedin series and parallel across an alter-nating voltage source, we will firstconsider the case of inductance coils,and to avoid complication it will beassumed that the coils have noappreciable ohmic resistance.

Such coils offer very small obstruc-tion to the direct or continuous flowof electrons set up by a battery con-nected across the coil. But theelectron stream in such a coil hasvery decided objections to makingsudden stoppages and reversals, suchas are caused by the application ofan alternating voltage. The morerapid the alternations of voltage,the greater this- objection becomes.

In fact the " choking " effect isproportional to the inductance Lof the coil, and if two coils of in-ductance Li and L2 are connectedin series, so that all the alternatingcurrent has to pass through bothcoils, the total resultant inductanceis Li + L2, the argument being

Fig. 3. -Condenser Across a Source ofFluctuating Voltage.

precisely the same as with resistances.Similarly if one of the coils acts

as a by-pass to the other, that is. inparallel with it, then the resultantinductance (just as with resistances)is less than either separately, being

equal to the product divided by thesum of their separate inductances(LI L2 ÷ Li + L2).

When a condenser is placed in analternating current circuit as shownin Fig. 3; the action of the source Eis to drive electrons into the upperplate A by withdrawing them fromthe other, B, and vice versa.

Voltage DifferenceDuring the half -cycle in which

electrons are flowing into the upperplate A, that plate becomes negativelycharged relative to the lower plate B,and a voltage difference is createdbetween the plates. This buildsup until the voltage difference is thesame as that applied by the source

E, whereupon there is a balance ofvoltages and the current momen-tarily ceases.

This stage is followed immediatelyby the withdrawal of electrons fromthe upper plate as the applied voltageis reversed.

Now the number of electrons thatare required to raise the voltage onthe condenser to the same value asthe applied voltage is proportionalto the size or capacity of the con-denser. Consequently the greaterthe capacity, the greater is the elec-tron flow or current.

In other words the impedance orchoking effect of a condenser is smallwhen its capacity is large, and viceversa, for a given frequency. This

WirelessMapzine,Abvember/926

result is the direct opposite of whathappens in the case of an inductancecoil, where, as we have seen, thechoking effect is in direct ratio tothe inductance of the coil.

Series CapacitiesWhen, therefore, two condensers

are connected in parallel, theireffective capacity is increased toCr + C2, and the impedance of thecombination is correspondingly re-duced. Finally when two capacitiesare connected in series, the effectivecapacity of the combination is lessthan either taken separately (beingequal to Cr C2 ± Cr + C2), whilstthe effective impedance of the systemis increased. M. A. L.

WHY YOU SHOULD USE

SQUARE -LAW CONDENSERS

QL; ITE a number of those who buildshort-wave receiving sets do not,

I am sure, realise the great advantagesof the square -law variable con-denser when properly used. Thisadvantage comes from the fact thatthis form of condenser does not givestraight-line tuning.

Dials and WavelengthsIf dial readings are plotted against

wavelength on a large scale on squaredpaper, it will be found that at thebeginning of the scale a large move-ment of the condenser will give asmall wavelength change. This isthe exact opposite to the ordinaryform of condenser, where, at thebeginning of the scale, a small move-ment of the condenser gives a largewavelength change.

With the square -law type thestraight-line tuning starts somewhereabout the tenth division in a scalegraduated to too divisions, and con-tinues to about the eightieth orninetieth division.

To take full advantage of thischaracteristic for short-wave recep-tion, a small -capacity condense:should be used and the inductanceso arranged that the most u ed partof the condenser scale is the low -reading end. In my own receiver I

have arranged the coil so that witha good variable condenser of .0002microfarad maximum capacity thetuning starts at 4o metres with thecondenser dial set at o.

The first eight divisions on thescale tune through one metre. Thenext metre is covered by about five

TABLE OF WAVELENG.THSAND FREQUENCIES

Metres Kilocycles

40 7,50041 7,31742 7,14343 6,97744 British amateur45 6,667 band 2 metres46 6,522 = 296 kc.47 6,38348 6,25o49 6,1225o 6,000

divisions, and then the straight-linetuning starts and the divisions arethree per metre. Thus I have a veryopen scale, the more open part beingwhere the frequency is highest.

In this regard it is useful to lookat a table showing the relationshipbetween wavelength and frequencyon these short waves, remembering

335

that a sharply tuned D.C. notespreads over a remarkably smallfrequency band,

One evening a short while ago Icounted ten amateur stations work-ing with D.C. notes between 44 and45 metres. They were, all but two,well separated, and it was possible toread them all without interference.Then a French amateur, using rawalternating current, started up andseven of the ten D.C. stations wereobliterated or rendered unreadable.

In the centre column is the tableto which I refer.

Necessity for Open ScaleThe necessity for using an open

scale on the condenser will be under-stood when it is seen that though theBritish amateur band only coverstwo metres from top to bottom, itcontains nearly 300 kilocycles. There-fore, in this band, well over a hundredmorse stations, using pure and un-modulated C.W., could work withoutinterfering with one another in theslightest.

On the other hand, only somethingover thirty telephony stations couldbe accommodated and only abouttwo stations using the saw -edgedA.C. that is inflicted on us by somecontinental stations. 5 Y M.

Wireless Magazine, Notvmben 1926

Installed in a NewYork theatre.

for the parchmentthat will do thesinging.

This revolutionary changein the theatrical art has beenbrought about by that enter-prising inetteur - en - scene,Florenz Ziegfeld.

After a number of years ofresearch, in which thesciences of electrical, radio,and sound engineering werelinked in a most remarkableway, out comes the " super-panatrope," a means of re-cording and reproducingsounds that is so perfect that

ELECTRICAL lungs and throatsof parchment will compose the

theatrical chorus of to -morrow, Atleast, there is a good indication thatthe chorus of- to -morrow will haveto maintain only the high standardof beauty, grace, and good dancingwhich it has established-it need nothave even a single voice! Electricallungs will provide the breath

throatactual

even trained dramatic andmusic critics could hardly tell thedifference between it and the origi-nal at the first demonstration inNew York recently.

The main problem the engineershad before them was perfect repro-duction of voices at great power.Reliability of the apparatus camenext, and perfect control by theorchestra leader followed.

ihe Chorus Girl's

ElectricalVoice!

" For the first time I am at last able tocomplement the splendid efforts of my choruswith incomparable voice renditions - thanks toscience! " said Mr. Florenz Ziegfeld, the well-known theatrical personality.

" It is my belief that this marvellous devicehas untold possibilities as an accessory to theother scientific aids now in the hands of themodern theatrical producer."

Great volume could be had by in-creasing ten -fold the power of anordinary low -frequency amplifier ofthe type used by the average listener.Even this was insufficient, and apower increase of several hundredtimes was studied, and applied to the'system. This overcame the ratherlarge absorption of :sound, by :the

CONNECTION TOMICROPHONE

MOTORSWITCH

U TOP1AT I CSTOP

The Record whence the Superpanatrope gets its Music.

scenery, seats,audience.

The finest vocal talent is used tomake the master records in the'quietof the recording studio, - the . finalpolished performance being also re-corded by means of a -new light -rayprocess which ensures the registrationof the most delicate shades of musicand voice.

carpet, and

336

even the

The process of making the recordsis an interesting one. The speed andflexibility of the light rays do awaywith the purely mechanical processrepresented in the old-fashionedgramophone records.

A tiny aluminium' cone, in. indiameter, at the centre of a smallcurved plate facing the music, is the

pick-up end of the apparatus.This drives a diminutivemirror, which oscillates moreor less violently, accordingto the intensity of the soundwaves. By thug oscillating,this mirror directs a series oflight rays more or less con-centrated- on a small electriccell which controls anothercircuit connected to a low -frequency amplifier, of thetype used in wireless circuits..It is this current, -upon

which variations of voice and'musical frequencies have beensuperinipoSed, which controlsaccurately an electric toolcutting the serpentine groove

in the soft wax -,record.. In generalappearance these records look likeregular phonograph records; but theyare far different in ,perforrnnce.

In 'the instrument, which is calledby the engineers the " super.pkna-trope," 'the records and .drivingmechanism are provided in duplicateto ensure positive performance.There are two units of everything--:

two records, two turn -tables, twomagnetic pick-ups, two low -poweramplifiers, two high -power ampli-fiers, two power sources, andtwo sets of reproducing cone" speakers."

Synchronised " Pick-ups"The two pick-ups arc synchronised

so that they are playing the samething at the same time, and onerecord can be instantly shifted to theother without break.

The reproducing process is sim-plicity itself. The needle thatfollows the grooves in the recordtransmits the vibrations to a magneticpick-up, where they are convertedinto electrical impulses varying as theintensity of the sound from theneedle. It is an easy matter. toamplify this electric current hundreds,or even thousands, of times, and ccn-duct them to loud -speakers that willreconvert them into sound waves.

Keeping TimeIn actual working, an operator is

in charge of the entire reproducingplant. He sets the records and thepick-up systems, and at a touch ofthe -button from the orchestra leader'sdesk the apparatus is started. Withthe downward stroke of 'his batonthe leader can direct hisorchestra, and keep timewith the " chorus girls " ina surprising manner.

FlexibilityThe flexibility of the device

is such that it can, at the willof the orchestra leader, supple-ment the orchestra, a solo, or

sing with thechorus accord-ing to plan.volume controlin the handsof the orches-tra leader per-mits him toadjust it to anyintensity front.a whisper to athunder roll!

Indeed, at ademonstra ti onrecently t'h crendition wasso powerfulthat the musiccould be heard.distinctly sevenmiles a Way!In the theatre,of course, thelimit is neverneeded, -al-though there isavailable atleast a half -kilowatt ofenergy in theamplifier system alone.

Just think What a wonderfulsystem this superpanatrope wouldmake to hitch on to a small single -valve regenerator!

Part

(Above). - Under thenetting are the elec-trical " voices "--twoloud -speakers that arepowerful enough to beheard seven milesaway out of doors.

(Left).- A view of theSuperpanatrope out»fit, showing the recti-fier and amplifier in

duplicate.

337

[-Wireless Magazine,Arovemben 1926

of the Superpanatrope Outfit.

Dressing Up in the StudioMENTION of costume in the

theatre reminded me how anybroadcasting studio once again

exemplifies the old truth, neverbelieved by men, that womendress to please themselves as-much as to attract the oppositesex.

I've noticed again and againthat concert artists arrive atthe studio to broadcast dressedjust as showily and expensivelyas if they were mounting aconcert platform in full View ofa large audience. And I my-self have never been able to gothrough the ordeal of broad-casting a ten minutes' talkwithout the moral support ofwearing my very nicest outfit.

I suppose it is that the con-sciousness of looking one's bestgives one 'self-confidence-thequality needed most of allbefore the microphone.

A. M. NI.

. You will be badly behind thetimes if you have not - read" More About the 1927 Five "-it is the first article in thisissue. Turn back to it now !

Wireless Magazine. Abvember 1926

Wireless "Lighthouse" at the Entance to the Firth of Forth; it was Built by the Marconi Wireless Telegraph Co., Ltd.

THE time is rapidly approachingwhen the systematic erection

of wireless " lighthouses " at numer-ous points along our coasts will havebegun. Already there are two such" lightliOuses " in constant operationat the entrance to the Firth of Forthand at South Foreland, in the Straitsof Dover. Others will follow in duecourse as the system of transmissionon which they are based becomesmore and more perfect.

South Foreland InstallationThe installation at South Fore-

land embodies certain technical pro-cesses which represent a markedimprovement on the design of theInchkeith installation in the Firth ofForth, and which are, in fact, chieflythe outcome of experience gained inthe operation of the latter installation.No doubt the third " lighthouse "will be a still more efficient affair.

It should not be long, however,

before we arrive at a stage .whenfurther improvement in design maynot reasonably be expected; or, atany rate, when the existing designwill be such as to justify the erectionof a wireless " lighthouse " at each ofthe many " danger points " withwhich our island coasts abound.

The function of the wireless " light-house " is, as its name suggests, tohelp ships to steer a safe course inthe neighbourhood of land. This,of course, is what the ordinarylighthouse does : but whereas thelatter is often rendered quite use-less during periods of foggy, or verymisty, weather, the former operatesin complete independence of " visual"conditions.

In fact, it is only when the ordinarylighthouse is put out of action bybad weather that the wireless " light-house " is of any very great value.

The number of occasions on whichthis occurs, however, is considerably

338

greater than most people imagine,particularly during certain monthsof the year.

The wireless " lighthouse " at Inch-keith consists of a " reflector," anaerial, and the necessary electricalplant for charging the latter. Thereflector is made up of a number ofshort vertical wires, arranged in theform of a parabolic curve, and theaerial is placed at the focal point ofthis curve.

Concentrating the WavesThe object of the reflector is, of

course, to concentrate the waves(emitted by the aerial) into a narrow" beam." The whole system isrotated by special machinery.

When in actual operation there-fore, the " lighthouse " sweeps thewaters of the Firth of Forth with arotating wireless beam, in much thesame way as the ordinary lighthousesweeps them with a beam of light

during normal periods of good visi-bility. It is interesting to rememberthat the fundamental nature of thetransmitted waves is the same ineach case. That is to say, boththe waves that comprise the beamof light and the waves that com-prise the wireless beam are etherwaves.

The chief difference between themis in length. Whilst the formerare sufficiently short to be capableof detection by that wonderful re-ceiving apparatus the human eye,the latter are _ so long that theycan only be detected with the aid ofan artificially -constructed receivingapparatus.

Principle of ReflectionThe principle of the reflector is, of

course, extensively employed in con-nection with all kinds of lightingsystems. We need not go to light-houses, 'searchlights, etc., to witnessits application. Perhaps a moreapt illustration is provided by theordinary bicycle lamp.

A bicycle lamp is invariably fittedwith some kind of reflector-usuallya metal one. Apropos of this it isinteresting to recall that SenatoreMarconi's first experiments in con-nection with the transmission ofwireless beams were conducted withcurved metal reflectors.

Wireless waves and light wavesbeing of the same fundamentalnature it was natural to assume thatthey should lend themselves to thesame method of reflection.

It was while conducting importantresearches during the late war thatSenatore Marconi developed the wirereflector. As previously stated thereflector at Inchkeith consists of anumber of short vertical wires,spaced at definite intervals apartand arranged in the form of aparabolic curve. (The actual lengthof the wires varies according to thewavelength used.)

It has been demonstra.ted, however,by recent experiments that betterresults can be' obtained with the aidof " plane " reflectors. That is tosay, instead of erecting the verticalwires in the shape of a curve, thereflector of the future will be flat.

It may be asked : How can awireless beam render any moreassistance to mariners than a beamof light during foggy weather, sinceboth are equally powerless to makethe coast visible ?

This question can only be answeredby a brief explanation of the very

ingenious method of signalling thathas been devised for wireless " light-houses." In the first place, when a" lighthouse " is in action the wholesystem revolves at a uniform speed.

" Raised" LettersAs it does so, the base of the aerial

makes contact with a large metalring on the surface of which are" raised " letters in the morse code.These letters are set round the ringat regular intervals, and it is onlywhen the aerial is in contact withthem that the aerial current is auto-matically switched on and trans-mission takes place.

In other words, a series of lettersis automatically transmitted as thesystem rotates through 36o degrees.Thus each letter represents a certaindirection of the beam.

When listening -in for the beam,therefore, the operator on boardship hears a certain letter at regular.intervals. He only hears one letter,-that is, the particular letter that isbeing transmitted as the beam sweepspast his ship. At any rate, he hearsonly one letter clearly. He mayhear others faintly, as the beamsweeps towards, and away from, hisship. But there will .be one pre-dominantly loud letter, which will behis " key " letter.

Each ship carries a special kind ofcompass card, usually called a " bear -

[-Wireless M agazine. November/926j

ing corrector," which is fitted withtwo movable pointers. Letters,corresponding to those sent out forvarious angles of the beam, areprinted all round the circumferenceof this card.

On receiving his " key " letter, theoperator sets one of the movablepointers to the corresponding letteron the bearing corrector. After aninterval he takes a second bearing,using the other pointer. The mid-point between these two bearingsindicates his real bearing from thelighthouse.

Another application of this branchof ' wireless consists in the use ofsteady beams for the purpose ofguiding ships and aircraft alongdefinite routes.

Parallel BeamsTwo parallel beams, " playing'

across the English Channel, forinstance, would be invaluable tocross -Channel shipping during foggyweather.

Ships going in one direction wouldfollow the path of one beam, whilstthose going in the opposite directionwould follow the path of the other,thus reducing the chances of collisionto a minimum.

A practical development of this" safety first " device may be an-ticipated in the very near future.

M. E.

TEN CABINET HINTS

i.-If you are a poor carpenterand want a handsome cabinet, buyone ready-made.

2.-Alternatively, buy the partscut to size and put them togetheraccording to instructions.

3.-If you are not fastidious asregards the cabinet, or if the set isto be placed in a dark corner, it iswonderful what can be done with anordinary sugar box. Sandpaper, floorstain and two coats of shellac varnishmake an amazing difference and,after all, the wood does not showmuch.

4.-Always buy the panel firstand build the box round it. It isnot safe to rely on the foot -rule.

5.-When sawing the wood, makeeach piece a trifle larger than it

339

%."1

need be. It is easy to plane a bitoff, but impossible to add any.

6.-Three-ply is quite suitable forthe back of the set, and strips ofthree-ply make useful stops for theedges of the panel.

7.-Three-eighths wood is best forthe bottom, sides and top, but if theset is to be of the American type, usestout wood for the baseboard, andsee that it is not warped.

8.-Glue (or "seccotine) and small" panel pins " make a neater jobthan screws or nails.

9.-Wood-beading is very cheapand gives a finish to edges that havenot been very carefully planed.

io.-Meccano strips make usefulsupports for a vertical panel usedwith a baseboard. H. P.

Wireless Magazine.November1926

ASTUDY of the circuit diagramwill show that this piece of

apparatus is a very useful adjunct tothe " gadgets " that every amateurpossesses.

As a crystal set, the instrumentwill give excellent results and willserve admirably as an emergencyreceiver when the valve set is out ofaction. It can always be relied uponto give clear reception of the localstation (or Daventry).

Because of the low -loss construc-tion of the coils and condenser, theefficiency of the instrument is high,and it would be hard to find a crystalset to beat it from the standpointof signal strength.

A feature that will appeal to manyreaders, however, is the use of theset as a wavetrap when attached toa valve receiver.

Cutting Out 2L0For those who, living in London,

find it difficult to cut out 2L0 andtune -in another station, a solutionto the problem of increasing theselectivity of their receiver will befound by connecting the aerial to theaerial terminal on the crystal set andthe earth terminal on the latter tothe aerial terminal of the valve re-ceiver, at the same time switchingthe crystal detector and phones outof circuit.

By tuning the coil of the crystalset to the wavelength of the inter-fering station the latter may beeliminated although the wavetrapwill offer no hindrance to the stationit is desired to receive.

All the controls on the combinationinstrument consist of a tuning con -

and

mbinedstal Setavetrap

Specially Designed, Built and Testedby the "W.M." Technical Staff

denser, a crystal detector, and adouble -pole single -throw switch,which cuts the phones and crystaldetector out of circuit and leaves theinstrument in a condition suitable foruse as a wavetrap.

By plugging -in a larger coil the re-ception of Daventry is rendered pos-sible and with the use of this largercoil the wavetrap portion of the setwill, in conjunction with a valvereceiver, separate Daventry fromRadio -Paris.

Components required for the con-struction of this set are as follows :-

.000s-tnicrofarad straight -line -fre-quency variable condenser. (Raymondor Ormond, Igranic.)

Dimic coil and holder, No. x. (L.McMichael, Ltd.)

Double -pole double -throw panel -mounting switch. (Dubilier or

4 terminals. (Belling -Lee type M orEastick.)

Crystal detector. (Wares R.)Ebonite panel, 9 in. by 7 in. by in.

(Siemens or Becol, Radion, Clayton.)Baseboard, si in. by 9 in. by I in..00 -microfarad fixed condenser.

(Dubilier or T.C.C.)Cabinet, American type. (Unica.)

NOTE :-The particular componentsshown in the photographs and allowedfor in the dimensioned layout are ineach case mentioned first.

The panel is a standard size sup-plied by most of the manufacturersspecified. This saves time and labourin cutting and trimming.

The panel should be laid flat on

Photograph showing Disposition of Components of Combined CrystalSet and Wavetrap.

340

the bench and positions for the holesmarked with a sharp tool. The hole.for the switch is marked more sharply.than the others.

The switch is mounted on thepanel with two 6 B.A. screws.

When the switch has been mountedthe variable condenser is fixed inposition. The angle at which thisis mounted can be seen from thephotographs.

The terminals and crystal detector(-an now be mounted and the panel

This unit is just the thing for everyowner of a valve set ; it can befor reception when the batteries from

the main set are being charged and,when the main set is in commission

again, it can be used for cutting outinterference.

Tested within a mile of 2L0 inconjunction with a three -valve set the

London transmission was cut out com-

pletely and Bournemouth tuned -in.

The unit can be converted for use as

a wavetrap by merely altering the con-

nection to one terminal and moving the

lever of a simple key switch.

fixed to the baseboard. Two round -headed brass screws are used for this.

Only two components are mountedon the baseboard, the coil -holder andfixed phone condenser. The positionsfor these can be seen in the photo-graphs and wiring diagram.

The wiring is rather more compli-cated than that of an ordinary crystalset, but if the wiring diagram isfollowed closely no trouble should beexperienced.

Soldered or ScrewedIt will be noticed that the connec-

tions to the terminals and crystal -detector sockets are soldered; thesecan be fixed by means of the nutsprovided.

The cabinet should be of theAmerican type, that used having ahinged top so that the coil was readilyaccessible for changing.

Plug in the coil and attach aerial,earth, and phones to their respectiveterminals. With the switch lever upthe local station should be tuned -inquite easily, a slight adjustment ofthe crystal detector only beingnecessary.

Wireless M a ga z November:19261

0005hIFD.)

:1,4111 TL CRYSTALDETECTOR

COIL 11OLDER

Wiring Diagram of the Combined Crystal Set and Wavetrap.

Details of Cabinet for Com-bined Crystal Set and

Wavetrap.

341

DETAILS OF THECOMBINED CRYSTAL

SET AND WAVETRAP

(Below).-Circuit Diagram of the Com-bined Crystal Set and Wavetrap.

:ONMECT TOAERIAL TERMINALOF VALVE SETWREN USW, ASA WAVE TRAP

CONNECT TOLAWN wntriUSING AS ACRYSTAL SET

Wireless Magazine. November:1926

14. I6) 16

3/87"

If

3"

Another photograph showing the construction of the CombinedCrystal Set and Wavetrap.

342

A i2

11Ii

lh

Panel Layout of the CombinedCrystal Set and Wavetrap.

When the set is used as a wavetrapthe switch lever should be down.This places the phones and crystaldetector out of circuit, leaving onlythe coil and condenser in.

The aerial should remain connectedto the top terminal, but the earthis removed and a wire from the aerialterminal of the receiving set is joinedto the earth terminal of the wavetrap.

OperationTo operate, tune the receiver to

the station it is required to cut out,then turn the wavetrap condenseruntil this station cannot be heard.This must be done carefully, as thetuning is very critical; the receivingset can now be used in the ordinaryway.

The wavetrap was tested within amile of London 2L0 on a three -valeset (detector and two low -frequencyvalves). 2L0 was easily cut out, andBournemouth received at very goodstrength in daylight.

[wireless Magazine. Novrmber1926

A &teal, Set forAND how much did this cost ? "

asked Beryl, holding the newvalve between her finger and thumbin a way that set my heart pulsingwith apprehension.

The box in which the valve hadbeen packed lay on the table, andthe box clearly indicated that it wasa power valve working a 12 ampere.Beryl had heard meyearning for one ofthese many times. Soit was no good improving on the truth.

" 22S. 6d.," I an-swered.

Beryl put the valvedown with an un-friendly lack of com-ment, and turned tothe door. The costof components i salmost the limit of herinterest in wireless.

" That makes 3 5s.you have wasted onwireless this month,"she said at last, " andyet you know howfaded the drawing -room curtains are.When it comes towireless you areutterly conscienceless,George."

I made a rapidcalculation, and

menter with all the components hewanted for six months. In fact,it very nearly convinced me that newparts were beyond my means for thefuture.

But one cannot even listen -inwithout spending an occasional shil-ling, and the only course was tot emporise.

really happy. I simply could nothave run to the expense of two ofthem !

" As a mat ter of fact," I lied, " Ionly bought that because it was suchan extraordinary bargain. I got italmost for nothing."

" How much ? " repeated Beryl, inan unyielding tone.

" A mere 5s." I said

ALMOST AS GOOD AS A MONOMARK!

This letter found its way to the Igranic Electric Co., Ltd., without delay.

thanked my stars that arithmetichad never been Beryl's strong point.

" But it will last for months," Isaid. " If you average out the priceover its probable life it costs lessthan a penny a day."

She gave me a quick glance.-" How much a day would new cur-

tains cost ? " she demanded." Oh, we'll probably be able to

run to new curtains next month,"I answered evasively.

" We'll run to them to -morrow,"she replied with decision. " If I buythe material, and have it made up athome, it won't cost more thanand with the rest you can take meto a matinee and stand me a cup oftea afterwards. I'll call for you atyour' office just before lunch." -

What that valve cost me, beforeI had finished paying for it, wouldhave provided an unmarried experi-

" I'll strike a bargain, dear," Iproposed after a few days' thought." We will keep a list of all the wirelessstuff I buy, and at the end of eachmonth you shall have chocolates, ora pair of gloves, or a sealskin coatto the same value."

Beryl masked her surprise andagreed gratefully.

" We'll start with that black boxaffair you brought home last night,"she said.

" Oh, the new high-tension. That'snot a new part ; it is only a renewal."

" But it's not worth an argument,dear," she returned sweetly. " Howmuch did it cost ? "

Now that H.T. was a real H.T.of reliable make, adequate voltage,and a good deal more than ordinarystrength. I had been coveting itfor months before I had made upmy mind to blow the price and be

343

-and Beryl noteddown 5s.

That was my firststep on the downwardpath. If it had notbeen so easy it mightnot have mattered.But to have got ahigh-tension batterylike that one, andpeace, for only 5s.above the usual price,was too great a temp -tation.

By the end of themonth. I had found itnecessary to buy mostof the parts for anew five -valve circuit.And Beryl's list hadmounted to 16s. 6d.

She seemed satis-fied.

Next month a coupleof valves "went west,"and I burned out anancient L.F. trans-

former. However, new ones werea decided improvement, and 75. 4d.over and above the market price wasnot much to pay.

" Things have dropped in pricequite amazingly, if you know whereto buy them," I explained.

And so for a spell wireless anddomestic bliss flourished side byside. I felt that I had made a dis-covery second only in importanceto the thermionic valve. I beganto study morse in earnest, and madeenquiries about a transmittinglicence.

But I might have known that itwas too good to last.

I had forgotten Beryl's brother.He dropped in one night, and

despite his casual manner, I fanciedI detected a wink to his sister thathinted at a previous understanding.

" I'm going to add a couple more

Wireless Magazine.Novemben1926

A Cheap Set for Jim! (Continued)

valves," he said, " and I want toask you about the kind of thingum-mies to buy, and how to fix them up.In fact, I wondered if you'd give mea hand at the job."

" Delighted," I assured him, in-sincerely.

" Well, first of all, what parts shallI have to get ? Here's the circuit."

I looked at it, and once again Ifelt vaguely suspicious. It was thevery circuit I had just put togetherfor myself.

" There are two of these interme-diate transformers," he pointed out." Are they outrageously expensive ? "

Then Beryl butted in." Everything has gone down

amazingly, Jim," she said, " pro-vided you know the right places togo to. You must let George getthe things for you. He's used to it.I can tell you what it will cost."

From the interior of the blueginger -jar on the sideboard she pro-duced four lists, and while I lookedstonily at the decanter that Jim wasgently emptying, she read :

Two intermediate frequencytransformers, 4s. 3d. ; square -law con-denser, is. 9d. ; L.F. transformer,

2d. dull -emitter valves, 2S. 7d. ;

dual rheostat, 7d. ; poten-potenti

" Look here, Beryl," I interrupted," some of those were special prices.

.e10.**NrAVs"\PaNes`V"NeMPM,MraNel

DO YOU WANTTO BUY A SET ?

We shall be glad to advise youas to which types of sets are thebest for your personal use.Tell us how much, roughly, youwish to spend ; where you aresituated; what stations you wishto receive ; whether you intend touse phones or a loud -speaker,and we will advise you as to thegeneral lines of sets that willanswer your purpose.Send your inquiry with coupon(p. Ui cover) and stamped addressedenvelope to-

" Buyer's Advice Bureau,"WIRELESS MAGAZINE,

La Belle Sauvage, E.0 .4.

A friend of mine was able to put mein the way of a few things."

" By Jove, I should think he was !"exclaimed Jim.

I have never really liked Jim." You don't mean to say," Beryl

demanded, in an aggrieved voice," that you wouldn't go to as muchtrouble for Jim's sake as you wouldfor your own ! "

" No, no," I admitted. " I'll dothe best I can, of course."

Jim seemed pleased." But look here, old dear," he

added, as though with sudden in-spiration, " I know you never stickto the same circuit for more than a fewweeks together. How would it beif you let me have that one you'vejust put together ? I'll hand overwhat it cost you, and then you canstart on the next box of tricks witheverything fresh from the makers."

He must have seen a certain lackof enthusiasm in my expression,for his eyes travelled from my faceto his sister's.

" Of course George will," saidBeryl. " It's a splendid idea. And,George dear, as you are being so niceto Jim, I'll only take half the priceof the new things you buy thismonth ! "

My lips parted for speech but -well, what was there to say ?

And that explains why I am satis-fied with a detector and one L.F.amplifier these days. H. P.

t`^neP'\ r'" \e,`Nr^1rW1ePWrW' r"Nr" \ \

WHERE TO PUT THE FILAMENT RHEOSTATStAnrAfted oted red \

THE principal function of a fila-ment rheostat is, of course, to

regulate the amount of currentflowing through its particular valvefilament. This it would do equallywell whether it were connected inseries with the filament betweenthis and the negative terminal of theL.T. battery, or in series with thefilament between it and L.T.positive.

Another FactorThere is, however, another factor

to be considered. This is the voltagedrop across the rheostat winding.There will always be such a voltagedrop as a rheostat can only be usedwhen the voltage of the L.T. batteryexceeds that actually required by thevalve.

For instance, suppose a 6 -volt

accumulator is used to supply currentto a valve requiring only four volts(as is often the case) there must be avoltage drop of two volts across theused portion of the rheostat when thisis properly ad usted.

For Grid BiasThese two volts can often be utilised

to supply grid bias to amplifyingvalves and thus save the necessity ofa special battery for the purpose. Itshould then be connected in thenegative lead to the valve filamentand the return grid lead of this valvetaken direct to L.T. negative.

It happens, however, that the gridbias will then be altered whenever thefilament voltage is readjusted sothat it is really better not to usethis method when a grid -bias batteryis employed (as when a considerable

344

G.B. voltage is necessary), in whichcase the rheostat can be put on thepositive side of the valve filament.

L.M.T.

A LECTURE on the use of water wasgiven from a German station theother day. Probably part of an edu-cational course for milkmen's ap-pren tices.

UNNECESSARY items.-The recenttalk from Aberdeen (of all places) oncollecting old silver.

TnE B.B.C. says that, 62 per cent.of its programmes consist of musicalitems. We must listen out for someof them.

WIRELESS has brought Londonwithin hearing distance of New York,says an American. It seems prettyhard luck on the Londoners, but Isuppose they will get over it.

Wireless Magazine, November:1.926

- C=3"

IMP OVE YOU RECEPTI NOne-, Two-, and Three -valve Amplifier Circuits

Where transformers areshown a suitable ratio is4 : r, while any availablemake of resistance -capa-city -coupling (R.C.C.) unitcan be used. Two types ofjack are shown-the double -contact jack (D.C.) and thesingle open -circuit jack(S.O.C.). Valves used afterthe resistance -c o up lingunits should be of thespecial type made for thepurpose.

A n amplifier made onthe lines of the circuitshown here is especiallysuitable for improving theresults obtained from a crys-tal or one- or two -valvereceiver. It is simple andinexpensive to build up.

The inclusion of thegrid -biasing battery is op-tional, but will be founduseful if the amplifier isemployed for loud -speakerwork.

D.C. JACK

./'A

R.C.C. UNIT) 5.0.C. JACP;

11

111 \' ememilEssavq,ms.

C MFD.

If you prefer a little more volume than'is obtainable from a one -valve amplifier,at the same time keeping signals as dis-tortionless as possible, a two -valve amplifierwired up as shown will be found verysuitable for coupling to your existing head-phone set.

Jacks are arranged so that either one ortwo valves can be used at will-dependingon the volume required-but when only thefirst valve is employed the rheostat of thesecond valve should be turned to the offposition or the filament of that valve willbe burning unnecessarily.

The circuitshown here isvery suitablefor use in anamplifier to becoupled to anexisting H.F.and detectororone -valve de-tector set andwill givereally goodvolume with-out distortion,providing sig-

R.C.C.

R.C.C. UNIT)

D.C. JACK

J

nals are al- GB ma GB --W- GBready at fair + Ti--strength.

--FFheadphone

Jacks are provided so that either two or three valves may be utilised at will, enabling the volume to beadjusted to suit the loud -speaker in use.

. e

i

_i: .=3" - r : : ., :,- .r _: '. - -414-119-4111S

M FD.eAui-

MilliIOURerr CERN iHT

345

rWireless Magazine, Abvemben1.9261

Guide to the Best Valve Sets

0®®6.6.E6

THIRD PART

The most detailed and themost comprehensive list ofBritish valve sets, speciallycompiled by E. REDPATH

IN order to make this guide as helpfulas possible to each prospective owner

of a set, a few preliMinary remarksregarding the general characteristicsand capabilities of the different types ofset are given at the beginning of eachsection.

Conservative EstimatesReaders will appreciate that as recep-

tion conditions will vary considerably, aconservative estimate of performance isgiven, based upon, average conditions-both atmospheric and geographical-andthe use of an aerial -earth arrangementof average height and efficiency. Underfavourable conditions the performancesindicated will be improved upon quitereadily.

To save space and needless repetition,a simple code will be employed todescribe the different valve combinations ;that is, HF-D-2LF represents a four -valve set having one high -frequencyamplifying valve followed by a valvedetector and two low -frequency amplify-ing valves. Similarly, C-LF representsa crystal detector plus one low -frequencyamplifying valve. An asterisk (*)against or above one of the figuresmeans that the valve so marked is" reflexed," and therefore functions ina dual capacity.

PricesWith a few exceptions, prices through-

out are given in two forms. First, theprice of the set alone (including Marconiroyalty of 123. 6(1. per valve holder), asthis will interest readers who alreadyhave phones or loud -speakers, batteries,valveS, etc., and, secondly, an " "price for the set (including royalties) andaccessories, which will be specified asfollows :-

A-Accumulator or suitable dry -cellbattery.

13-High-tension dry -cell battery.V-Valve or valves, as required.E-Aerial equipment (included in some

cases).T-Telephones-one pair as a rule.S-Loud-speaker.Thus " Price {so " is the price of the

particular set plus Marconi royalties.

SAVE YOURSELF TIME ANDTROUBLE

by writing to US for further particularsof any sets in which you are particularly

interested.

At the end of the description of eachset you will see a reference number.If you are interested in several three-valvers, say, send us a postcard bearingyour name and address and the numbers

4 the sets of which you require moredetails-we will see that the manufac-turers do the rest.

" Price (ABVS) ZIS " is the " all -in "price of set, royalties, L.T. battery, H.T.battery, valves, and loud -speaker.

Liable to AlterationAlthough the greatest care has been

taken in ascertaining the prices and inquoting them in a uniform manner inorder to facilitate ready reference andcomparison, the prices shown are notto be regarded as an offer or quotationby the manufacturers.

ONE -VALVE SETS

T Fl IS type of set may profitably beinstalled in place of a crystal set

where increased volume from the localtransmitting station or the use of addi-tional pairs of telephones is desired.

It will also enable satisfactory resultsto be obtained over much greaterdistances, say up to so miles from amain station and too miles from 5XX(Daventry).

Not recommended for use with a loud-speaker, but at distances not exceeding4 or 5 miles a modest volume for a quietroom may be obtained from a smallloud -speaker without undue use of thereaction or volume control provided.

. The initial cost of a set of this typeis low ; it is simple to operate and

346

economical in upkeep. If a low -con-sumption valve is fitted, the filament maybe heated by means. of a suitable dry -cellbattery or quite a small accumulator,which will not require recharging veryfrequently.

The high-tension battery need not, asa rule, exceed 45 to 6o volts, and shouldgive satisfactory service for severalmonths.

C .A .0 . UNI-VALVE. C.A.C. ValueDistributing Co., Ltd., 10, RangoonStreet, Crutched Friars, E.C.3.A simple and easily operated single -valveset in flat case (polished oak ormahogany) with interchangeable coilscarried in a two -coil holder mountedupon the side of the case. Operation inthis case involves merely the adjustmentof one dial and the relative poSitions ofthe two coils, controlled by means of theextension handle. Coils for the normalbroadcast wavelengths are supplied willsthe set. The valve, also all terminals andcontrols (except two -coil holder), arecarried upon the ebonite top panel.Quite satisfactory receptio over theusual ranges is readily obtained.

PriceAll -in price (ABVET)

Ref. W. M . os

FELLOPHONE SUPER-ONE.Fellows Magneto Co., Ltd., Cumber-land Avenue, Park Royal, N.W.10.Contained in an open -fronted blackleatherette cabinet, the Super -One set isboth neat in appearance and efficient inperformance. Designed to enable goodphone reception to be obtained fromstations at considerable distances, thecontrols are nevertheless simple, andcomprise a main tuning knob withpointer, a reaction knob, and filamentrheostat knob. For simplicity all ter-minals and controls are mounted ,uponthe vertical front panel, whilst the valveand coils are enclosed, and accordinglyprotected. A Fellows coil is suppliedwith each set to enable the normal broad-cast wavelength range to be covered.Additional coils, for which provision ismade, enable Daventry or other long -wave stations to be mil-AN:ed.

Price 4.2--to-o.All -in price (ABVET)

Ref. W.M.108

CARPAX CABINET. Carpax Co.Ltd., 312, Deansgate, Manchester.This set embodies the same circuitarrangements as the Fn type described

Carpax One -valve Set.

below, but the cabinet design gives theobvious advantage of, an enclosed valVeand coil. The standard set, as illus-trated, is in black " pebble -grained "cabinet, and the whole presents a veryneat appearance. If desired, it may alsobe obtained in a mahogany cabinet.

Price £3-6-o.All -in price (ABVT)

Ref. W.M.10-,-

CARPAX F 1 I . Carpax Co., Ltd.,312, Deansgate, Manchester.An extremely simple and economicalsingle -valve set of the box type withhorizontal panel carrying the valve, coil,terminals and necessary controls, which,in this case, comprise a condenser dialand filament -rheostat knob. Coil for thenormal broadcast wavelengths (250-5oometres) is supplied with the set, and theuse of additional coils enables the wave-length range to be extended. The

Carpax Box -type Set.

Accessories are specified as follows :-A-Accumulator or suitable dry -cell battery.B-High-tension dry -cell battery.V-Valve or valves, as required.E-Aerial equipment.T-Telephones.S-Loud-speaker.

makers claim that, under reasonablygood conditions, satisfactory telephonereception from distant stations may beobtained.

Price L:2 -8--o.All -in price (ABVT) 4'5-7-6.

Ref. ViT.M.to6

TWO -VALVE SETS

11H ERE are two familiar arrangementsof this type of receiving -set. The

first comprises a high -frequency amplify-ing and a detector valve (HF-D) in-tended for long-distance telephone recep-tion (say 15o miles from a main station).

The second, and much more populararrangement, comprises a detector valve(provided with reaction or volume con-trol), followed by a low -frequency ampli-fying valve (D-LF), and is capable ofgiving satisfactory loud -speaker results atdistances up to 15-2o miles from a mainstation or 50-6o miles front 5XX.

B.S.A. B.S.A. Radio, Ltd., SmallHeath, Birmingham.

B.S.A. Two-valver.

D-LF. Extreme simplicity and neatappearance, together with a good loud-speaker performance from nearby broad-casting stations, have been the principalobjects of the designers of this set.Embodying a patented B.S.A. tuningunit, the controls are very simple, asmay be, gathered from the illustration,and the overall neatness is maintained bythe provision of a multiple battery cord,permanently attached to the set, with allbattery connections clearly 'labelled. Anew B.S.A. power valve is used in theamplifying stage, and an arrangement for

[Wireless Maka±ine,November:1926

giving correct adjustment of grid poten-tial ensures good tonal quality. Thecomplete set is enclosed in a mahoganycabinet with front panel of oxydisecl metalinstead of ebonite: A small master;switch, shown on the panel, simul:taneously disconnects both batteries.

Price L;8 o o.All -in price (ABV)

No -18-o. Ref.plinth for battery box, extra

W. M.234

A.J.S. Symphony II.

SYMPHONY II. A. J. Stevens &Co. (1914), Ltd., 122/124, CharingCross Road, W.C.2.D--LF. A handsome, all -enclosed two -valve set of particularly neat and artisticappearance. The cabinet is well madeof mahogany and provided with batterycompartments at each end, the batteriesthemselves being readily accessible whennecessary. The controls are two innumber, one for tuning purposes andone for volume control. Plug-in coils ofthe well-known A.J.S. type are pro-vided for the normal and long -wavestations, whilst additional coils may beobtained to cover the complete wave-length -range of from 8o to 4,500 metres.In lieu of the usual dials on the frontpanel it will be noticed that the adjust-ment of the controls is indicated bymoving scales, which are visible throughapertures in the panel. Each selectorhas two scales, one numbered and oneleft blank to have the name or call -signof any particular station marked to facili-tate subsequent adjustment.

All -in price (ABVS) L;17 -to -o.Ref. W.M.227

EDISON BELL ERA. Edison Bell,Ltd., Glengall Road, S.E.15.D-LF. A particularly neat and compactset fitted in polished cabinet with foldingdoors and measuring overall 12in. by gin.by Sin. A vertical panel, immediately be -

Edison Bell Two -valve Set.

If you want further particulars of any of these sets send a postcard to US and save yourself trouble

347

Wireless Magazine, November; 1926

Guide to the Best Valve Sets (Continued)

hind the doors, carries the simple operat-ing controls, comprising two main dials(tuning and reaction adjustments), aerial,earth and telephone terminals, and an on -and -off switch. All battery terminals areat the rear of the cabinet, provision beingmade for the application of different volt-ages to detector and low -frequency ampli-fying valve, the correct grid bias for thelatter being obtained by a special arrange-ment instead of the usual additionalbattery. The set as supplied will tunefrom zilo to Soo metres and from goo to1,600 metres, thus enabling both normaland long -wave broadcasting to bereceived.

Price Z3 -13-o.Ref. W.M.233

COMPACTUM. Edison SwanElectric Co., Ltd., 12315, QueenVictoria Street, E.C.4.D-LF. This set, of rather unusualappearance, has all external parts made

Compactum Two-valver.

of moulded insulating material, with theobject of enabling a compact andefficient receiver to be produced at alow price. Excellent loud -speaker repro-duction is obtained at distances up to25 miles from a main station, whilstwith telephones greatly increaseddistance may be covered. The two valvesare mounted on top of the centralcolumn, which forms a casing for thelow -frequency transformer and its con-nections. The circular base on the setcontains the variable condenser operatedby a radial lever, as also are the othercontrols, namely, the reaction adjust-ment and the filament rheostat. Plug-incoils are employed, so that, by the pro-vision of appropriate coils, the completerange of wavelengths may be tuned -in.

Price £4 -o -o.All -in price (ABVES) Zr1-8-11.

Ref. W.M.233

FELLOPHONE. Fellows MagnetoCo., Ltd., Cumberland Avenue, ParkRoyal, N.W.10.HF-D. Intended for satisfactory phonereception from near or distant stations,this set comprises a sloping ebonite panel,carrying all controls, terminals andvalves, fitted to a well -finished mahoganycabinet. There are two tuning dials, oneadjusting the aerial circuit and the other

Accessories are specified as follows :-A-Accumulator or suitable dry -cell battery.B-High-tension dry -cell battery.V-Valve or valves, as required.E-Aerial equipmentT-Telephones.S-Loud-speaker.

the output circuit of the high -frequencyamplifying valve. A reaction control isalso provided, and a single rheostatknob which controls the filament currentof both valves. Special sockets are fittedto take additional coils when it is de-sired to extend the wavelength range.These sockets are normally short-circuitedby means of plugs supplied. The set isguaranteed to receive any B.B.C. stationand, with the addition of suitable coils,several Continental stations.

Price Z3 -13-o.All -in price (ABVET) Z7-17-6.

Ref. W.M.zz4

FELLOPHONE LITTLE -GIANT.FeUows Magneto Co., Ltd., Cumber-land Avenue, Park Royal, N.W.10.D-LF. Contained in a neat leatherette-'covered case with horizontal top panelcarrying all terminals, controls andvalves, this is a low-priced but eminentlyserviceable set capable of giving goodloud -speaker volume over the usual dis-tances. The operation is simple, the ad-justments comprising one main tuningknob, with pointer moving over scalemarked upon the panel ; reaction orvolume -control knob, also with pointerand scale, and a single filament rheostatwhich controls both valves. As supplied,the set tunes over the normal broadcastwavelengths, but additional coils may beplugged into a socket provided to enableother wavelengths to be received. Suchdetail as provision of terminals for gridbattery has not been overlooked.

Price Z3 -13-o.All -in price (ABVES) Z6 -13-o.

Ref. W.M.223

B.R.C. British Radio Corporation,Ltd., Weybridge, Surrey.D-LF. A well -made and very service-able set which, by means of a patenteddevice, enables a wide range of wave-lengths (that is, zoo to 2,000 metres) tobe covered without additional coils. Thetuning adjustments comprise a maintuning dial which is to be operated inconjunction with the wavelength -rangeswitch. Reaction or volume control isprovidcd, and a separate filament resist-ance controls each valve. All terminalsfor battery and aerial -earth connectionsare at the back of the cabinet. Toensure satisfactory loud -speaker volume,power amplification is employed and asuitable power valve is included in theequipment supplied. A twelve months'guarantee accompanies each instrument.

Price Z.7 -1-5-a.All -in price (ABVS) £12-12-0.

Ref. W.M.223

348

B.R.C. Two -valve Set.

TWO -VALVE ANDCRYSTAL SETS

NDER this heading, several differentU arrangements are possible, but ex-perience has indicated that two only arereally satisfactory and therefore popular.

The first of these, comprising a crystaldetector followed by two low -frequencyamplifying valves, is suitable for usewithin crystal range of a broadcastingstation, but has the advantage of enablinglull loud -speaker volume to be obtained.At the same time the arrangement is assimple to operate as an ordinary crystalreceiving set, the only additional adjust-ment or control being the movement ofa switch or knob to turn the filamentcurrent of the valves on and off.

Brownie Two -valve and Crystal Set.

BROWNIE. Brownie Wireless Co.of Gt. Britain, Ltd., Nelson Wks.,Arlington Road, N.W.1.C-2LF. This combination receivercomprises the popular Brownie No. 2

crystal receiver and a specially designedtwo -valve low -frequency amplifier, and isintended to enable good loud -speakerreception to be obtained from broadcast-ing stations within crystal range. Thecrystal set is of novel design, and ismade of one solid moulding, neat inappearance, strong, and well finished. Ithas a normal wavelength range of from

about 300 to 600 metres, according to theaerial with which it is used, and bymeans of an additional coil, which fitsinto the coil socket provided, receptionfrom 5XX is obtainable. The amplifierunit, which has been specially designedto enable the crystal set to be fitted andconnected easily,- is also in a mouldedcasing to match, the two valves beinghoused in the moulding by means of anti.microphonic sockets. Battery connec-tions are at the back of the amplifier,and both valves are controlled by a singlerheostat. The amplifier may be obtainedas a separate unit and used with anycrystal or single -valve set,. the actual con-necting up being extremely simple. Inthe complete set the adjustments comprisemerely the setting of the crystal detec-tor, turning on or off the valves, and theadjustment of one tuning control.

Price (crystal set complete andamplifier) £3-13-6. Ref. AN'.NT.2 T 6

THREE -VALVE SETS

CIF three -valve receiving sets there arethree serviceable types available.

First, the arrangement consisting oftwo high -frequency and a detector valve(iHF-D), which is particularly suitablefor selective long-distance reception ontelephones, but not really suitable forloud -speaker operation. Performance ofthis kind is not in any great demand, andaccordingly not many sets are manufac-tured with this circuit arrangement.

Secondly, there is the combination ofdetector valve (with reaction), followed

two low -frequency amplifying valve(D-zLF), which gives powerful loud-speaker results from a main stationwithin 5o or 6o miles and, with carefuladjustment, reasonable loud -speakervolume over much greater distances.Satisfactory reception from Daventry isobtainable up to zoo miles, whilst theoperation of this type of set is quite assimple a matter as in the case 'of a single -valve -with -reaction receiver.

The third arrangement, which may beconsidered the average of the first andsecond above mentioned, comprises oneH.F. valve, detector valve and L.F. valve(IIF-D-LF). The high -frequency. valveensures satisfactory range and increasedselectivity, and the low -frequency valvefollowing the detector ensures a strengthadequate in most cases for good loud-speaker volumes at distances up totoo/tzo miles from a main broadcastingstation and zoo/25o miles from 5XX.

It is to be noted that this type 'of setwill permit a selection of programmes tobe received provided that (a) the receiveris situated at least a few miles from thelocal broadcasting station, and (b) thatthe difference in wavelength between thelocal and the desired station is sufficientlygreat for the degree of selectivity pro-vided in the set.

SUCCESS SUPER -THREE. Beard& Fitch, Ltd., 34/36, AylesburyStreet, E.C.1.

Success Super -three.

D-2LF. A neat; compact, and very effi-cient set designed to give loud -speakerreception over considerable distances and,at the same time, to be as simple as pos-sible in operation. :A special method ofobtaining reaction is incorporated, ensur-ing smooth control with consequent bene-fit either in the way of distant receptionor of maximum volume without distortion.By means of interchangeable induc-tances, a wavelength range of 402,50o metres may be covered, sothat, under favourable conditions,the short-wave American transmis-sions can be received. The set isassembled ill a well -finished, open -frontwalnut cabinet, and the controls (tuningand reaction dials, filament rheostat andloud -speaker jack only) are convenientlyarranged upon the vertical front panel.Access to valves and interchangeable coils,which are completely enclosed within thecabinet, is by means of the hinged lid.

All -in price (ABVS) £17 -to -o.Ref. NV.NI.325

A COMPLETE INDEXTO THIS GUIDE TOTHE BEST VALVE SETSAPPEARS ON PAGE 355

SYMPHONY III. A. J. Stevens &Co. (1914), Ltd., 1221124, CharingCross Road, W.C.2.D-2LF. Of similar external appear-ance to the two -valve receiver alreadyreferred to, this set comprises an addi-tional low -frequency amplifying valve,thereby ensuring full loud -speaker volumefrom a limited number of main stations,

A.J.S. Symphony III.

Wireless Magazine. Now?? bet:19261

and, by changing the plug-in coil for alarger one provided, from the high -power station 5XX. In both this andthe former receiver a special tuningarrangement is incorporated, togetherwith condenser reaction, the whole prov-ing very effective, whilst the reaction -orvolume control, in particular, is smoothand certain. A good degree of selectivityis also obtainable, and the makers claimthat, used in conjunction with a standardtooft. aerial, in the Midlands good loud-speaker reception was obtained from thehigh -power station and from London,Birmingham, Bournemouth, Manchester,Stoke, Nottingham, and Paris. The setshould appeal particularly to thosedesirous of having an efficient andartistic home -entertainment set whichis easy to operate and economic tomaintain. -

All -in price (ABVS)Ref. NV.M.33o

FELLOPHONE GRAND. FellowsMagneto Co., Ltd., CumberlandAvenue, Park Royal, N.W.10.IlF*-D-LF. A handsome cabinet setincorporating a three -valve reflex circuitby means of which the results obtained

Fellophone Grand.

are comparable to an ordinary four -valveset. The cabinet itself may be obtained inJacobean or Sheraton style. The doubledoors provide complete protection tovalves and control panel, whilst, in thebase, ample space is available for stowageof batteries. The standard set can betuned to receive from all stations on thenormal wavelength band, whilst addi-tional loading coils may be plugged -inwhen reception from 5XX is desired. Thetuning operations involved are fairlysimple, the actual controls being practic-ally identical with those of the FellophoneSuper -Three described on the next page.

Price Z.12 -45-o.All -in price (ABVET) £15 -to -o.

Ref. W.M.325

B .R .C. British Radio Corporation,Ltd., Weybridge, Surrey.D-zLF. This extremely serviceable setincorporates a special patented control bymeans of which all wavelengths betweenzoo and 2,000 metres may be covered with -

If you want further particulars of any of these sets send a postcard to US and save yourself trouble

349

Wireless Magazine. November 1926

Guide to the Best Valve Sets (Continued)

B.R.C. Three -valve Set.

out the necessity for coil changing. Ofneat and symmetrical appearance, thecomplete assembly is contained in a well -made walnut cabinet with all con-trols, comprising the main tuningdial, wavelength range switch, re-action or volume control, and fila-ment rheostat knobs, mounted uponthe vertical front. The installation andoperation of this set are simple andstraightforward, whilst the results ob-tainable show it to be efficient and capableof giving very satisfactory loud -speakerreception over the usual distances, whilst,with a little careful manipulation, recep-tion from stations at considerable dis-tances may be obtained at moderate loud-speaker strength or, of course, at adequatestrength in telephones.

PriceAll -in price (ABVES) Z.17-17-0.The same receiver can also be supplied

in totally -enclosed walnut cabinet withspace for batteries, etc.-price ..25-10-0.

Ref. W.Ni.3i9

DUODYNE III. Peter Curtis, Ltd.,11, Red Lion Square, W.C.1.214F-D. Specially designed for long-distance reception on telephones, thisthree -valve set comprises two high -frequency amplifying stages (onetuned), followed by a detector valve withprovision for reaction to the anode cir-cuit of the preceding valve. Althoughthis may appear a little complicated, theactual operation is simple. There are

Duodyne III.

Accessories are specified as follows :-A-Accumulator or suitable dry -cell battery.B-High-tension dry -cell battery.V-Valve or valves, as required.E-Aerial equipment.T-Telephones.S-Loud-speaker.

two main tuning dials to be adjusted anda reaction or volume -control knob, apartfrom the two filament rheostat knobs.The standard set is contained in an open -fronted cabinet, but an enclosed cabinet,with folding doors, can be supplied ifdesired. Any standard plug-in coils maybe used with the set, and coils to coverthe 250 -500 -metre wavelengths are sup-plied as part of the standard equipment.

Price ,4-tRef. W.M.322

COSMOS. Metro -Vick Supplies,Ltd., 155, Charing Cross Road,W.C.2.

D -2L17. This very serviceable set,arranged in decidedly novel form, incor-

Cosmos Three -velvet.

porates an efficient straightforward cir-cuit, capable of giving satisfactory recep-tion at distances up to 3o-35 miles from amain station and too -15o miles from5XX. Special steps have been taken toensure purity of reproduction rather thanmere volume, whilst the questions ofartistic appearance and general economyin operation have also received attention.There are in all four controls, but twoonly of these are adjusted in normal opera-tion, apart from the vernier adjustmentprovided in connection with the maintuning dial. Interchangeable coil unitsare available and the unit for the normalbroadcast wavelengths may readily be re-placed by one for the 1,300-3,000 metrerange. The complete set may be en-closed beneath a domed cover, which,having a fiat top, forms a suitable standfor the loud -speaker.

PriceAll -in price (ABVES) A714-14--9.

Ref. W.M.326

350

FELLOPHONE SUPER - THREEFellows Magneto Co., Ltd., Cumber-land Avenue, Park Royal, N.W.10.HF-D-LF. A straightforward three -valve set mounted in well -finished slopingmahogany cabinet with ebonite frontpanel carrying all controls, terminals andvalves. Separate filament rheostat knobsare provided for each valve, the remain-ing controls comprising two tuning dials(for the aerial and high -frequency circuitsrespectively) and reaction -control knob.The complete arrangement forms a fairlysensitive and selective receiver, claimed, togive satisfactory loud -speaker receptionat 3o to .40 miles from a main station andcorrespondingly greater distance fromDaventry. As ,supplied, the set can betuned- to all :triormal broadcast, wave-lengths, the long -wave stations (Daventry,Radiola) being brought in by the additionof suitable Fellows loading coils.

Price' .7-.12-o.All -in price (ABVET)

Ref. W.M.327

B.S.A. B.S.A. Radio, Ltd., SmallHeath, Birmingham.D-2LF. In general appearance some-what resembling the two -valve setalready described and illustrated, thisreceiver includes an additional stage oflow -frequency amplification, and isrecommended for use at distances up toSo miles from a main broadcastingstation. Under these conditions, andwith a standard iooft. aerial, satisfactoryloud -speaker volume and good reproduc-tion will be obtained. The tuningarrangement is similar to that used inthe two -valve set, but an improvedvolume control is provided. All batteryleads are combined in one multiple cable,which is attached to the set, the freeends being clearly labelled for connectionto batteries. Once the tuning is set amaster switch controls the operation ofthe set.

Price £15-7-6.All -in price (ABV) £21-17-6.

Ref. W.1\1.329

CARPAX FAMILY. Carpax Co.,Ltd., 312, Deansgate, Manchester.D-2LF. This three -valve family cabinetset is specially designed for clear loud-speaker reception from the nearest broad-casting station with the utmost simplicityin operation. Apart from the three fila-ment rheostats, the controls comprise onemain tuning dial and a reaction dial. Thestandard set is enclosed in a black, pebble-

Carpax Family Three-valver.

grained cabinet, but it can also be ob-tained in a mahogany cabinet of similarshape or in a totally -enclosed mahoganycabinet with folding doors in front andbattery compartment below. All valves,coils, etc., are enclosed but accessiblethrough the hinged lid. Coils for the250-500 metre wavelengths are suppliedwith the set.

Price 4:9 -to -o.All -in price (ABVT)Prices for special cabinet work arc ob-

tainable on application to the makers.Ref. W.M.32o

Simplon Autodyne

SIMPLON AUTODYNE III. DargueBros., Ltd., Simplon Works, SouthStreet, Halifax.

D -21..F. Intended as a family three -valve set for clear loud -speaker receptionof broadcast programmes, this set com-bines handsome external appearance withexcellence of design and ease of operation.By means of a device termed an " auto-matic reaction governor " (the dial andpointer of which will be seen in the lowerleft-hand of the accompanying illustra-tion), manipulation of the vernier knobbeneath the main tuning dial simul-taneously varies the reaction effect andmaintains same at the best value whateverthe wavelength to which the set is tuned.The utility of this device is twofold. Itreduces the tuning to one -dial operationand, whilst maintaining adequate sensi-tivity; it prevents accidental self -oscilla-tion. Jacks are provided for the insertionof loud -speaker or telephone plugs, andthe filament current to the valves is con-trolled by means of two rheostats, theknobs of which are also clearly shown inthe illustration.

Price .4.12-15-o.All -in price (ABVET and S)

Ref. W. M .323

MELLOWTONE. Midland Radio-telephone Manuf'rs., Ltd., BrettellLane Works, Stourbridge.

Mellowtone Three-valver.

D-2 I.F. The illustration representsthis set in box form, but, if desired, itmay also be obtained in de -luxe cabinet.Simplicity and neatness of appearance,ease of operation and good quality repro-duction have been the main points inview in the design of this receiver. Tun-ing is effected by means of one dial twith vernier knob (above the main dial)for final adjustment. Additional ccn-trols are provided for reaction or volumeand for switching off the last valve whensatisfactory volume is obtained without it,whilst a special feature is the provision ofa patented tone -control, by means ofwhich the most pleasing effects can beobtained from different kinds of perform-ance, that is, soprano song, piano solo,military band. The loud -speaker rangeunder normal conditions is claimed to be50-8o miles from a main station and up10 200 miles from 5XX.

Price £16-17-6.All -in price (A BVS) -C28-17-6.

Ref. W.141.312

SIMPLON CABINET AUTODYNEIII. Dargue Bros., Ltd., SimplonWorks, South Street, Halifax.D -21.F. This set comprises the panel,components and circuit arrangement of

Simplon Cabinet Autodyne III.

the table model, mounted complete in ahandsome floor cabinet of best mahogany,substantially made and provided withlifting top and folding doors. Below thereceiving set ample space is available forthe stowage of batteries and other acces-sories. The whole forms quite a neatpiece of furniture, the only external wiresnecessary being the aerial and earth leadsand, when in actual use, the loud -Speakerconnection from the jack on the panel tothe loud -speaker itself, which may con-veniently stand on top of the cabinet.

Price Z18-13-6.All -in price (ABVET and S)

Ref. W.M.324

Wireless Magazine. Mvemben 19261

FOUR -VALVE SETS

ALTHOUGH several combinations ofvalves are possible in a four -valve

set, experience and popular demand haveresulted in one particular type beingmade almost exclusively.

This is a set comprising one high -fre-quency amplifying valve, detector valveand two low -frequency amplifying valves,and usually provided with some form ofswitching arrangement so that the lastvalve may be cut out of circuit whenadequate volume is obtainable upon threevalves.

For the user who desires a selection ofprogrammes from British and Contin-ental stations at good loud -speakerstrength, with occasional full-strengthdance or outdoor music from the localstation or Daventry, this type of four -valve set is thoroughly recommended.Its operation does not call for any specialskill as the controls usually do not exceedtwo dials (for tuning purposes) and someform of volume adjustment.

If used in conjunction with a reason-ably, good aerial -earth system, good loud-speaker volume may readily be obtainedat distances up to too -15o miles from amain station and about 30o miles fromDaventry.

R.I. Radio Instruments, Ltd., 12,Hyde Street, New Oxford Street,W.C.1. -

HE-D-2LE. A particularly neat andefficient cabinet receiver designed tocover the complete range of broadcastwavelengths (actually covering 300-4,000metres) without the use of any inter-changeable coils, and to afford goodquality loud -speaker reception from bothlocal and distant stations. All controlsare carried upon a vertical panel, andcomprise two main tuning, dials, wave-length -range selector, reaction or volumecontrol, and two filament control knobs.The double doors of the cabinet affordaccess to the controls and adequate pro-tection when closed. The base of thecabinet provides accommodation for bat-teries. All terminals are at the back, andvalves, etc., are accessible through ahinged door, also in the back of cabi-net. Within a few miles of a mainstation satisfactory results may be ob-tained upon a small indoor or frameaerial

R.I. Four -valve Set.

If you want further particulars of any of these sets send a postcard to US and save yourself trouble

351

Wireless Magazine, November: 1926

Guide to the Best Valve Sets (Continued)

Price.24-0-o.All -in price (ABVET) Z30-10-3.

Ref. W.NI.4o7

Fellophone Four -valve Cabinet Set.

FELLOPHONE CABINET. FellowsMagneto Co., Ltd., CumberlandAvenue, Park Royal, N.W.10.IIF-D-2LF. This set comprises twowell -finished cabinets, each with foldingdoors, the upper one containing a com-plete receiving set with high -frequencyand detector valves, and the lower one, atwo -valve resistance -coupled amplifier, thewhole forming a compact and all -enclosedfour -valve receiver. The arrangement isselective, easy to operate, and enablesgood quality loud -speaker reproductionto be obtained from most Britishand several Continental broadcastingstations. As supplied, the set coversthe normal broadcast wavelengths but,by the use of additional Fellows plug-in coils, the stations using long waves canbe tuned -in. Apart from the filamentrheostats of the amplifier and a switchto cut out the last valve when not re-quired, the controls are identical withthose of the Fellophone two -valve cabinetset, namely, aerial tuning, H.F. tuningand reaction adjustment.

Price .4.14 -yo -o.All -in price (ABVT) £17-10-0.

Ref. W.M.425

EDISWAN LONG-RANGE. EdisonSwan Electric Co., Ltd., 123/5,Queen Victoria Street, E.C.4.

Ediswan Long-range Four-valver.

Accessories are specified as follows :-A-Acct.= u la to r or suitable dry -cell battery.B-High-tension dry -cell battery.V-Valve or valves, as required.E-Aerial equipment.T-Telephones.S-Loud-speaker.

HF*-D-2LF. This receiver is con-tained in a well -finished cabinet providedwith double doors so that, when not inuse, the control panel may be completelyprotected. The circuit employed is of thedual or reflex type, the first valve function.ing as both H.F. and L.F. amplifier, sothat, with the economy of four valves,results obtained are comparable withthose of a five -valve set. The set is de-signed to operate a loud -speaker on dis-tant stations and enables most Britishand many Continental stations to bereceived at satisfactory strength. Opera-tion is a comparatively simple matter,the normal adjustments comprising twomain tuning dials (aerial and high -frequency respectively) and a reaction -condenser dial. A separate filament rheo-stat is provided for each valve, also on -offand change -over switches. The tuninginductances are in the form of range -blocks, the standard blocks (supplied witheach set) covering 300-500 metres. Addi-tional range -blocks are obtainable whichenable a total wavelength range of too -4,00o metres to be covered.

Price 4 -29 -o -o.All -in price (ABVET)

Ref. W. M. 423

B.R.C. British Radio Corporation,Ltd., Weybridge, Surrey.HF-D-zLF. A substantially -built andwell -finished four -valve set, all enclosed inwalnut cabinet with provision for stowageof high-tension batteries in the base. Thevertical ebonite panel carries all controlsand terminals for loud -speaker or tele-phone leads. Other terminals (for L.T.battery, aerial and earth) are out ofsight at back of cabinet. Operation ofthe set is extremely simple, tuning beingeffected by means of the two main dialsin conjunction with a special wave-length -range selector switch, whilst afurther knob controls the reaction effect.A wavelength range of 200 to 2,000 metresis obtainable without the use of any addi-tional coils, etc. Used with a reasonablyefficient aerial -earth system, satisfactoryloud -speaker volume and good quality re-production are obtainable from mostBritish and several Continental broadcast-ing stations.

Price £21-15-oAll -in price (ABVES) £3o -o -o.

Ref. W.M.42o

EDISWAN JACOBEAN RADIO-PHONE. Edison Swan Electric Co.,Ltd., 123/5, Queen Victoria Street,E.C.4.HF*-D-2I.F. A magnificent cabinetset in Jacobean oak, complete with loud-speaker (normally concealed behind thelouvres of the removable front panel) and

352

providing ample storage for all batteries,and sundries. The upper part of the cabi-net contains the receiving set, whichincorporates the four -valve five -stage cir-cuit of the standard long-rangecabinet set. Immediately beneaththe set is an accessory drawer con-taining telephones for tuning pur-poses, a switch on the set effecting thechange -over to loud -speaker when tuningis completed. The loud -speaker is a

Televox model (listed at 4-5-5-o).All -in price (ABVET and S)The upper part of the cabinet, including

the receiving set, is also obtainable separ-ately, if desired. Price £36-4-41

Ref. W. M .424

Ediswan Jacobean Four.valver.

GECOPHONE CABINET DE-LUXE. General Electric Co., Ltd.,Magnet House, Kingsway, W.C.2.HF-D-2LF. This further model,which incorporates the general circuitarrangements of the previously describedfour -valve sets, is intended to providesatisfactory loud -speaker reception at dis-tances up to to miles from a broadcastingstation, employing only a frame aerial.With the orthodox outdoor aerial, of aver-age efficiency, the loud -speaker range is150-25o miles. The cabinet work is ofhighly finished mahogany with frettedfront to the loud -speaker compartment.The receiving set itself is fitted in theupper portion of the cabinet and enclosedby a hinged cover, whilst in the lowerpart space is provided for stowage of allbatteries and the four pairs of telephonesincluded with the equipment. A Geco-phone loud -speaker is also supplied, andensures adequate volume together withgood quality reproduction. Power ampli-fication is provided for in the two low -frequency stages, and one or both of thepower valves can be cut out of circuit bymeans of a rotary switch. Overall

dimensions : height 4 ft., width 3o in.,depth 21 in.

All -in price (AB VS and 4 phonesZ85 -o -o. Ref. W.M.4t8

CARPAX. Carpax Co., Ltd., 312,Deansgate, Manchester.HF-D-2LF. A well -arranged set incompletely enclosed cabinet, which may behad in black pebble -grain finish or inpolished mahogany. All batteries may bestowed in the base of the cabinet, wherethey are easily accessible from the front.Additional selectivity is gained by the useof a separate and loosely -coupled aerialcircuit and it is claimed that the sensi-tivity and amplification obtainable enablepractically every B.B.C. station andmany Continental stations to be received,even when the local station is not at anygreat distance. The receiver assembly iscontained in the upper portion of the cabi-net, behind a vertical ebonite panel carry-ing the controls, which comprise twomain tuning dials and filament rheostats.

PriceAll -in price (ABVT)

Ref. W.M.421

Carpax Four-valver.

SIMPLON. Dargue Brothers, Ltd.,Simplon Works, Halifax.HF-D-2LF. This four -valve set incor-porates a straightforward circuit arrange-ment, with plug-in coils (aerial, high -frequency and reaction), the completeassembly being fitted into a particularlyhandsome floor -type cabinet of selectedmahogany. The receiver panel ofpolished ebonite is set at a slight slopeto facilitate manipulation of controls, andcarries all valves, coils, tuning dials (twoin number) and terminals. Other essen-tial components are mounted beneath thepanel. In the lower part of the cabinetand enclosed by the double doors, space isprovided for stowage of all batteries andsundries, whilst, when not in use, thepanel, valves, etc., are completely protec-ted by the hinged box -lid. The set is de.signed to give good quality loud -speakerreception of most British and severalContinental stations on the normal broad-cast wavelengths. Reception from thelong -wave stations can be obtained bysubstituting additional plug-in coils.

Price Z.25 -0-o.

Simplon Four -valve Set.

All -in price (ABVET and S)Ref. W.M.422

FIVE -VALVE SETS

THIS type of receiving set almost in-variably consists of two high -fre-

quency amplifying valves (ensuringadequate range and a de-tector valve and two low -frequencyamplifying valves (ensuring satisfactoryloudspeaker volume even when receiv-ing from distant stations).

The modern tendency is towards sim-plification in control without unduesacrifice of efficiency and, although somefive -valve sets require a little care andskill in tuning, many are operated quiteas simply as a three -valve set.

The advantage over a four -valve re-ceiver is that the additional H.F. valveenables long-range reception to be ob-tained without excessively critical adjust-ment of the controls, whilst the extraselectivity which it automatically intro-duces minimises interference fromundesired stations.

Given favourable atmospheric and

A COMPLETE INDEXAPPEARS ON PAGE 355

geographical conditions, together with anefficient aerial -earth system, a well -designed and carefully operated five -valveset will bring in, at reasonably good loud-speaker strength, transmissions of sta-tions at great distances.

Wireress Magazine, Novembel7/926

Even with a moderate aerial thereshould be no difficulty in receiving allBritish and many Continental stations atgood loud -speaker volume.

COSMOS. Metro -Vick Supplies,Ltd., 145, Charing Cross Road,S.W.1.

HF*-D-3LF. Designed to give thebest possible reproduction of broadcastspeech and music, together with a satis-factory distance range and selectivity,this receiver incorporates a special circuitarrangement which, in practice, provesvery effective. The first valve acts in adual capacity as high- and low -frequencyamplifier, the three L.F. valves followingthe detector being operated on the resist-ance -capacity method, well known to givegreat freedom from distortion. Thestandard table set is contained in a well -finished hardwood case with hinged box -type lid. A polished panel carries all con-trols, terminals and switches, the fivevalves being sunk into sockets in thepanel. The controls comprise two tuningadjustments, reaction control, filamentrheostats and on -off switch. By meansof easily interchanged coil -boxes a totalwavelength range of 18o to 3,000 metrescan be covered.

Price £22-5-o.All -in price (ABVET)

Ref. W.M.5o1

Cosmos Five-valver.

ETHOPHONE GRAND. BurndeptWireless, Ltd., Aldine House, Bed-ford Street, W.C.2.2HF-D-2LF. This is a five -valveuniversal receiving set provided withconvenient and efficient switchingarrangements, so that any desired com-bination of valves may be used, whilstthe actual operation of the set may bemade quite simple, or can offer every pos-sible adjustment required by a keenexperimenter. With the first two valvesin use, great amplification is obtained onwavelengths from too to 5,000 metres.By omitting these two valves and chang-ing the plug-in coils the wavelength.

If you want further particulars of any of these sets send a postcard to US and save yourself trouble

353

Wireless Magazine,Novemben1926

Guide to the Best Valve Sets (Continued)

range can be extended to 25,000 metres,if desired. The cabinet is of solidmahogany, inlaid, and measures 35 in.long by 16 in. by 15 in. Full instruc-tions for operation are given in a bookletsupplied with the set.

Price (including valves) .4:78--2-6.All -in price (ABVET and S)

Ref. W.M.5ot

COSMOS LOUD -SPEAKER SET.Metro -Vick Supplies, Ltd., 155,Charing Cross Road, S.W.1.HF*-D-31.17. This represents a furtherdevelopment in which the standard panel

Cosmos Five -valve Set

and assembly are fitted into a seat floor -cabinet, ,together with self-contained loud-speaker. Various types of cabinet workare obtainable varying from a plain, butgood-looking, mahogany cabinet to highlyornate models in- Jacobean and Georgianstyle. The accompanying illustrationshows the simple mahogany cabinet.

Price £46 0 0,All -in price (ABVT and buiit-in loud-

speaker). _ Ref. W.M.5o3

FELLOPHONE SUPER - FIVE.Fellows Magneto Co., Ltd., Cumber-land Avenue, Park Royal, N.W.10.HF-D-3LF. A straightforward andeasily operated five -valve set mounted ina well -finished cabinet provided withglass -panel double doors which afford pro-tection to the main panel, controls, etc.,when the set is not actually in use. Thedegree of sensitivity, together with theample power provided by the three low -frequency valves; should enable excellentloud -speaker reception of all British andmany Continental stations to be obtainedwithout difficulty or especial skill inmaking the necessary adjustments. A re-action control is fitted, which improvesboth sensitivity and selectivity. Thenumber of valves actually in use may bevaried by means of plugs and jacks.Additional cons for reception from 5XX

Accessories are specified as follows:-A-Accumulator or suitable dry-cdl battery.B --High-tension dry -cell ba'ttery.II-Valv?, or valves, as requirod.E-Acrial equipm:ntT-Telephones.S-Loud-speaker.

or other long -wave stations are suppliedwith the set.

Price -Z2 I-0-0.All -in price .4.24. -o -o.

Ref. W.M.5o4

FELLOPHONE CABINET - FIVE.Fellows Magneto Co., Ltd., Cumber-land Avenue, Park Royal, N.W.10.HF-D-3LF. This set is fitted into afine Jacobean oak cabinet or bureau, withloud -speaker incorporated and operatingthrough a circular aperture at the top ofthe cabinet. The control panel is con-veniently situated and is protected by aglazed door, whilst, in the lower part ofthe cabinet, space is available for stowageor all batteries and sundry accessories.

All -in price (ABVET and built-in loud-speaker) Z50 -o -o.

Ref. W.M.5o5

Fellophone Cabinet Five-vaiver.

COSMOS UNIVERSAL. Metro -Vick Supplies, Ltd., 145, CharingCross Road, S.W.1.HF*-D-3LF. A handsome cabinet re-ceiver, completely self-contained except foraerial -earth connections and loud -speaker.The panel and circuit arrangertients areidentical with the standard table modeland are fitted to a substantially built andwell -finished floor cabinet, having amplespace available for stowage of all bat-teries, and obtainable in either mahoganyor Jacobean oak, as desired.

Price (oak) ,4728 -lo -o.All -in price (ABVET) (oak) Z.37-12-6.With mahogany cabinet these prices are

increased by -2-.13-o.Ref. W.M.5o2

354

Cosmos Universal Five-valver.

PORTABLE RECEIVINGSETS

IN this section have been included alltypes of sets with real claims to

portability, whether completely self-contained (that is, with batteries, frame -aerial and loud -speaker all fitted into onecase), or intended for use with a small,temporary outdoor aerial and/or separ-ate and external loud -speaker.

The degree of portability desired byusers or prospective users, the circum-stances in which sets are to be used, andthe class of results desired, vary overwide limits, but, for the purpose of thisguide, only sets which may be carriedcomplete, including all valves andbatteries-even though not actuallyassembled as one unit-properly pro-tected and provided . with convenientmeans for carrying, are considered asportable sets.

The range extends from one-, two-,and three -valve sets to eight -valve super -het sets, so that no general indicationsof range, etc., can be given in this pre-liminary note.

To facilitate reference, however, thefollowing sirliple classification has beenadopted, and the class letter will be foundafter the title of each receiving set.Sets entirely self-contained,

with valves, batteries, frameaerial and loud -speaker ...CLASS A.

Seti complete with valves,batteries and frame aerialbut for use with externalloud -speaker ... ...CLASS B.

Sets complete with valves andbatteries, but for use withtemporary outdoor aerialand external loud -speaker ...CLASS C.

Sets complete with valves andbatteries, but for use withtemporary outdoor aerialand phones only. ... -CLASS D.

UBIQUE IV. Gilfillan Bros., Ltd.,63, High Holborn, W.C.2.HF-D-2LF (Class A). This set,.com-plete as indicated by Class A, is con-tained in a substantial hide case, withcarrying handle, and weighs 21 lb, Pro-vision is made for the use of an externalaerial, also an external loud -speaker ortelephones, if desired. Special featuresare the simple switching arrangementswhich *enable the change -over from thenormal, to long -wave broadcasting, andthe on -off switch which controls thecomplete set and which is auto-matically moved to -the off position whenthe case is closed. At about 20 milesfrom London very satisfactory loud-

speaker results were obtained, the musicbeing clearly audible all over the house.Daventry, some 90 odd miles distant, wasnot quite as loud, but gave satisfactoryroom volume. Altogether an excellentand compact set.

All -in price ..725-0-0.Ref. W.M.6o2

C.A.C. PORTABLE. C.A.C. ValveDistributing Co., Ltd., 10, RangoonStreet, Crutched Friars, E.C.3.HF-D-2LF (Class B). A very compactset, measuring overall 14 in. by 12 in. by8 in., and weighing only 16 lb. It issensitive, having a normal receiving

Wireless Magazine. November:1926 1

range of about 25 miles when used inconjunction with the frame aerial whichis concealed in the hinged front of thecase. Clear reception over much greaterdistances can readily be obtained upontelephones, or upon a loud -speaker if anoutdoor aerial is used. - Provision ismade for connecting the latter, if desired.Valves and batteries, although com-pletely protected, are easily accessible.

Valve filaments are heated by means ofan unspillable accumulator. In operationthe set is very stable and, once adjusted,can be put into or out of action by themovement of a master switch.

Price (AB only) L'22-10-0.Ref. W.M.6o3

INDEX TO DESCRIPTIONS OF THE BEST VALVE SETSIn orderto facilitate reference sets have been indexed under both their tradename, and the manufacturers' name where these differ. Pages 125-133 are

in the September issue and pages 246-255 are in the October issue.

One -valve Sets.Anodion 246C.A.C. 346Carpax 347Fellophone 346Fellows Magneto Co., Ltd. 346Gecophone 125General Electric Co., Ltd. 125Gilfillan Bros., Ltd. 125Gillan 125Marconiphone 125, 246Sterling Anodion 246

One -valve and Crystal Set.B.T.H. 247

Two -valve Sets.A.J.S. 347Anodion 127B.R.C. 348British General 247,B.S.A. 347B.T.H. 126Burndept, Ltd. 126Burne-Jones & Co., Ltd.C.A.C. 126, 249Carpax 249Compactum 348Dargue Bros., Ltd.Edison Bell 347Ediswan 247, 348Ethophone Duplex 126Fellophone 348Fellows Magneto Co., Ltd. 348Gambrell 248, 249Gecophone 126General Electric Co., Ltd. 126General Radio 127Gilfillan Bros., Ltd. 127, 248Gillan 127, 248McMichael, Ltd. 347Magnum 249Marconiphone 127, 248Mellowtone 248Midland Radiotelephone Mnfrs.,

Ltd. 248Polar 127Radio Communication Co., Ltd. 127R.I. 128Simplon 248

249

248

249

Two -valve and Crystal Set.Brownie 348

Three -valve Sets.A.J.S. 349Anodion 130Beard & Fitch, Ltd. 349B.R.C. 349British General 128, 251B.S.A. 35oB.T.H. 129Burndept, Ltd. 128, 25oBurne-Jones & Co., Ltd., 529, 25!Carpax 35oCosmos 35oPeter Curtis, Ltd. 35oDargue Bros., Ltd. 351Duodyne 35oEthophone 128, 25oFellophone 349, 35oFellows Magneto Co., Ltd. 349, 350Gecophone 129General Electric Co., Ltd. 129General Radio 129Gilfillan Bros., Ltd. 129, 251Gillan 129, 251McMichael 35oMagnum 129, 251Marconiphone 13o, 25oMellowtone 351Metro -Vick 35oM -H.. 35oMidland Radiotelephone Mnfrs.,

Ltd. 351Simplon 351Sterling 25oSterling Anodion 130Success 349R.I.25o

Four -valve Sets.Anodion 253B.R.C. 352Burndept Wireless, Ltd. 252, 253,

353Burne-Jones & Co., Ltd. 252C.A.C. 13oCarpax 353Dargue Bros., Ltd. 353

Ediswan 352Ethophone 252, 253Fellophone 352Fellows Magneto Co., Ltd. 352Gecophone 135, 253, 352General Electric Co., Ltd. 131, 253,

352Gilfillan Bros., Ltd. 131Gillan 131Magnum 252Marconiphone 131, 252, 253Mellowtone 253Midland Radiotelephone Mnfrs.,

Ltd. 253Polar 131Radio Communication Co., Ltd. 131R.I. 351Simplon 353Sterling 531, 252, 253

Five -valve Sets.Burndept Wireless, Ltd. 353Cosmos 353, 354Ethophone 353Fellophone 354Fellows Magneto Co., Ltd. 354Metro -Vick Supplies, Ltd. 354

Portable Sets.B.T.H. 254Burne-Jones & Co., Ltd.C.A.C. 355Gilfillan Bros., Ltd. 355Halcyon 254Hart -Collins 132Magnum 133Marconiphone 254Rees -Mace 132Ubique 355

Super -Het. Sets.B.T.H. 133Burndept, Ltd. 255Ethodyne 255Hart -Collins 255

Special Set.Marconiphone 133

133

If you want further particulars of any of these sets send a postcard to US and save yourself trouble

355

Wireless Magazine. Now mben 1926

fTT+1.14777.7../4\7477:17.T..r.r17.1.1..f.rc

GI3 R -The Colonist's Link with Home

F-or when-you listen to Rugby. (GBR) pounding out its threedaily news bulletins, does it ever crossyour mind that those same signalsare simultaneously poking their wayinto the Empire's most distant cor-ners? Do you realise, when you putthe phones on the table and let thembark at you, that the same morse iscoming out-faint but clear-in Mel-bourne, Australia, or in Wellington,New Zealand?

Can you visualise the romance ofthis invisible link that unites the ex-patriated Britisher with London-and all that that name conveys?Even though the broadcast matter isnot always of enthralling interest, itsmere reception acts, for the moment,like a magic carpet that eliminatesspace.

Ten thousand miles-when spokenquickly-may not sound a very longdistance, but it is one over whichwe do not all journey. In the, con-fines of your tight little island acouple of hundred miles is somethingmore than a week -end jaunt to most.

Great SpansYou are, unfortunately, apt to

measure the area of 'a colony by asimilar scale, and to forget that themileage between our Perth andSydney is about the same as thatbetween Liverpool and New York.True, radio has consumed distanceand bridged oceans, but, in order toappreciate its performance, we mustnot forget the length of its spans.

However, ten thousand miles is thelength of the span between my homeand Rugby, and some notes on itsreception, here may be of interest toyou.

Two factors that have to be takeninto consideration are the differencebetween local time and G.M.T. {we

By An Australian Listenerare ten hours ahead of London), andthe fact that static is worse in theselatitudes than in yours. For thesecombined reasons GBR's 8 p.m.transmission (6 a.m. local time)comes through the best even in oursummer-which, of course; is yourwinter.

At that time it is broad daylightand there 'is a minimum of static,

.....v..-N,.....ke,v041,0VAV-0-,""v-W.

YOU HAVE SOME PEOPLEIN THE COLONIES ?

Yes? Then why not send them

a gift of wireless apparatus forChristmas now ?

although it seems anomalous to takedown details of a severe snowstormand, at the same time, to be perspir-ing in pyjamas ! Probably, in theEnglish summer, the midnight periodwill be the best.

There is plenty of kick at this end.At first, with an aerial having anoverall length of only 65ft., and amean height of 3oft., three dull -emitter valvei were employed. Thereceiver took the form of a stage ofhigh -frequency amplification coupledto a detector by means of a tuned -anode circuit and ending with onestage of note magnification. Re-action was employed between the de-tector's plate and the H.F. grid cir-cuit.

This arrangement gave excellentsignals when honeycomb coils of1,5oo turns each were placed in thereaction and anode circuits, whileanother of 1,25o was in' the aerialcircuit. Variable condensers of .00tmicrofarad capacity were used

356

However, there were two sources ofinterference : it was difficult to tune -out Lyons (LY) and Saigon (HZA).In -addition, a harmonic from Bray -brook (3L0), which puts out 5,000watts on a wavelength of 371 metres,and is less than a mile distant,created an absolute blot when inoperation.

However, GBR's signals being sogood, it was decided to abolish thetuned -anode and substitute a straightdetector followed by a stage of L.F.In this instance the time-honouredthree -circuit tuner was employed withthe 1,50o -turn coils in primary andsecondary, and that of 1,25o in thereaction.

The two-valver gives practicallythe same volume as that whereinthree valves were requiied, and, whatis much more important; there is notthe slightest interference from any-where. Certainly -there is a minorundercurrent of LY, but nothingthat need worry the poorest operator.

We do not know just how muchpower Rugby.: -is employing, but,when properly tuned; Lyons' signalsare quite twice, the strength of GBR,and, at -their S p.m: (G..M.T.) timesignals, the FrenchMan simplyrompsin. .

Reciprocation ?

I have mentioned Braybrook (3L0)as a fairly powerful broadcaStingstation which is 'situated in the sub-urbs- of Melbourne. In view of thefact that we occasionally hear your.2L0 on -four- and -five-valve setsthere seems no reason why youshould not be able to reciprocate.

Two' other Australian stations uti-lise' the same power, Sydney (2FC)and Perth (6WF), and work on wave- lengths of. ',too and 1,250 ,metres.respectively. L. 13..

OM.

510DCAST

giUSicofthe

ALTHOUGH the season forwhich we were promised lighter

musical fare has passed, I am gladto note that we are still hearingmany of the light orchestras from thevarious hotels and cinemas. These,in fact, are in many cases the onlyoases in the dreary wastes of inter-minable folk -songs of Elizabethantimes or the syncopated brutalities ofsound termed " jazz "

Miss Lilias Mackinnon.

When we get oppor-tunities for hearingthe best and mostmelodious of worksfrom the highly -trained musicians whomake up these outsideorchestras, we appre-ciate it.

Such artists asEmilio Colombo,Camille Couturier,

Arthur Salis-bury.DeGroot, a n dFrank West-field have allmade themusical accompaniment of a meal (a.a cinema film so important that with-out it neither would be complete.

Mr. Frank Westfield has perhapsthe largest orchestra in any picture

house in London, and thePrince of Wales, Lewisham,

has justly become a musi-cal centre of South Lon-don ; the weekly broad-

casts are more appre,ciated than many of

the wearisome studioconcerts. Mr. West-field claims to havehad hundreds of let-ters of appreciation ofhis work.

Besides the other bandsof the month may bementioned the Kettner

Five and the RomaineFour from the SavoyHotel, this combination

taking the place of the earlierquartet known as the Selma

One of the best of the newrestaurant bands is that from theCafé Verrey, where Mr. ArthurSalisbury leads. Mr. Salisburyalready has a big reputation behindhim; a pupil of Gomez and Melzak,he was just making public progresswhen the war interrupted his career.

His SuccessesAfter three years, on his discharge

from the Army, he became leader ofDe Groot's orchestra at the Picca-dilly; later he left De Groot to take

357

[ Wireless Magazine. November:1926

Miss Winifred Fisher

charge of Verrey's. He hasrecently been heard at theHolborn Empire with his col-leagues, L. Racklin ('cello)and A. Ferraris (piano).

Apart from the militarybands of the famous regi-ments, such as the StringBand of the Royal Artillery,the Grenadiers, andthe Air Force Bands,many of provincialfame have been heard,such as the St. Hilda'sColliery Band, Callen-der's Band, a n dothers. The firstband is attached tothe famous Callen-der's Cable Works and is directed byMr. Tom Morgan, who, being one ofthe best-known cornettists in thecountry, has played with the Cold-stream Guards for six years andtaken part in engagements underEdward German, Sir Edward Elgar,Sir. Landon Ronald, as well as withthe Savoy and Carl Rosa Opera Com-panies.

With Callender's BandSince 1913 Mr. Morgan has been

director of Callender's Band, whichhas broadcast so frequently of late.As an adjudicator, also, Mr. Morganhas won fame throughout this coun-try, Australia, and New Zealand.

Almost all of the provincial sta-tions have been made conspicuous bythe work of respective artists. At

r

Miss EdithBarnett.

Wireless Magazine.November:1926

Miss Marguerite Bamberg.

Birmingham, t h e5IT Orchestra hasbeen led and oftenconducted by Mr.Frank Cantell since

1924. He was, and is still',leader of the popular stationquintet and has made theirwork an outstanding item inthe daily programmes.

Mr. Cantell is a student of the Birmingham and MidlandInstitute and began a professional career at the age of eleven.In addition to his prowess as violinist, he was principal violafor two seasons for the Birmingham City Orchestra.

Mr. Frederick J. Thurston is another of the earliest broad-casters, at Marconi House in 1922. As a clarinettist, he hasplayed with most of the big chamber -music combinations andalso the Royal Opera, Covent Garden. His broadcasting workis connected mainly with chamber music, and he has beenheard frequently this month.

Pianoforte RecitalsThe series cf short pianoforte recitals has again been the

means of introducing some famous artists to the widest possi-ble public. Mention may be made of Miss Lilias Mackinnon,who, apart from her own wide concert -hall experience, hasadded technical training to her art and devised a memorisingmethod which has met with the approval of the greatestpianists in the world, including Myra Hess, Irene Scharrer,Serge Kousevisky and many others. Miss Mackinnon's play-ing is always conspicuous for its clarity and power.

Besides otherpianists maybe mentioned MissEdith Barnett, whomade the composerWeber her especialriedium, and Mr.Rae Robertson,with his fortnightdevoted to theElizabethan music

Mr. Arthur Salisbury.

in the FitzWilliam Virginal Books. Mr. Robert-son is an exponent of the famous Tobias Matthaysystem of playing, which is essentially suitable tothe Virginal music.

Miss Doris WorsleyMiss Doris Worsley is another artist who has

made pianoforte playing her art since the age ofsix. An open competition gave her a year atthe University of Wales, and she won later theCaradoc Scholarship. Taking up concert work,Miss Worsley has given several recitals and iswidely known not only for her instrumental work,but for her clever character studies and child im-personations.

We have had opportunities this month of hear-ing many artists of the younger school, amongstthem Miss Joan Elwes, whose singing of Bacharias has placed her amongst the first rank ofclassical concert singers.

Miss Lilian Cooper is a clever young soprano, apupil of Esta D'Argo, and winner last year of theSoprano and Rose Bowl Competitions at Black-pool. She has broadcast on many occasions,notably in a recital of Grieg Songs.

Miss Winifred Fisher needs little introduction tolisteners, for I think she was one of the earliestartists to broadcast. From the very outset shehas made a point of singing suitable songs witha clarity and beauty of diction that has made herone of the favourite artists in every request pro-gramme.

Mr. Stanley RileyOn the masculine side we have had Mr. Stanley

Riley who, apart from his fine work over the ether,will probably be remembered to listeners for theromance of his engagement and marriage last yearto Miss Joan Strong, of the Wireless Chorus.

Mr. Riley has a great career before him ; alreadyat 25 he is the youngest Assistant Vicar Choral at

Mr. Rex Burchell.

358

Miss Winifred Fairlie.

Mr. Frank Cantell.

Wireless Magazine. Nownthen 6026

Sir Martin Harvey.

St. Paul's Cathedral, as well as bass soloist and leaderof the Wireless Orchestra at 2L0. He has had variedexperience as concert singer and also of stage workunder Dion Titheradge at His Majesty's Theatre. Hiswork over the ether is outstanding.

Mr. Gilbert Bailey is another well-known singer whohas been heard again recently. He has been heard frommany stations, but his recitals at 2L0 and Daventryadded considerable distinction to the ' programmes byreason of his choice of song.

For Lighter FareFor lighter fare we have depended mainly on concert

parties, cabaret shows, and a surplus of syncopatedmusic. Amongst those who are always welcome maybe mentioned Miss Winifred Fairlie and Mr. CharlesHarris, who, if our memory does not fail us, was firstheard over the ether last year with his own concert party,The Londoners.

Helena Millais, John Henry, Vivian Foster, and WillieRouse have also given us of their best.

The talkers predominate in many instances, but thereare a' few whose work is of sufficient interest to beeagerly welcomed-those of Sir William Bragg, Mr.Allen Walker, and Desmond MacCarthy, besides a hostof others.

Up in the North the work of Augustus Beddie isalways welcomed, and his recitals both over the etherand at various halls are always well received. . Pro-bably he is one of the few talkers whose work has beenrecorded for home music and entertainment. Thisautumn he has given some " Portraits of. History " andpoetical extracts.

Herbs and Herb GardensProbably few people realised the fascination of herbs

and a herb garden till they heard the lectures of EleanourSinclair Rohde, the authoress of many charming bookson this subject.

Mr. Moses Baritz is probably t'..e most famous talkerof the B.B.C., as from the very beginning at the Man -

Mr. Stanley Riley.

chester Stationhe started hislectures o noperatic musica n d utilisedthe greatgramophone re-cords to illus-trate hispoints. He hasbroadcast in this way from many other stations, and isone of the greatest authorities on operatic music and themaking of operas that we have in this country.

Taking a broad outlook of the month's music andprogrammes, there is art obvious effort to providecontrast, the result often failing through the lack ofutilising music more suited for the masses than thefew who can better afford to indulge their classicaltastes at the standard concert halls.

The Larger PublicThat there is an audience for this type of work we do

not doubt, but the larger public is that scattered through-out the country, and it is more than doubtful if a Greekplay of. Euripides or -a constant flow of Elizabethan folksong and' the classical works of Bach, Brahms, andBeethoven are of overwhelming interest.

Given alternative programmes of classical and popularmusic, all might yet be well, but at present the manyare still being forced to enjoy items specially to the tasteof the chosen few.

Mr. Moses Baritz

359

Mr. GilbertBailey.

Wireless Magazine, November 1926

Therfoclern,A story of modernscientific gambling-with a wireless set!

THE maids had gone to thecinema, so I opened the door

myself. Twenty years ago such anobject as I now beheld would eitherhave been immersed in the quadfountain or deprived of his trousers ;his hair was greased and parteddown 'the middle, while he worehorn goggles and trousers capaciousenough to accommodate an entireboat's crew of A.B.s.

By this time Julie, my youngerdaughter, was mysteriously at myelbow. " This is Bill, dad ! " sheexplained. I had never heard ofBill ; were they secretly married,or had they met for the first' timelast night ? With the moderndaughter one never knows.

" How d'ye do, Bill ? " I tem-porised. He -wrung my' handeffusively : evidently they weren'tmarried yet. " Have you got thedoings, Bill ? " continued Julie," bring 'em right in."

The modern parent being a nonen-tity in his own house, I meeklyassisted Bill to retrieve from his cara large blue leatherette suitcase,and a small mahogany object whichI mistook for a tea caddy. Abettedby Julie, he took the " doings "into the drawing -room. Roulettecrossed my mind ; also thoughts ofa protest. Bill received rapturousgreetings from the assembly, noneof whom knew him, though all wereexpecting him.

Handling the suitcase delicately,he removed its lid, which he stuckon a small pivot ; peeping overyounger shoulders, I discovered eightvalves on a shelf inside it. Billnext laid on the table a periodicalpreviously unknown to me. Theyoung folk informed me pityinglythat it contained the programmes,call signs, and wavelengths of all theContinental broadcasting stations.

We now settled down to modern

izard

scientific gambling. Each personin turn selected a station from thelist in the paper. Julie then juggledwith the mahogany tea caddy. Itmade no immediate protest, but Iwas given to understand that itemanated waves identical with thoseof the specified station. Bill thenmade magic passes over the blueleatherette suitcase, from the bowelsof which a small horn projected.When the suitcase and tea caddywere adjusted to perfect sympathy,the horn emitted a loud boomingnoise, reminiscent of a ship's sirenin a fog.

When Bill was satisfied, he noddedto Julie-speech was inaudibleagainst the siren. Julie then switchedoff the tea caddy, and the Ruritanianstation should be audible on the loud-speaker. If it was, Bill got a shillingfrom the person who had namedRuritania. If it wasn't, Bill paid ashilling.

I listened in considerable mysti-fication. The odds seemed to beheavily in favour of the bank, andBill collected a number of shillingsby successively tuning -in Rome,Madrid, Munster, Toulouse, Brussels,and several weird places which I vowwere never on the map in my school-days, including Ryvang and Oslo.

If the item being transmittedchanced to be jazz, gambling wassuspended, and the company-alwaysexcluding the elderly master of thehouse-curvetted gaily till the stationfaded or the tune ceased.

Presently a slight fracas arose.Young Harcourt's turn came, and hedemanded some outlandish placecalled Hilversum. Julie set the teacaddy, Bill tuned -in the foghorneffect, Julie switched off the wave -meter, and a deathly silence ensured.It lasted a minute or two and Har-court held out his hand for a shilling.

all did not pay up, which I

360

Lino Cut by William Kermoda.

thought ungracious, as his pocketwas bulging by this time. Hetickled another knob, and the suit-case gave an impression of a some-what anwmic pig being slaughteredat a great distance. This, he alleged,was Hilversum's " carrier wave "-whatever a carrier wave may . be.Hilversum, it was claimed, wasenjoying an interval : if we waiteda few moments, the night would .befilled with Dutch music. We waited.It wasn't.

The company appointed me a sortof amateur Tattersall. I realisedby this time that Bill's reluctance topay up was not avarice, but atechnical conscience. He could notbear the blue suitcase to be defeated.I honoured his motives. "Thatunmelodious noise," I decided firmly," is Hilversum's carrier wave." Har-court paid.

After a few more tangos, fox-trots, and guttural unintelligibilities,the damsel on my right chose Zurichto carry her shilling, and handed methe periodical. I pored over it,realising my gross ignorance ofmodern geography. But near theright-hand bottom corner of the listI identified a certain winner. Themale voice quartette from Zurichconcluded their tremolos, and Billgazed at me expectantly.

" Jonkoping on 265 metres ! "I demanded in accents which triednot to be too triumphant. Therewas a deathly silence. Even Billseemed daunted. I saw at once thatin my senile ignorance I had brokensome unwritten law of the game.I felt as if I had shot a fox, or waswearing a made-up tie.

Murmurs of protest arose faintlyfrom the assembly. " There isn'tsuch a station 1 " and so on. Billstretched out a doubtful hand forthe paper. " It's a relay I " hemurmured in a tone of d ep disgust.

Evidently there is something in-decent about relays ; meditatingflight, I wondered what frightfulfaux pas I had committed.

" Where ? " enquired Joan." Sweden," explained Harcourt, whowas sharing the paper with Bill, " andonly half a kilowatt ! "

I wished the floor would open underme. " Never mind," I intervenedhastily, " I'm not really interestedin Jonkoping, I only thought it hadrather an intriguing sort of name,and I've never heard Swedish spoken.I don't mind at all, honestly I don't.I'll pick another." I snatched theperiodical from the lads, and fumbled," Give me Bournemouth ! "

Howls of execration arose fromthe multitude. Bill, it appeared,was the super wireless product of ascientific century. Bournemouth wasa station which any schoolboy couldpick up on a crystal. It was asif I had asked Fender whether heknew how to bowl a yorker.Muttering something about seeingwhether there were any more syphonsin the pantry, I fled from the room.

G. W.

"'V ^'\e"'"1.,""\eMe^'...0-1,-*N.r."1"'""\e^"\e' 0

TOO MUCHWIRELESS ?

0 "u"se\oe+1...e".."04-"....i\..."...e.%-e-"\"."....e,

SOME people are never tir d ofcomplaining about radio ; but I

think the most original growl comesfrom a gentleman who has heroicallydecided not to touch the earphoneson certain nights because the ubiquityof wireless tempts him away fromother recreations.

One can't help feeling, " Well,why not, if he enjoys listening -in somuch better than his other recrea-tions ? It's not work that'ssuffering."

Still, I think this must be a raregrouse. For one thing, it impliesso much more leisure for listening -inthan most of us get. It also impliesthat the gentleman never stirs fromhome day in, day out, since hementions tea- and dinner -time trans-missions.

Most of us-at any rate, us women-by the time we are through withour work and have allowed for theafternoons and evenings we spendout and entertaining friends, don'tfind we suffer from an overdose ofbroadcasting A. M. M.

83

WirelessMagazine.,%tembir1926

0

PROSPECTING BY WIRELESSN.r".....".e"..e""r"..o"...rWSov"ovs Nov' NseeSrges 0

IT is well known that the presenceof conducting bodies obstructs the

passage of ether waves. The use ofa screening or reflecting network ofwire, placed behind the radiatingsystem of a directional. hea.m trans-mitter, is one illustration of thisaction.

Twisted Wave -frontsWhen an ordinary direction -finding

set is used on board ship or in anaeroplane, it is found that thedirection of the incoming wave -frontis disturbed or twisted out of thetrue by the action of any adjacentmetal funnels, hatch coverings, staywires and the like, and it is necessaryto calibrate and allow for thisquadrantal error, as it is called.

The angle of twist is calculated bya method similar to that employedwhen heeling a ship for magneticdeviation, due to the presence ofiron, upon a ship's compass.

In the course of some recent ex-periments in direction -finding onland, carried out by the Air Ministry,a mysterious but constant error wasfound to occur in the calculatedbearings of certain stations. Varioussuggestions were put forward inexplanation, but no satisfactory solu-tion was found until one ingeniousinvestigator thought of examining the,ground in the vicinity of the wirelesshut.

The clue to the puzzle was thendiscovered in the shape of a segmentof metal pipe -line, which had beenlying buried some feet under thesoil for many years. Its existencehad been totally forgotten until itsucceeded in making its presence feltthrough the medium of wireless.

The same basic idea underlies anew method for locating metal oreswhich has recently been inventedin Australia and tried out on a largescale in New South Wales. The testswere made on the side of a mountainsuspected to contain rich deposits ofore in the neighbourhood of thetown of Hillgrove.

The prospecting apparatus con-sists of a low -power transmitter andreceiver combination, which areplaced in position about coo yardsapart. The transmitting and re-ceiving aerials are in the form of smallframes or helices.

361

After first getting into touch, withboth aerials upright and facing eachother, the frames are gradually de-pressed towards the horizontal posi-tion so that a concentrated beam ofradiatiOn is directed through the partof th 3 mountain -side under in-vestigation.

If no sound is heard, it is evidencethat there is no metallic or con-ducting mass buried in the soilbetween the transmitter and receiver,but if signals are obtained then orehas been located. By noting theangle at which the frame aerialsgive maximum signal strength, thedepth of the reflecting mass ofmetal can be calculated, the lengthof the base -line between the twoinstruments being known.

A somewhat similar idea has beenutilised by a French inventor, M.Langevin, for indicating the depthof water under a ship. Here, how-ever, ultra -acoustic sound vibrationsare directed towards and reflectedback from the sea bottom,. the timeinterval between the moment whenthe sound vibrations are emitted andthe moment when the reflected echoreturns being registered by means ofa thermionic valve.

The valve is initially paralysed bymeans of a high negative charge onthe grid. The depression of a keyused to operate the sound -producershort-circuits a blocking condenserin the grid circuit of the valve, andso removes the bias, whereupon acurrent immediately flows throughan integrating recorder in the platecircuit.

Restoring Original BiasThis current continues to flow

until the reflected echo is receivedupon the grid of a second valve.The corresponding change of platecurrent in the second valve isarranged to restore the original gridbias on the first valve, the platecurrent of which accordingly stops.

The reading of the integratinginstrument then gives a record ofthe interval that has elapsed betweenthe original outgoing sound and theimpact of the echo, and the velocitywith which a sound wave travelsthrough the water being, known, thedepth of sea at any given point canreadily be determined. B. A. R.

Wireless Magazine Voternber 1926

Radio San Sebastian

MOST of the Spanish broadcast-ing stations are very well re-

ceived even by English listeners whouse only the simplest of one -valvesets, and the transmissions of SanSebastian (its call sign is EAJ8) comein with particularly good volume.For this reason additional interest isadded to the photographs that appearon this page.

These photographs have been sentto us specially by the engineer of theSan Sebastian station, Dr. FerminRodrigues. In his letter Dr. Rod-rigues says : " Please be kind enoughto excuse the liberty I take in writ-ting you, and pray forgive me if I

spoil your language, of which, I antsorry no to have a proper know-ledge."

die spur of the moment. Thoughtand research in quotation books -would surely discover others, -equally or more appropriate. -

Like softest music to attending cars.-Shakespeare.

Give us grace to listen well.-Keble.They hear a voice in every wind.-

Gray.Sounds overflow the listener's brain,So sweet, that joy is almost pain.-

Shelley.Or, perhaps best of all, Long -fellow's :--

And the night shall be filled withmusic,

And the cares that infest the day,Shall fold their tents like the Arabs,

And as silently steal away.So much for the wireless set.

And for speakers before the micro-phone, with the B.B.C. bogey ofcensorship always dangled beforethem, who can better this dictum ofBacon's that, " Discretion of speechis more than eloquence "? M.

We assure Dr. Rodrigues that weare glad to have the opportunity ifpublishing these special phOtographsof his station.

The San Sebastian transmitter issituated outside the town on a moun-tain called Monte Igueldo, as can beseen from the leading photograph.The transmitting gear is installed inthe building directly underneath theaerial. The studio itself is in thetown of San Sebastian.

A. Motto for Your Set ?AN apt quotation is always a joy--

hence the prevailing habit ofhaving one beautifully lettered,framed and hung over the hearth, oron the walls as a motto. Why not,then, a motto for the wireless set? It.would have to be found from amongthe classic authorswho never heardof radio and theingenuity requiredto discover some-thing appropriatewould make anamusing littlefamily- or partycompetition.

Here are myown entries for thecontest, made on

Many English listeners are familiar with. SanSebastian, EAJ8. These photographs show theengineer attending to the transmitting gear; onthe left he is adjusting the aerial tuning and abovehe is measuring the wavelength before starting totransmit a programme.

362

Wireless Magazine. Novemben/9261

SOLDERING(vigour 910afw

An Article That Will SaveThe Home Constructor Pain

"OH'I can't be bothered to

solder the connections ! Iknow it's 'supposed to be more ef-fective, but it's such a messy busi-ness ! "

But really soldering and unsolder-ing are no more tedious than twistingand untwisting wires, and need inno circumstances be described as" messy."

Main PointsThe main points to remember

are these :ALWAYS-

Observe strict mechanical cleanli-ness.

Maintain a proper temperature ofthe bit.

Keep the bit in a properly tinned,condition.

NEVER-Allow solder or work to oxidise.Be too lavish with flux.Handle the surfaces to be soldered..sonce they have been preparedfor the operation of soldering.

Most of the foregoing points mayugefully be elaborated a little, whileone at least needs to receive attentionin detail.

By mechanical cleanliness is meantabSende of all matter or conditionsinimical to the success of the opera-tion of soldering, for example, tarnishor oxidisation, greage, sooty dePosits,etc. The presence of such matterin even minute quantities is sufficient -to cause partial or complete failure insoldering, so that every surface tobe worked should first of all becleaned either with emery cloth or asmooth file.

It is unwise to assume that alreadytinned surfaces, such as those oftinned wire, tags, etc., do not re-quire any cleaning. The cleaningin these cases may, however, be

confined to rubbing with a cottonrag on which a little flux has beensmeared, though if they are badlytarnished the emery cloth should bebrought into use.

Certain means sometimes used forheating the bit are totally unsuitablefor the purpose. A coal fire is one.Gas is not good, not only becauseit contains too many sooty impuri-ties and oxidising agents, but alsobecause its heating qualities are toogreat to be readily regulated for thepurpose in hand.

The most suitable and convenientagent to use is undoubtedly a methy-lated -spirit flame, in which the bitcan usually be left for quite a con-siderable period without raising itstemperature sufficiently to causeoxidisation of the tinned surface.Small spirit lamps,especially designedfor soldering work, may be purchasedat small cost. It is advisable tochoose a make which includes ahinged support for the bit.

The point relative to keeping thebit in a properly tinned conditionis of such importance that the pro-cess of tinning will be briefly des-cribed and hints added as to theproper maintenance of that condi-tion. *

"Tinning" the Bit .

Tinning is the process by which anysurface (not Only that of the bit) iscovered with a coating of brightsolder. To do this with a new bit,it or rather the copper portion (thebolt), should be cleaned with emerycloth and the bit brought to theproper temperature in the spiritflame. This is- the case when theflame becomes tinged with a greencolour.*

Here a word of warning. Neverallow the tinned portion of the bitor that portion about to be tinned

363

to come into direct contact with theheating -flame, which. should only bealloWed -to play: upon. that part ofthe -bit where the bolt is rivetted tothe: shank. Remove, the bit fromthe. flame; dip, the end of the .stickof sober into flux, and with it lightlytouch each of the bevelled 'surfaces.

The solder will probably not runevenly, but will collect in " blobs,"so in order to spread it satisfactorilyover the entire surface the - bitshould be wiped while still hot on acotton rag on which a small quantityof flux has been smeared. Theoperation is then finished, and it willbe seen that the business portionof the bit is completely covered witha bright coating of " tin." -

Keeping the Bit "Tinned"This is the condition of the bit

which it is necessary to maintain ifquick, clean, and firm joints are tobe effected. Should by any chancethe tinned surface become dull(that is oxidised); or otherwisemechanically dirty, the bit should beheated and wiped thoroughly on thecotton rag. already referred to.

In some cases'. where the bit' hasgot into a particularly bad condition,it may be necessary to have redonrselto a file tb remove the entire ekisiingsurface. The bit must then be re -tinned in the manner described. The rag aheadY twice mentioned

reqUire-s a short note to emphasisethe necessity of its :consisting ofvegetable, fibre, such as cotton, andnot of animal fibre, such as wool,Which, owing t,o the quantity Of

grease and other carbon it contains,soon ruins the surface of the bit forsoldering purposes.

The remaining points can- be dealtWith in a few words. Oxidisation,as can' readily he inferred froni whathas already been written, is the Main

WirelessMagazine. November:1926

Soldering Without Groans I (Continued)

enemy of successful soldering. Thisundesirable condition is usually theresult of overheating, although italso follows from exposure ,to theatmosphere for any length of timeand it is mainly to counter its effectsthat flux is. used.

That is no excuse, however, foran improper use of this invaluablematerial. It should be rememberedas an axiom that the slightest touchof flux properly applied in the rightplace is Of far more value than whole-sale and indiscriminate smears.

'Ware Burns !The main reason for not handling

surfaces to be soldered has alreadybeen intimated, namely, because theminute quantity of grease so de-posited is sufficient to prevent asuccessful joint. Apart from thatreason, however, it is wise to handle

material to,be Worked only with a pairof pliers, because the heat from thebit. travels much more rapidly andmuch further than one might imagine,arid one is apt to receive a nasty -burn.if care is not taken in this respect.

A few general hints in conclusionAlways have tools and materials.ready to hand. Much valuable timeis lost otherwise, not to speak of thevexation caused by having to reheata cooled bit ata critical moment justbecause it has been necessary tospend a few moments looking forsome gadget or other.

It is a good plan to coil the stickof solder so that it may lie conven-iently on the bench or table in sucha position that in order to replenishthe supply of molten solder on thetip o' the bit, all that is necessaryis to touch it lightly with the latterimplement.

Square -tinned wire has many ad-vantages over the round variety as faras ease of soldering is concerned.;It is important to remember, how-

ever, that in order to effect reallysound joints ,at least three adjacentsurfaces .of square wire should becleaned preparatory to applying'the. solder so that the latter mayflow readily all round the actualsurface to be joined.

UnsolderingLastly, to unsolder, all that is re-

quired to separate the joints is a hotbit and a pair of pliers. The writerguarantees that with a little practicea dozen soldered joints may be un-stuck in as many seconds. Comparethis rapidity of work with the tediumof unscrewing nuts and untwistingwires !

E. L. M.

1."Ni..^.1,..'ve,'\e."W\e^1.e-W1e ^'1.r^'\e^'N'^'VW\e^'40e,*.V.^.\e,"*V^'VA t

"SSSH!4 4 Adventuresat a Listening-rn Party, 10e1..edVeAned\nerAwei\."..r"..v.4.0".-e".04e"..."..0"..e r".."..e"....ed\weeN.A..edlneo\nr

"C ANyou come on Thursday

evening to listen -in ? Mary hasjust got her wireless up, and sheknows how very musical you are,and that you have never liStened-inyet." '

" So many thanks ! " you say ;and you. hurry off- on Thursdayevening, . thinking " Never mindthe weather.: there's beautiful musicwhen I get -there."

And so there was ! Mary sat onone side of the fire, and her fatheron the other, and I was given a placein, the - .noiddle. - The only threephones were produced, and we, fixedthem on our three happy heads.Mother got out some sewing. Hildasat and read a book.

In the middle of a lovely song,mother tip -toed to the back of myhead and whispered : " Are yourphones on quite right ? " I said :" Oh quite, tha--" " Sssh ! "she breathed, giving my phones ajerk, and I missed- that climax inthe song !.

During the next lovely item, myleft eye saw mother waving violentlyto Hilda. The girl looked up fromher book at last and said : " What,Mummy ? " " Sssh 1"

Then much pointing to the fire andcoal scuttle. Hilda gets up andpicks up the tongs. (" Sssh ! ") Shethrows a lump of coal on., (" Sssh ! ")She goes, back to her book, andunfortunately drops it. (" Sssh ! ")

We are, getting on nicely now, whenmother extends her hand towards theyoung reader and .waves it up and

UP AGAINST -AKNOTTY PROBLEM?

Let us help, you. Send your ques-tions (together with the coupon oncover iii and a stamped addressedenvelope) to The Editor, WIRELESSMAGAZINE, La Belle Sauvage,E.C.4, and we will let you hatea reply in a few posts.

down, then .waggles two fingerstogether in the manner of -cuttingwith scissors and points towardsupstairs. Hilda says : " Do yotiwant your scissors, Mummy ?(" Sssh ! ") Hilda opens the door(" Sssh ! ") and finally gets thescissors. Returning, she closes thedoor again (" Sssh I ").

Later, during an interesting item,364

mother tip -toes, with Much silentjerking of the body, to Mary, andwhispers. Mary says: " Oh, Mother!"" Sssh-sgh-ssh "

Mary moves to another seat,accompanied by many " SssIt's ! "and mother brings in the kettle andputs it on the fire for making hotdrink. Dad says : " What, al-ready ?" " Sssh-sssh-sssh-sssh-sssh-sssh ! " 'Another item spoilt I

Never mind ! Now there's a lovelybaritone song, and you've forgottenall the antics witnessed before.

What a fine voice you arethinking ; and his compass isreally most " Do you prefercocoa or coffee ? " is whispered intoyour ear: You almost jump, for youhad not seen or felt mother comingthis time.

You'd like to answer that you'dprefer. music, but politeness has tobe considered ; so you . lose thepoint in the song, and say : " Oh Icocoa, thank " (" Sssh I")

At the end of the evening mothersays : " Come again next Thursday,won't you ? " You are driven reluc-tantly to say : " I'm so sorry, butI am full up that evening."(" Sssh I ") A. M. C.

IMMO = =dm, =: 1=1 1111 111111 = =NM =

Wireless Magazine, Atntinber 1926

mni .11=. =

DECORATING YOUR

I WIRELESS CABINETSBy

S.N.Sedgwick.

NOBODY can say that wirelesscabinets are particularly artistic

or beautiful. Generally speaking,they may be described as plainand useful, but certainly not orna-mental. Every reader is familiz rwith the usual shapes and designs t)be found in every wireless shop- -plain rectangular boxes or desk -shaped cases of oak ormahogany (chiefly imita-tion) devoid, as a rule, ofany sort of carving ordecoration.

No doubt, at this stage ofwireless history, this is allthat we can expect; butthe time is coming when Wemay fairly look for some-thing rather more decora-tive and beautiful in cut -ward appearance.

It is a commonplace tosay that every person whogets bitten by the new de-lights of listening -in looksupon wireless as the mostwonderful invention of thecentury.

"Little short of a mira-cle," is a frequent descrip-tion of it and no one willdeny that there is some-thing akin to the marvellousin the picture of, shall wesay, a working man in asmall cottage in an out-of-the-way village, sitting downin the evening to manipu-late a power which bringshim into touch with all theworld.

Just because that is so, it may wellfollow that when the artist and thecraftsman apply their faculties to thedecoratiOn and adornment of wirelesscabinets they will want to let theirimaginations play, and to make theircarvings . or paintings enshrine thisthought.

Designs byMolly Dowler

One might almost say that wirelessis too fine and magical a thing to beexpressed outwardly in plain woodboxes and ugly sloping cubes. Thejars and other receptacles in whichthe wizards of the Arabian Nightskept their magic charms were madeto match.

Our fathers took care that the same

Fig. 1.-A " Waves " Cabinc t Decoration.

principle was applied to the instru-ments with which they viewed thestars ; and even in prosaic matters,such as printing, their old pressesstood on fine iron dragons, orleviathans that were more or lessemblematical.

There is room, then, for the artist365

= IMMO =

1

and the designer in the wireless worldof to -day.

Here are two designs which havebeen used in the making of somesimple wireless cabinets, and alsothe photograph of a crystal setcompleted for a lady's drawing -room.

In them the artist has introducedthat touch of fantasy which is

referred to above, and eachdesign contains some wire-less " allegory," not with-out a hint of humour.

In Fig. 1, the mainthought is " waves," ofcourse. ---".the swelling of thevoiceful sea." The twolower panels form the doorsand, when open, the backof the right-hand door hearsa carved inscription :-Certain stars shoot madly

from their spheresTo hear the sea -maid's music.

The other door carrieshaucer's words, which

illustrate the bo Aom de-sign :-Oh, it was wonder like to

beeSong of meremaidens of the

seeThat for hir singen is so

clere.

For Fig. 2, the main ideais " Ariel "-a whimsicalpun, not without poetry init, as we think of Prospero'sfairy servant who " drinksthe air and returns,. Or e'eryour pulse twice beat." Butthis is Ariel set free to

listen t o the horns of elf -land. Inthis cabinet the ebonite panel isbehind the folding doors.

The heading photograph illus-trates a neatly designed crystal -set.In this set nothing is visible exceptfour terminals, which are nt theback of the cabinet. The design,

Wireless Magazine, Novemben1926 I

Decorating Your Wireless Cabinets (Continued)

in this case, explains itself ; the coloured woods-padouk, wIntewood,quotation

Music on the spirit liesLike tired lids on tired eyes.

reminds us of those fallasleep with earphones on,though the artist haSdrawn a " loud -speaker,"through which the dis-tant Pierrot's voice haslulled the listener to slum-ber.

Direct CarvingThere are several ways

by which .these or otherdesigns can be produced.Direct carving on thewood suits the second de-sign particularly well, butthose who can use a fret -saw, can produce the de-sign by fretwork overlays,

silverwood, chestnut, which can beThere are also marqUetry inlay

transfers which can be used inartistic hands to transform a plainbox into a handsome cabinet, whilst

" poker - work " suggestsitself, also, as a possiblemethod of decoratingcases.

using xylonite, ivorineor other material.

Others may like to try their...handat inlay work, using different

Fig. 2.-" Ariel " Cabinet Design.

bought for this purpose from anyhandicraft shop.

Other MethodsThe design in the pho-

tograph is painted directon to the case, and cov-ered with a clear hardvarnish ; but this articleis intended to be sug-gestive, and readers mayhave methods of theirown, by which they canproduce cabinet or caseworthy of the instrumentwhich affords them somuch pleasure, and putssuch enchantments withintheir reach.

Remember that it is the designand not the medium that mattecs !

"-^ , '1.- ' - Nr* We"' \ rWW.efr.1, #'\e,'°%.,^'1., fr W\r'"V W V e 'N,"'\,.. ^'Nr 1e^1, ^1.M.

ON UNKNOWN WAVELENGTHS !L-A,e41.4"..rio"...SW..e.r.v A., W....,Wsr",,e0N.vA.S.N.,,A,,,-SEVERAL women recently broad-

cast a debate on Sunlight.Needless to say, they didn't soft-soapone another.2 L o's new studio .clock has notany , tick. We can sympathisewith it. Our tailor' gets like thatsometimes.A COMPETITOR in a wireless clubraffle recently won a pair- of Germanheadphones. That should teach himto leave gambling severely alone inthe future.AN item in a recent Austrian pro-gramme, " Ten Girls and One. Man,"is described as .a comic opera. Itsounds more like the, curtain raiserto a tragedy. .,

ONE of the American stations hasgiven a talk -on " How to .LiveLong." This is the sort of thing thatwill bring wireless into disrepute-especially amongst undertakers.

COMMANDER KENWOR EH Y has heardhis own voice on the wireless. Whata pity all our M.P.s can't be putthrough this procedure." Wiixr Men Will Do for Gold. " wasbroadcast from a Californian stationa few weeks ago. The answer, ofcourse, is " other men."WE should like to correct the im-pression of the correspondent whothinks. that gang -control originatedat Dartmoor.A B.B.C. correspondent has suggestedthat all 'lectures shall be given in.Esperanto. Evidently a Yorkshire -man who does not understand ordin-ary English.FROM a daily paper : " Wirelessconcerts- were giVen dining the recenthop -picking seas -'n in the Kent hop -fields." (N.B.Some of our olderreaders may remember that hops, inpre-war days, were used as an n-gredient in the brewing of beer).

366

" THRIFT " formed the subject of atalk from Glasgow recently. Wesuggest that " Coal " might similarlybe given from Newcastle.COMING wireless, lectures on " speed "are announced. The Bricklayers'Union are considering whether theyshall strike as a protest.OF the 26 broadcasting stations inSpain, only a I are at work. Nowonder that somebody said the otherday that wireless was " nearlyhuman."A PUBLICAN says that there has beenless drinking in his bar since heinstalled the wireless. Then theprogrammes can't be so dry as somepeople would have us believe.SEVERAL listeners have been com-plaining that too many of the pro-grammes are designed for loud-speaker work. Such as a 5 P Ytalk on Cheshire Cheese, for example.

Wireless Magazine, Not e mber: 1926

NNW

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efficiency by using only

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The Igranic Catalogue No.J130 contains particulars ofall the parts you need forbuilding receivers of the

highest possible efficiency.SEND FOR YOUR COPY NOW.

Igranic Variable Condensershave earned the reputation ofbeing the " choice of experts."Dual Type, as illustrated, '0003mfd. 22/6 ; 0005 mfd. 27/-.Single pattern, '00015 mfd. 17/6 ;'0003 mfd. 18/6 ; '0005 mfd. 21/6;'001 mfd. 25-/.

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In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.

367

Wireless Magazine, Nownthen1926

z

-What Readers Think of Our SetsAZZO:00,92:13,77,4=ZOZ:',(X3=:=7e

,,,,.;-;:;;;;;;,r? 0 /- /

-,4 ,7,9, ..,4,,,,,,.. 5,,,,:,7,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,74.

,,,/,,,,,,,,,,, , i ,ya!,', /,,=-e, s r "Ii., , s , /--:- // ', .3 A

AS GOOD A SET AS MONEYCAN BUY.

February, 1925, p. 20 (No. I).September, 1925, p. 135 (No. 8).March, 1926, p. 121 (No. 14).

In West AustraliaTo the Editor, "Wireless Magazine."

SII2,-Perhaps the following informationmay be useful by way of compariSon

as to what your set, described under theheading of " As Good A Set As MoneyCan Buy,'" is capable of in other coun-tries. Using this set I have received the'following stations regularly :

StationBrisbaneSydneySydneyMelbourneMelbourneAdelaideAdelaideDurban (S. Africa)...Sydney

Call DistanceSign. in Miles.4QG 2,3002FC 2,1002BL 2,1003L0' 1,7003AR 1,7005CL 1,2005DN 1,20(t

5,3002RY 2,100

All stations except the last one can beheard at reasonable strength on a BabyBrown loud -speaker. For the localstation, 6WF (1,2oo metres, with a powerof 5 kilowatts) .only three valves can beused as four make too much sound.

It is interesting to note that the station4QG, Brisbane, is 2,300 miles away overland all the 'why. For Durban, ofcourse,, it is practically water all theway. -1.. SEWELL (Perth).

" Pui-ity and Power "Sta,-Please allow me a few lines of

praise' for your " As Good As MoneyCan Buy " Four-vaiver (first circuit).My set has been in. constant use fortwelve months, and I have refrainedfrom altering the circuit except to use aBretwood variable grid leak, which Ifind gives, the set the finest control overoscillation.

My aerial is an indoor one, 14 feetlong with four strands and two spreaders4 ft. 3 in. wide: With this poor aerial Iwork 2L0, 5XX, 2ZY, 6LV, 2BE,Madrid, Munster, Frankfort, Oslo, anda great many other stations on my loud-speaker. Dublin on three valves is fartoo powerful.

As the power station is not all thatcould be desired, and the' house is fitted

with electric light, I sometimes have agreat deal of interference with the,. dy-namos working, but by, disconnectingthe earth from the set and slightly alter;ing the tuning I can still work Dublinwithout loss of -power, and cut out nearlyall interference. -

Purity and- power are the keynotes ofthis set, and when I have been havinga few friends or, worse still, wirelessfans, to come and hear the set working,it has only once let me down.

I shall not regret the day I started-.wireless and your excellent magazine.-H. HAVES (Holyhead).

" Selective and SensitiveS111;-1 feel that I must let you know

of my success with - another of your 'sets.I constructed your four-valver, " AsGood A Set as Money Can Buy," andhave found it a topper. I have kept toyour circuit, but have altered the lay-out.

All the coils are totally enclosed with-in the cabinet, and here I have introduceda novelty. The anode coil is entirelywrapped up in tinfoil, which. is con-nected to earth. This makes a veryefficient screen and prevents interactionbetween the coils. It .also cuts out alot of interference.

The set is very selective, sensitive andloud. I receive the local station at 25miles, and Daventry at about ifto milesat full loud -speaker strength on threevalves: also about ten other stations(B.B.C. and -foreign). With all fourvalves in use I can almost have any pro-gramme I choose. -

I may say that- I_ have substitutedplugs and jacks in place of terminals sothat I can use two, three or four valvesat will. .

The panel is made of three-ply wood,stained walnut and french polished. Ifound this a great saving and at nosacrifice of efficiency, for all componentson, the panel are at earth potential. Thewhole is enclosed in a cabinet fitted withdoors, and altogether it is a real de luxeset.

I thank you for this, one more of yourmany successful sets.-A. E. RuiTER(Wingate, Co. Durham).

" Delighted With It "SIR,-I have made the four -valve set

named " As Good A Set As Money CanBuy," designed by your staff, which yourecommended as being the most suitableset for my requirements, and thought you

368

would be interested to know I am de-- lighted with it.

When working in conjunction with anAmplion Radiolux loud -speaker it gives

..most remarkable results. From Cardiff,Daventry and Bournemouth reception isbeautifully clear and very natural.Radio -Paris comes in very well on threevalves, but a wavetrap is necessary toseparate it from Daventry when thelatter is broadcasting.

I have heard most of the demonstra-tion sets of all makes up to £50 ormore in the Bristol shops, but' speaking

absolutely without exaggeration none ofthem are so natural or so clear, althoughsome may be louder.

The Amplion Radiolux gives perfectreception but will not take the fourvalves on 5XX or 5WA, so I invariablyuse three valves.

The set is perfect on three valves, butwhen four valves are switched on a cer-tain amount of crackle* comes in whichrather spoils the reception (but even thenis quite as good as most sets).

My many wireless expert friends allare very surprised with the results I getand say it is quite as good a set as theyhave ever heard, and it evidently is" as good a set as money can buy.''

I thank -you very much.-A. J. BROWN-STON (Bristol).

[* We' suggest that these cracklings aredue to atmospherics or some other formof interference external to the set.-ED.]

A NOVEL QUICK -ASSEMBLYCRYSTAL SET.

September, 1926, p. 156 (No. 20).

" Most Wonderful Set"SIR,-I have just completed the crystal

set described in this month's magazine,and I think it is the most wonderfulcrystal set I have ever made.

I have a bought set and I have mademany, and I can say that none- has beenable to compare with the Quick -assemblySet.

Thirty miles off Newcastle is quitestrong, Daventry fairly good. Withmy neighbour working a four -valve setnext door I was able to receive Dublin.I feel that T must sincerely thank thedesigners for furnishing us with detailsof such a perfect little model.-G.WALKER (Eastgate, Co. Durham).

4

S.P. 18RED SPOTA real two - voltpower valve.Designed speciallyfor low frequencyamplification.Should always beused in last stage foroperating loudspeaker. It is alsosuitable as a detectorFil. Volts:Amps.: '3.

PRICE .141-

S.P. 18GREEN SPOT.A high amplificationvalve having a mod-erate impeda nce.Designed as a higghfrequency amplifierand as a detector.Also suitable for re-sistance choke andtrans former coupling(except last stage'where an S.P. 18Red should alwaysbe used).

Fil. Volts: 1.6.Amps.: '3.

PRICE I 41-

S.P.18BLUE SPOT.Extra high ampli-fication valve. De-signed for resistancecapacity, choke andearly stages of trans-formercoupling. Ex-cellent as a detectoror tuned anode N.F.amplifier.Fil. Volts: 1'6.Amps.: '09.

PRICE 141 -

Wireless M agazine, Nowmber 026

cantwoirh,

TEAM WORK counts in Radio too.Unless valves work together har-moniously reception will never be

at its best. That is why BENJAMINValves should be used in every stage.They have been designed as a teamwhich, working together, will give resultsfar sureassing those that can be obtainedwith any other valves, in any other way.

Anode and filament are very closetogether, and therefore the electronstraverse a very short path. This in-creases amplification. A speciallydesigned filament consumes less current.Tone is improved. Ask your dealer orwrite for descriptive leaflet giving curves.

BRILVNLAINSHORTPATH

RADIO VALVESTHE BENJAMIN ELECTRIC LTD.,Brantwood Works, Tottenham, N. 17.

D.E. 55.A very economics;general purposevalve. For highfrequency, detectorand low frequency(except last stage.when the S.P. 55 Redshould always beused).

Fil. Volts:Amps.: '09.

PRICE 1816

S.P. 55BLUE SPOT.Extra high ampli-fication valve. De-signed for resis antecapacity, choke andearly stage trans-former coupling.Also excellent as arectifier or high fre.quency amplifier.Fil. Volts: 5'5.Amps.: '09.

PRICE 18/6

S.P. 55REA SPOT.Super power valvespecially designed asa last stage poweramplifier. Will givegreat power withoutdistortion. Also suit-able for detector orH.F amplifier.Fil. Volts: 5'5.Amps.: '25.

PRICE 2216

In writing to advertisers, please say you saw thz advertiseruzat in thz WIRELESS M%GAZINE.

369

Wireless Magazine. Novemben 19261

GADGETS, HINTS

Improvised Spark GapHOW a sparking plug from a car

can be used to serve, as a safetyspark gap is shown by the diagram.

AERIALDOWNLEAD

EMPTY TIN

WIRECONNECTEDTO EARTHPLATE.

SPARKINGPLUG

111

CRAW=

.11-a

SPARKGAP

LEAD-INTO 5F-15

Details of linprovised Spark Gap.

An earth lead is connected to thelower end of the plug, while screwedunder the nut at the top of the plugis the aerial lead and an old tin. Thetin protects the spark gap from rain.

" Care should be taken to clean thesparking plug before use, otherwisethe efficiency of the aerial system willbe lowered owing to leakage. J. B.

,Unobtrusive Receiving SetTHOSE who have not much space to

spare or who object to the presenceof a large receiving set can overcomethe trouble by utilising a table drawer:ts a cabinet.

The sketch shows how to do this,

DRAWER SUPPORTSTRIP

BATTERYCOMPARTNERT

PANELWITHCONTROLS

Receiver Accommodated in Drawer.

the pane' with the controls mountedon it taking the place of the drawerfront.

Coils and components are mountedinside the drawer and a compartmentleft for batteries. All that need show

when the set is in operation is theloud -speaker connection. B. E.

Neat Battery LeadsHOWEVER handsome may be the

cabinet of a receiver, the effect is

RENEW YOUR H.T.BATTERY FORNATIONAL WIRELESS

WEEK!

always spoilt by long stragglingbattery leads; shown in the sketch is

Neat Arrangement of Battery Leads.,

alla hint which in practice obviatesuntidiness.

Rubber tubing is used, one piecefor the L.T. leads and another for themultiplicity of H.T. leads. As these,wires are bunched together careshould be taken that they are wellinsulated from- one another.

R. S.

Broadcasting ProgrammesDETAILS of the broadcast pro-

grammes, notes and log -books andkindred odds and ends which arerequired when listening -in can beconveniently stored, by means of abracket fixed on the side- of the receiv-ing set itself.

370

The sketch shows one method ofdoing this, in which an oxidisedmetal sheet is shaped as shown. Analternative method would be to use

Receptacle for Programmes.'

thin wood, the same as is used for thecabinet, finished to match it.

R. U. T.

Efficient Lead-inWHEN inconvenient or inefficient to

bring the lead-in tube through thewindow frame, it can .be takenthrough the window pane.

The only diflicultY is in drilling thehole in the glass. The best plan isto take out the pane of glass andcut it in half. Then with a mediumround file cut a groove in the mannershown at A and so produce a semi-circular cut as shown at B.

A corresponding cut is made in theother half of the pane, so that when

Details of Efficient Lead-in.

the two panes are reassembled, as. inthe illustration, a hole is formed toaccommodate the lead-in .tube.

Two rubber washers, one each sideof the glass, hold the tube in posi-tion. I. C. W.

Wireless Magazine, No I ember 1926

r

)

Type " 0." The Unit alone.

Price 8/8

Type " V." A similar unit incorporat-ing the "Cosmos" Spring Valve Holder.

Price 10/6

illustration shows

ITir:v1;0`lvid!inserted.

)

Suitable Valves are-for 2 -volt " Cosmos" S.P.i8/B at 14/-for 5 volt " Cosmos" S.P.55/B at ism

>

061110(S, )

>

ResistancerCoupling Unit

Real purity of reproduction ,>

Even the advertisements of the best Transformers plead guilty toimperfect amplification over the whole musical range. Real purityof reproduction can only be obtained with resistance capacitycoupling. The " Cosmos ' coupling unit with a suitable valve canbe as effective as a transformer -coupled stage. Avoids all distortion

e>and effects considerable economies in first and operating cost.2

Designed primarily for use with the " Cosmos" S.P. Blue SpotValves, it can be used successfully with any valve having an e>

amplification factor of 3o or more. <,

Additional advantages :- ,1 Maximum possible amplification per stage.

2 Economy in filament consumption " Cosmos " S.P BlueSpot Valves consume o.o9 amp.

3 Economy in H.T. battery consumption Less than 1/lothof normal.

4 Immunity from breakdown caused by complete or partialfailure of the windings of transformers or chokes.

5 Small space and light weight

A high-tension battery of 120volts is adequate with this unit _ ....., ,

and " Cosmos " Shortpath BlueSpot Valves.

METRO - VICKSUPPLIES LTD.

Metro -Vick House,155, Charing Cross Rossd,

LONDON, W.C.2.your dealer

for copy of folder <

4117/7, fullycres.cribing this coupling <

unit and its advantages.R

P51 <

In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.371

IWireless Magazine. November 1926

T 1- is excellent news that the13.B.C., 'in conjunction with the

Royal Academy of Dramatic Art,will begin this autumn to train suit-able.dramatic students especially .forbroadcasting. Tke system whichassumes that because you can Writea bright lecturette, or because yourname is well known, you must havea voice and manner suitable for-.

transmission by microphone has beenone of the banes of wireless upto now. -

I have- often been a listener andlost half of each sentence becausethe nervous broadcaster at the otherend dropped his or her voice-a .per-fectly natural habit which it happensthe microphone won't tolerate.

I have -.often, on the. other hand,been :1 contributor to the programme,and have found it a nerve-rackingtask to keep my voice to the rightpitch and speed, avoid rustling paperas the sheets are turned over, and atthe same time infuse snap and per-sonality into my remarks.

Trying ThingsTw-othings about broadcasting, to

the person. who has had no trainingin microphone delivery, are particu-larly trying-the timing and the as -you -go -along criticisms -'Of - the 'an.-nouncer. One eye must be alwayson the clock to see that neither .aminute less nor a min.utemore thanthe allotted span is occupied; and theannouncer, no doubt necessarily, butvery disconcertingly, may glide up atany moment and interject instruc-tions in a stage whisper.

" Will you go more slowly,please.". " Do you mind speaking alittle louder." When you're. alreadyhighly nervous, such remarks do putyou off. But the trained broadcastartist of the 'future will know'betterthan to make these little mistalzesand listening -in will gain thereby.

* * * *If we accept as accurate a recent

definition of jazz as the slang ofmusic (and it seems a good descrip-tion), this appears to throw a freshlight on the many discussions ofto -day concerning the lastingness orotherwise of light syncopated melo-dies. People of classic tastes alwaysinsist that jazz is ephemeral and thatlisteners quickly tire of it, while jazz

enthusiasts declare that the hest of

their favourites will live.Is -slang handed down .to posterit

or does it die in its own generation?To this one can only give both

answers, "Yes"and," No." Many slang words and *lbphrases utterlydisappear in a fewyears as if theyhad never been.On the otherh and;literaryEnglish is ('00-stantly being- en-riched by roguewords whichfro -m b e L.;

sniffed at by 111(learn ed, finda place eventually in the most re-spectable of dictionaries. For in-stance, within the memory of livingpeople " pluck " was considered anabsolutely slang word.

On this analogy there seems somehope for the permanence of a certainamount of jazz music.

A friend. who read my note lastmonth mentioning weaving at atable loom being an ideal manualoccupation to accompany listening -inwrites to me enthusiastically aboutthis handicraft as a hobhy for wire-less " fans."

" I shall be starting the making of.Christmas presents before long," isone of her remarks, " and I intendto get them done on my little loomduring the time devoted each day tothe loud speaker."

Most women like to make manyof their Christmas gifts, if they canonly find the time, and this suggestsa way of doing so without sacrificingwork or any other recreation. Fewof us weave, perhaps,' but the cult ofthe needle -has been enormouslyrevived in the last two or threeyears, and sewing turns out Manya charming -gift, without boredom,if indulged in during listening -inhours.

Women who are choosing a wire-less set without the expert help of amale relative are up against onedifficulty which doesn't seem to have

372

Broadcasting fromthe Melbourne

studio

occurred to radio manufact urcrs-that with their technical ignorancethe imposing names which aregiven to sets are unintelligible tothem.

It's time a woman told thosebusiness firms that a title like" crystal set \vith air -spaced coils "or " reflex set with- valve detector "stirs no chords at all in -the femininebreast.

And what woman ever -earned topossess a set which its makers havecryptically labelled " The ABC forXYZ) Crystal Set "?

Making Equipment InterestingTo make wireless equipment in-

teresting _to women, it should benamed on non -technical and muchmore . homely.' lines. ' " One -valve -amplifier " is a phrase which leavesus cold; but " The Louder -time One -valve Set " sounds interesting andcarries its clainis,to superiority in itstitle.

And we should rush for thecomfort of " Neverache " headphonesand. the cosy fireside intimacy of a" Teatime " loud -speaker.

It seems to me that it might beworth the while of big wireless firmsto pay a retaining fee to an intelli-gent woman who understands thepsychology of her sex. Her, jobwould simply be,- when new modelsof wireless apparatus are launched,to give them titles and descriptionsthat would allure women buyers. aswell as men. A. M. M.

GOLDENCLEAR at a whisper-clear at the heavy volume

of a brass band....the T.M.C. " Concert Grand "brings a wealth of mellowness,

and faithfully reproduces the soundsoriginated in the Broadcasting studio.

The instrument is unequalled for itsfreedom from " throaty " noises, becausethe copper used in the construction ofthe horn is in a natural, unstressed

OTHER T.M.C.RADIO

SPECIALITIES.

LOUD SPEAKERS." Standard " £4. 5.0"Junior" .. £1 .17 .6" Minor " . 17.6CRYSTAL SETS.

From 12s. 6d. to£2 . 7 . 6.

Prices do not apply tothe Irish Free State.

WirelessMagazine. Noventher: 1926

state and its frequency of vibration is out ofrange of that of any note which the loud speaker

may be called upon to reproduce. Itgives that full richness which only coppercan give.

The magnetic system-a vitally importantpart of every loud speaker is theresult of, much study, and experimentalwork. Price £5.10 .0.

THE " GRAMO-SPEAKER " is a little brother to the " Concert Grand."In a moment it will turn your Gramophone into a splendid loud speaker orit can be fitted to home-made or purchased horns of ordinary design. Itmakes a most useful extra loud speaker at a nominal price for your nurseryor for entertaining your domestic staff. It is not an adapted "Earpiece "with the diaphragm held in place by a screw -on cap, ready to loosenthrough its own vibration. It is a real Loud Speaker Unit with an adjustablemagnetic system (Loud Speaker size) fitted with permanent magnets of cobalt steeland a diaphragm firmly clamped between ground metal surfaces. For performance,finish and price, it is the best of its kind.

Ask your dealer to show it to you. Its price is on'y 13/6

OTHER T.M.C.RADIO

SPECIALITIES.HEADPHONES.

No. 3. (Lightweight) e. d.In cardboard box .. 17 6No. ba . Heavier Model 15 0

fled cases 2/8 extra.LOW CAPACITY HEYS.

No. 1. 12 point, 3 s, d.position 7 0

No. 4. 6 point, 2position 6 0

No. 3. 24 point, 3position lb 6

Ask for the newT.M.C. Catalogue.

Telephone Manufacturing Co. Ltd.HOLLINGSWORTH WORKS. WEST DULWICH. S.E.2L'I' t Sy I -tit . t I. 1%.1. " . Dul, m s.

In writing to advertisers, please say you saw the advertisement in the WIRELEss MAGAZINE.

373

IWireiess'Magazine.Novemben49,26

THE new Indian BroadcastingCompany is apparently to enjoy

far more favourable terms than thoseaccorded to the B.B.C. The licencefee is to be fixed at so Rs. or 15s., ofwhich 8o per cent., or 12S., goes tothe company. In addition they willreceive so per cent, of the value of allimported wireless receiving sets andaccessories, and are to be free fromany GovernMent limitation of profitsduring the first .five years.

Two stations are at present incourse of erection, one in Bengal andthe other in Bombay. If these provesuccessful it is intended to establishother centres so as to give an adequatecrystal -set service over the greaterpart of British India.

A Luminous ResonatorW. G. Cady has discovered that it

a small quartz. rod is enclosed in anevacuated glass. -bulb and subjected toan oscillating electromotive force, auniform glow appears around thecrystal when it is. oscillating at itsnatural frequency.. Partial reson-ance, when ,energised by higher har-monic oseillations; results in. -a par-tial illumination of the rod.

The explanation of this extra-ordinary phenomenon- is so far amatter of conjecture, but it hasalready been applied in practice tothe determination, at night, of theelectrical characteristics of an oscil-lating circuit by direct observation ofthe lutninoiss appearance of thecrystal in the dark.

iF *

It can hardly be said that any veryoutstanding note of novelty wasstruck by the exhibits at Olympialast month. A decided improve-ment was, however, to be observedin the design of component parts ingeneral, more particularly. in vari-

c% MONTI"-Thit WO

able condensers, inductance coils, andtransformers.

The standard of 'British practice inthis respect is noticeably in advanceof last year, and there should belittle cause to fear foreign competi-tion in this connection either frontAmerica or. elsewhere.

* *

Lower PricesThe price of multi -valve sets, such

as the supersonic receiver and varioustypes of neutralised circuits, is slowlycoming -within the reach of the manof moderate means. The non4ech-Meal wireless enthusiast must also beencouraged by the simplification thathas been effected in theoperatien of such sets.

A certain advance is Ao be recordedin the general standard of selectivity.We seem to be getting somewhatnearer the standard of the ideal re-ceiver capable of selecting practicallyany- programme at will, even underthe shadow of the local transmittingstation.

Quite an interesting exhibit in thisconnection was the Retrosonic re-ceiver, for which some really remark-able claims are made. This set is cfthe straight variety, in that it doesnot utilise either the supersoniq orneutrodyne principle, nor even a sue: -cession of high -frequency stages.

It depends for its selectivity upona special type of absorber or- trap cir-cuit, the precise details of which havenot yet been published. If the log-ging chart exhibited on the stand isa true record of its normal perform-ance, the set is one of which more willbe heard in the near future.

Dr..Dobson, .in the published ver-sion of his Halley lecture, makessome. important contributions to ourknowledge of conditions in the

374

higher atmosphere. Apart from itseffect upon the passage of wirelesswaves, the ionised upper strata, some-times 'referred to as the Heavisidelayer, is the birthplace of the AuroraBorealis, besides being largely respon-sible for the diurnal variation of theearth's magnetic field.

The Aurora appears to be directlydue to electric discharges caused bycharged particles projected acrossspace from the, sun and trapped in theouter confines of our atmosphere.The actual ionisation of the Heavisidelayer is the result of the direct actionof ultra -violet light in bombarding theindividual air molecules and thus re-leasing some Of the normally -boundelectrons.

Electric currents are in turn set upin these ionised areas by tidal move-ments in the atmosphere similar tothose occurring in the sea, and the'consequence, of these' periodic cur-rents is to be obsen;ed in the weil-known daily fluctuation in the valueof the earth's magnetic field.

P iezo VibrationsA searching investigation has been

made at the National Physical Labora-tory into the nature of the osCilla-tions produced by a quartz resonator,of the type now being used for stabil-ising the wavelength of broadcasttransmitting stations.

As a result it has been calculatedthat a piezo-electric crystal, when inoperation, can be regarded as theequivalent of an electric "loop " cir-cuit, one arm of which comprises in-ductance, resistance, and a condenserin series, the other arm of the" loop " consisting of a shuntcapacity. In addition, an externalseries condenser must be allowed forto cover the capacity effect of the air -

gap in the crystal mounting.B. A. R.

Wireless Magazine, November:1926

4*fir

,, s SWIM

011111011111.............. 111? II 1Ils. ulk,

Sold by all good Radio Dealers

BUY BRITISH HEADPHONESThe British Thomson -Houston Co., Ltd.

In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.375

I Wireless Magazine. Not ember. 1926

WHAT THEkEADEkTH IN 1(cr

1111111111 ;442F -41-.L-1174 1:2-1Z-Ar 1 nu if I L....tw ig r.f rs1 =/0. -e-- ....11==E E L 211M.

Long-distance Crystal ReceptionTo the Editor, "Wireless Magazine."S I Ramon reports long-distance

crystal reception in the OctoberWIRELESS MAGAZINE.

He may be interested to know I haveoften heard the following foreign stationson a simple crystal set :-

Brussels.L'Ecole Superieure.I.e Petit Parisien.Prague (only heard once, when tesL-

ing to America).Madrid (Union Radio Iberica).Konigswusterhausen.Frankfort and Hamburg come in prac-

tically at the same strength as 2L0.-B. DUNN (Stock).

Announcing the Station!Sir,-I believe a better method of

announcing radio stations would hesomething similar to that adopted by theDublin Radio Station, " 2RN. Stationcalling --Dublin."

This method of calling gives thelistener -in. two chances of obtaining thename of the station received, shouldreception be rather weak or Interruptedby atmospherics, etc.-W. HYNOR..

Short-wave CoilsSm.-When building the ",Round -the -

World Shqt-wave Three-valver," des-cribed in the WIRELESS MAGAZINE,February, 1926, I thought of the difficultysome constructors must have whenwinding the coil on the low -loss formerwith the stout No. 16 gauge wire.

I think I hit on a very simple planwhich might be useful to others. In-stead of winding round and round theformer from the reel, very often an ex-asperating job, take- the "doings ''' intothe garden.

Very often there is a staple or otherconvenient fastening in the wall of thehouse and on to this, about 4 ft. abovethe ground, fasten the free end of wireon reel, then walk backwards, and, keep-ing the wire taut, unroll sufficient towind the whole of the two coils -32turns, 33 ft. approximately, with a bitover.

The wire will be straight, perfectly" quiet," and free from twists or 'kinks.Next fasten the free end through the holein former, and taking each end of formerin the fingers turn the former slowly andwalk towards the fixed end.

When 7 turns have been completedhold the wire with left.thumb and takingpliers from pocket cut as directed ; fastenend through` former.

Now reverse the coil foriner, pi( f.free end of wire and start winding asbefore, this time making 25 turns. Cutwire noW nearly. used up and fasten asbefore. Every turn in place, -no movementof wire, and 'easily and quickly done, andsomething to please the eye.

To the writers of letters published eachmonth we award valves. This month'sletter -writers will each receive an EcliswanR bright -emitter valve ; next month'swriters will be sent a B.T.H. R valve each.

s".."....",...."...."...."...."....,"....-0....-"....".0A-...-".

might add 1 tried the above set outlast night and got KDKA first time.=R. SAWYER (Edmonton).

That Mad Feeling!SIR,-What a mad feeling it gives one

YO burn out one's valves ! 7 have doneit twice, burning out -seven valves, and Idare say other amateurs have done thesame thing. What one feels like sayingunder such circumstances is, of course,unprintable !.

Had it not been for this little gadgetwhich- I am about to mention I shouldhave burnt out no less than fifteen valves !

All that has to be done is to insert atorch bulb-not over 3.5 volts for ordinaryuse, but where lower voltages than toovolts are used for H.T. a 2.5 -volt bulbwould be better-in the negative lead ofthe H.T. supply.

Should the valve be carelessly inserted,resulting,- in a " short," or an unpro-tected wire coming -into contact withanother, the torch bulb will immediatelyblow out and save, all 'the valves.

Hoping to benefit others.-H. DAWKES(Durban).

`Sfparate Higktenston:SIR.-I have a three -valve set (H.F.,

detector and L.F.), and -my H.T. is com-posed of two 36 -volt batteries in series;all valves receive the saine. H.T. voltage.

I generally hear four different stationsnightly.

One evening I found an H.T. batteryto be faulty, so 1 put it aside and carriedon with the other. -Toiny amazement Icould stune-in clearly 12. different stations.The II.F. and detector valves were havingtoo much H.T. previously.

I bought a new 36 -volt H.T. batteryand put it in series with the positivephone terminal, giving the. L.F. valveextra voltage. The result was great.

Needless to say,' I am now going togive each valve separate H.T. voltage ; itpays to do so.-L. E. EDWARDS(MaChyaBeth).

376

1?ailway InterferenceStR,--My aerial is about 70 yd. from

the railway station and a big iron rail-way bridge' adjoining it, that crosses theRiver Ouse. The trains cause me a gooddeal of mysterious interference, in theform ciUvery lOud "- knocks " in the loud-speaker or phones.

This is very difficult for me to accountfor as passenger trains (often electricallylit) do not cause so much interference asslowly -moving goods trains. Trainsstanding in the station are sometimesguilty, too. The knocks are as loud aseiyone rapping on the room door andobliterate the words of any speech .heingreceived. -

Fast passenger trains cause fairlyregular knocks, similar to a series ofmorse dots. Slowly -moving goods trainsMake knocks in groups of three or four,a pause of a second or so, then moreknocks. This process goes on until theoffending train is past.

. Have any other readers of " our "magakine experienced it, and, if so, ,canthey put forward any " pet theory " asto the cause?-E. PIERCY (Selby).t.

.

]lore 'Interference.SIR,-Readers may be interested_ in

some experiences and -experiments . Icarried out, last May.. I heard whilstlistening -in a peculiar= buzzing 'sound,and when I turned out my -valves -it eon- -tinned for perhaps' twenty .minutesthough slightly diminished;- also at- in-tervalS I hexed slighter buzzing sounds.

I connected up a crystal set and stillthe bOzies continued, so Is put a pairof phones in circuit 'between two -earthsseparated about six feet apart,. and stillheard them:.

-After thii 'I set out to' look around'outside the house' for perhaps a_radiusof a hundred yards or so, and on investi-gating the various shops I found twobacon -cutting machines at a grocer's, alarge portable hair -drier at a ladies'hair-dressers, and a high -frequency sparkcoil at another, and a motor generatorset at the. cinema.

When any of these instruments ormachines were working I heard thesounds. I came 'to the conclusion thesecurrents or waves I was picking up werenot high -frequency impulses, but eitherinductive effects from the .rapid makingor breaking of a highly inductive' circuit,armature, or trembler coil, or direct mag-netic effects from the same source.

Can any reader give a better explana-tion of the above? If so, I should begrateful.-E. I. R. BELLAS (Wallasey).

Wireless MagaZiiie: November.1926

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In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.377

Wireless Magazine. November 1926

Specially Written by the Officials at Savoy Hill

WHAT THE B.B.C. IS DOING

THE COuncil 'Of the Wireless Re-tailers' Association touched on

a very important matter when theypassed a resolution.expressing theopinion that licence feeS should notbe subject to any deduction :otherthan the actual cost of collection, andthat the amounts already. collectedby the Pokt Office in excess of suchcost should be paid to us.

eve of the Change -over.Now that we are on the eve of the

change -over to Corporation Control,it may not. be amiss to review thefinancial situation and to call atten-tion to ,the tendency which. is becom-ing apparent in some quarters toassess_ the future financial 'require-ments of the service on .the basis ofpast accounts. ..

The presUmptkin is that. pro-grammes: can. be stabilised at theirpresent standard, and 'that too muchlife and spontaneity are opposed tothe interests of listeners. 'That isquite definitely a. view that listenersthemselves do not share, and we havealways maintained that it is a wrongview.

Although we shall soon -be relieved -of our responsibility, it. is due -to lis-teners to recall 'some of the chiefpoints in connection with the financialposition. Under the SupplementaryAgreement of October 1st, 1923, .itwas provided that the amount oflicence collections to be handedover shoUld -be "in such proportionas the Postmaster -General, in con-sultation with the Company, shouldconsider reasonably adequate 'to 'en-able the Company to 'provide a broad-casting service to his reasonable satis-faction."

This clause was interpreted by thePoSt Offiee -as meaning that largeamounts could be withheld from us ;

and while in 1024-1025 our proportionof the liCence fees amounted toZ'489,000,. the amount retained bythe Post Office being Z'tt5,600, wereceived. only .47500,000 in 1025-1926and the PoSt Office retained£284,000.

It might logically be supposed thatif the Post Office share was morethan doubled in the period men-tioned our, revenue should .haveshown a good- deal more expansionthan a mere £11,000.

The 'estimated total ' number oflicences in force at the end of theyear will be 2,100,000, and the amountof.revenue due to broadcasting shouldbe in the neighbourhood of L-;785,000.If, however, the bare cost to the Postoffice of issuing a licence and of allincidental administrative work wereconfined to a shilling, a reform whichwould not involve the Pdst Office in .any loss, the broadcasting servicewould receive about Z.90o,000. Thenpresent standards could .be improvedand present activities extended.

Feeling the PinchOn the programme side we have

been feeling the pinch caused by re-stricted revenue; many additionalthousands of pounds could very wellbe expended on improvements in the'programmes ; further, the officials areunquenchably enthusiastic as con-cerns the big technical developments

e"Ne^1...,s1,-^" e.""

MORE ABOUT THE

1927 FIVEon page 294

378

which have been talked about fromtime to time.

The country wants a new systemof distribution to enable nearly everylistener in Great Britain and NorthernIreland to have the choice of at leasttwo programmes, available simul-taneously, on the cheapest andsimplest apparatus. New regionalhigh -power transmitters are urgentlyrequired, and their cost may be in theneighbourhood of £zoo,000. We haveonly touched the fringe of researchwork during the past four years.There is practically no limit to theamount of money that could usefullybe spent on this branch of broad-casting activity.

Progress-or DeclineA point which we have frequently

emphasised is that the service cannotstand still. If it does not go forward,it must decline. The Corporation,having at its command a highly effi-cient service with considerable capitalassets" and revenue -earning capacity,will, it is hoped, accomplish that pro-

' gressive work from which we,through restricted income, weredebarred.

In view of the fact that we are ex-cluded from taking sides, or of indulg-ing in controversy, it is doubtlessultra vires even to venture the in-offensive observation that the recentstrictures of a modernist poet respect-ing stage artists were unfortunate.

The circumstances are as follows :Mr. Osbert Sitwell, in the course of aPress interview, made the followingremark : " Actors and actresses are sobusy trying to be ladies and gentle-men and golfers that they have notime left to pay attention to theirjobs."

The reason why this remark wasunfortunate, from our point of view,was that it was launched on the eveof a broadcast in which the Sitwelisand Mr. and Miss Wilson Barrett,grandchildren of the great actor ofThe Sign of the Cross fame, werebooked to take part.

Permission WithdrawnMr. Archibald de Bear, the well-

known producer, at once withdrewthe permission which he had givenfor the Wilson Barretts, who weremembers of his revue company, toappear in the studio with the Sitwells,and we were compelled at the lastmoment to obtain substitutes.

It appears, however, that this wasnot what we were expected to do.The Company, we learn, should havecancelled the broadcast entirely, see-ing that it was minus the services ofthe Wilson Barretts ; and should,moreover, have apologised to the stagein general on behalf of Mr. Sitwell.

Obviously, we should have beenparticipating in controversy if we hadtaken sides ; hence our silence wheninvited to express an opinion for pub.lication ; but we must take a firmstand on the question of any indivi-dual's right to dictate what shall orshall not be broadcast.

For a long time prior to the ratifica-tion of the theatrical agreement wemade every effort, and even went outof our way, to cultivate friendly rela-tions with members of the theatricalprofession ; and those relations havecontinued to improve. We have alsostriven to maintain the best relationswith artists who have no connectionwith the stage, with professors andpoliticians, with the Press and theChurch, and, indeed, with everyonewho has been at any time associatedwith broadcasting work.

Not Party to DisputeWe have not been party to any acri-

monious dispute between one sphereof public activity and another, buthave carried on the service in the in-terests of the listening public alone.That task is quite big enough tooccupy all our attention and to taxour ingenuity to the utmost. It iscertain, that all the eminent membersof the stage profession who take partin broadcasting are sufficiently broad-minded to agree that there is nothingin the controversy between the stageand the Sitwells with which we canbe reproached ; to hold any other viewis merely silly.

Wireless Magazine.Novembe/t1926]

Patent Nos. 238003. 223625 and pending.

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-4!

379

.T.6'a

Wireless Magazine, Novemben 1926

A Guide to the Principal European and American Stations.

The New Wavelengths.

NewWave-length

inMetres.

Station. CallSign.

OldWave-length

inMetres

NewWave-length

inMetres.

' Station. CallSign,

OldWave-length

inMetres

Newll'ave-length

in:Metres.

Station. CallSign.

OldWave-length

inMetres

201.3 Karlscrona . . . SMSM r96 Carthagena . . . - 330 416.7 Stockholm . . . SASA 428

204.1 Gefle - 208 Jyvaskyla . -- 301.5 422.6 Rome IRO 425

211.9 Kiev --- 281.9 Leeds 2LS 321.5 428.6 Hamburg - 392.5

2 I .,i Luxemburg . LOAA 1,200 303 Munster - 410 434.8 Bilbao EA J9 415

219 Kovno - 306.1 Bournemouth 6BM 386 441.2 Brunn OKB 521

222.2 Strasburg . . . . - 205 309.3 Marseilles . . . . PTT 351 447.8 Paris FPTT 458

223.9 Leningrad . . . . -- 940 312.5 Newcastle -on- 454.3 New York . . . WJZ

225.6 Belgrade HFF 1,65o Tyne 5NO 404 454.5 Boden SASE 1,200

229 Malmo SASC 270 315.8 Milan - 32o 461.5 Bergen - 357

238.1 Bordeaux . . . . PTT 411 319.1 Dublin 2RN 397 468.8 Elberfeld . . . . - 259

240 Helsingfors . . . - 318 322.4 Mount Prospect W JAZ - 476.2 Lyons PTT 480

241.9 Konigsberg . . . - 462 322.6 Leipzig - 452 483.9 Berlin - 504

245.9250

Toulouse . . .

GleiwitzPTT- 28o

251326.1329.7.

BelfastNuremberg

2BE- 440340

491.5491.8

New York . . .

Aberdeen . . . .

WEAF2BD 495

252.1 Stettin - 241 331.3 Springfield . . . . WBZ. -- -, Birmingham . . 5IT 479

Montpellier . . . - 220 333.3 Reykjavik . .. - 327 500 Zurich ---7- 513

254.2 Kiel - 234.5 337 Copenhagen . . - 347.5 Helsingfors . .. 522

260.9 Gothenburg . . . 'SASB 290 340.9 Paris Petit 333 508.5 Antwerp 265

265.5 Brussels -- . 486 Parisien 517.2 Vienna

272.7 Norrkoping . . SMVY 260 344.8 Seville ' EA J5 357 526.3 Riga - - 480San Sebastian. EA J8 343 348.9 Prague - 368 535.7 Munich - 485

Cassel - 273 353 Cardiff 5WA 353 545.6 Sundsvall . . . . SASD 545

275.2 Zagreb ---:- 350 357.1 Breslau - 418 555.6 Buda Pesth . . - 56o

Madrid (F) . EA J4 340 361.2 Oakland KGO - 566 Orebro - 237..Angers - 275 361.4 London 2L0 365 Berlin - 571

277.8,"

SevilleBarcelona . . .

EA j r7EA J 13

30o462

365.8370.4

GrazOslo

-- 402382

577588.2

MadridLinkoeping .

EA J 6- 392467

' - Caen - 332 375 Madrid EA). 7 373 Vienna - 531

280.4 Barcelona . . . . EA J r gclienectad . .- Wi,Y - - 72o Ostersund . . . . - 720

283 Dortmund - .'. . - - ,324283

.379.5Troy WHAZ - 760 " Geneva HI31 76o

285.7 Reval - 350 379.7 Stuttgart ' ' - 446 8io Odense - - - 8ro

281.5 Edinburgh . . : ...- 2 EH 328 384.6 Manchester . . . 2 tir 378 85o Lausanne HB2 850

' RIM .. . . . . :1, . - 614:11- 335.5 389.6 Radio Toil:rouse - - 430 940 Leningrad . . . . - -..

Plymouth . . ... 5PY 338 394.7 Frankfurt -on- ,,000 Basle - 1,000

Nottingham . . 5NG 326 . .Main - 470 1,010 Moscow Popoff 1,010

Sheffield 6FL 306 400 Bremen - 279 1,060 Hilversum . . . HDO 1,050

Stoke-on-Trent 6ST 301 Aalesund . . . . - - 1,150 Ryvang - 1, I 5o

Liverpool 6LV 331 Koszice ° - 2,020 1,15o Soro - 1,150

Swansea 5SX 482 Warsaw . . . -.- . - 480 1,300 Berlin ... ....... LP . 1,300

Dundee 2DE 315 Falun SMZK 370 1,350 Karlsborg . . . . SA J , , 1,350

291.3 Lyons Radio 28o Cadiz EAJ3 355 1,450 Moscow RDW 1,450

294.1 Liege - 28o Mont de 1,60o Daventry" °

5XX 1,60o

Bilbao .EAJII. 418 Marsan - 390 1,750 Paris SFR -1,750

Trollaattan . . SMXQ 345 405.2 Newark WOR - - 1,800 Norddeich . . . -KAV .1,80oBradford 2LS 310 ' New York . . . WJY - 2, I 25 Amsterdam . . PCFF 2, I 2 3

Dresden --- 294 405.4 Glasgow 5SC 422 2,65o Paris FL 2,65o

297 Agen - 318 411 Berne - 435Hanover . . . .. 297 416.4 Minneapolis . . . WCCO 417

Kovno (given as 219 metres) may work on 344'8 metres ; Leningrad (given as 223'9 and 940 metres) ma.6 wont only

on 434.8 metres; and Helsingfors (given as 240 metres) may work on 375 metres.

380

7

Wireless Magazine. At/member/9261

, Choose yourValvesON CELL ACC/ LATORS

carefully-"Cosmos" DE.1 I

The Pl - Volt Valvethat works well off a

thy battery.flionfrof corrou 0.25 Amp.

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Filament Current o; Thu/5P:c,ition Factor 7.

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wonderful improvement, and the timespent in making the choice is well worthwhile. The comprehensive range of"Cosmos" Valves shown on this page is shownfor convenierce under the general heading ofthe L.T Supply -2 -Volt and 6 -Volt respectively-and some brief particulars are given to indicatetheir chief characteristics.

Particular attention is drawn to the S.P. 18/Band the S.P 55/B (Blue Spot) Valves, which arespecially effective when used with the modernmethod of Resistance Capcity coupling. equal-ling the amplification obtained with L.F.Trans-formers and general purpose valves, with all therecognised advantages of resistance coupling.

Complete details of every valve cannot be given;n the space at our disposal, so, in order to assistyou in making a careful and satisfactory choiceof a valve for each position in your set, thebooklet illustrated below has been producedIt gives all the characteristics and features of theentire range of "Cosmos" Valves, and includesan easily understood table showing the best typesof valves for use in the different positions orstages in various kinds of circuit.Your dealer has a supply of these booklets, The Soul o'Music,- and would be very [leased to give you a copy.

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In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.

381

Wireless Magazine, Nommber 1926

5YM 'writes on Interesting Matters-

1011opo..410C4iL

dEl

AS many of my readers know, I

live in a small village on theborders of Hampshire and Surrey.Though the village is small there area great number of receiving sets inthe neighbourhood, though it' is notso Very long ago that there was onlyone aerial for miles around. Abouta year ago my licence was altered sothat I could work on 44-46 metresand 23 metres at any time of the dayor night, irrespective of broadcasting.

Of course, this presupposed twothings-one was that the neighbour-ing broadcast receivers would bereasonably efficient, and the secondwas that I should so conduct mystation as to make it possible for anefficient receiver a short distanceaway to cut me clean out. All thatwas necessary on my part was aclean emission from my aerial and aclean and sparkless generation ofpower.

With the co-operation of friendlyfolk in various positions, I got mytransmission reasonably right ; butthere was some interference with theless selective sets. I continued toinvestigate all sources of interferencefrom my end, not working duringbroadcast hours, until I have gotthings so that the only set interferedwith is that of my immediate neigh-bour, whose aerial is fifty yards frommine.

" Shock Excitation"What he gets is that which is

known as "shock excitation." When-ever my aerial charges up a currentis induced in his aerial, and he hearsit as a click in his loud -speaker.Fortudately, however, he is a reason-able man; also he dines from eighto'clock until eight -forty-five.

I have thus three-quarters of anhour in the middle of the eveningwhen I can work without disturbinghim, and, also, if I want.to do anyspecial experiment at any other time

he is always willing to shut off forhalf an hour, provided there is notsome specially interesting pro-aramme.

Thus everything is now all rightbut at first, when it was known thatI was investigating, every squeak,howl, or static was put down' to meand duly reported to me as inter-ference caused by my transmitter.On several occasions my neighbourcame in to tell me that interferencewas very bad, when I had not beentransmitting for hours. On one ofthese occasions there was a badthunderstorm about thirty milesaway, and it was really impossible tohear anything decently on the.broad:.cast band!

Set for All WavelengthsThe- building of a set for all wave-

lengths presents many interestingproblems. The tuning condenser forwork on 45 metres should not bebigger than .0003 microfarad when" all in." A small condenser of con-siderably less maximum value isbetter still. Usually it is the bestpolicy to choose the smallest possiblecondenser tha.: will tune from 30 to6o metres with a given inductance;one inductance thus covering thewavelength range on which mostwork is now done. But a very smallvariable condenser greatly restrictsthe tuning range of any given coil onthe higher wavelengths. A com-promise between the conventional.0005 microfarad condenser usuallyfitted to broadcast receivers for aerialtuning. and the very small variablecondenser which gives the very bestresults on short waves must befound. This will be found to be inthe neighbourhood of .0003 micro -farad, at which value a reasonablerange will be given to an inductancefor . broadcast reception, whilst thedifference between minimum and

382

maximum is not so great as to makethe separation of stations too diffi-cult on the closely -packed amateurwavebands. A square -law, or, betterstill, a straight -line -frequency con-denser, is imperative.- For short-waveworking the inductance should be sochOsen that the required wavelengthrange is given on the lower part ofthe condenser scale., Naturally, sincethe set is required for short-wavework as well as medium and long -wave work, one of the many systemsof reaction control which do awaywith the use of a. movable reactioncoil will be used. This will greatlyfacilitate the reception of long-rangebroadcast stations as well as iniprOv-ing the stability of the instrument forordinary working.

At my own station I have. developedmy receiving plant in the oppositedirection. I am using a variometer-tuned receiver with a range of from30 to 5o metres, with a fixed -reactioncoil and parallel -reaction tuning con-denser. A slow-motion dial is fittedto the variometer, which is built withbare, spaced wire, and the wholeinstrument is mast delightful tohandle.

* * * * *

Crystal ControlVery little progress has as yet been

made in this country with crystal -controlled transmitters. One of thedifficulties is the supply of quartzplates with strong oscillating char-acteristics. The other is the fact thatat least two, and probably three,valves have been necessary to workon 45 metres. Recent developmentspoint to the probability that it will bepossible to work crystal control onlow power with one or two valves.Work is being done along these linesat my own station, but so far successseems to be rather elusive. But itwill be done properly by someonebefore long. 5YM.

FREESeason TicketsFor The Zoo

For Members of the

DAILYGRAPHIC

Children's Birthday Club

Photo by Aitken. Ltd

By special arrangement with the Council andSecretary of the Zoological Society, Members ofthe Birthday Club are admitted absolutely freeto London's Zoo.

A little book containing 20 free admission tickets ispresented (whenever written application is madefor them), together with an official Badge ofMembership to each new young reader of the

Daily Graphic " on becoming a Member of theChildren's Birthday Club. These tickets can beused any day of the week except Sundays andMondays right up to the end of the year.

A member has to give up one ticket each time theyvisit the Zoo, and must wear the Membership Badge.

HOW TO BECOME A MEMBERStart collecting now 5o membership coupons, oneof which appears every other day in the " DailyGraphic, ' or, if you do not wish to wait so: longbefore you can become a member, send a postalOrder for 6/6 to the "Daily Graphic," Tallis House,Tallis Street, E.C.4-this being 73 weeks' subscrip-tion-together with one Birthday Coupon (cut fromthe "Daily Graphic "), filled'in and the name andaddress of your nearest newsagent. You will thenbe registered as a member and be entitled to thisfree privilege. In addition to this free treat youwill receive on your birthday, whenever it may fall,a wonderful present-but this will be sent only ifyou join before October 31st.

See the full particulars in the

DAILY GRAPHIC

Wireless /Vow/ober /926 I

IncreasedElectronic mission,

offikunentabout livice that

'lI Ptii4n the astral type,

S.S.2A., H.F. and LF.D.E., P8 volts, 'Iamp., H.F., L.F.,and Detector .. 14/-

S.S.10.D.E., 2 volts, '15amp., Power Ampli-

S.S.7.D.E., 31 volts, .1

amp., Power Ampli-

1816

18/6S.S.8.

D.E., 3-4 volts, Iamp., General Pur-pose .. 14/ -

These Prices do not applyin the lrist Free State.

Comparative 73iagramSIX -SIXTY

F- - I _

ORDINARYI

SEEING is believing. It isobvious from the construc-tion of the Six -Sixty Duo -

Triangular system of Suspensionthat the length of filament em-ployed is almost twice that in theusual type of design, representedby broken lines. Now this in-creased length of filament mustresult in a corresponding in-crease in electronic emission, andif in turn all this valuable elec-tron stream is utilised, thengreater efficiency must ensue.

In the early days of the radio valve,the length of filament in the old typeof cylindrical construction may havebeen relatively great, but a very largeproportion of the electron stream waslost. The design of the new Six -SixtyPoint One Valves is such that the entirefilament-supported at each cornerof both triangles-is wholly enclosedwithin the grid and anode, and thereforeall the electron stream is utilised.

Then too, the stability and perfectalignment resulting from the additionalsupports render it unnecessary toassemble the filament in tension, andensure a constancy of perfect reception.

And remember, the special Six -Sixtyfilament itself is wonderfully economical.Its current consumption is barely'I amp., and when operating at therated voltage there is absolutely nosign of " glow."

The new Six -Sixty Point One Valves-embodying all the advantages ofDuo -Triangular Filament Suspension-are suitable for operation in all stagesof a receiver, whether the L.T. supplybe 2, 4, or 6 volts.

After exacting and exhaustive tests,Messrs. A. J. Stevens (1914) Ltd.have decided to standardise SIX -SIXTY valves in their famous" Symphony " Range of Receivers.Descriptive leaflet S.S.9 -26, with par-ticulars of complete range, free on application

SIX -SIXTY VALVESBetter by Six Tunes Sixty

The Electron Co., Ltd., Triumph House, 189, Regent St., LONDON, W.I.

383

Wireless Magazine,Abvember: .196

UESTIONS

SIMPLYANSWEW

Oscillating -crystal CircuitsQ.-Can you give me circuits making

use of an oscillating crystal as an H.F.amplifier and as an L.F. amplifier?-H. W. H. (Keyworth).

-H.E AMPLIFIER-.

1 MFD

1.100 - 3000OHMS

T -4 VOLT5 8 VOLTS 'Z INCITE

I1? 75 COILFOR 2 LO.

ANY CRYSTALVALUES TO DETECTOR,SUIT WAVELEMTIf

DESIREDA

-RECEIVER-.

LOW- RATIOTRANSFORMER

1000 OR 1500OHMS --?

4 VOLTS

_9_9

-L.E AMPLIFIER-.

I17 TO ao VOLTS

Oscillating -crystal Circuits.

A.-The circuits are shown here.The L.F. amplifier will not prove to beas efficient as the H.F. amplifier whentried out, but gives about a 3 to i am-plification factor ; the H.F. should beabout 15 to t. You are advised to buytested zincite and have it fused in anarc; with good zincite no great difficultywill be found in getting the crystal tooscillate.-S. H. D.

Adding Grid BiasQ.-As I experience some distortion

from my receiver I would like to add grid

bias to obviate this. Can you explainhow this may be added?-J. C. (Dover).

A.-Disconnect the I.S. terminals ofeach L.F. transformer from negativeLT., now connect the positive terminalof the grid battery to L.T.- and wireeach I.S. terminal to a separate negativewander plug for attaching to the negativeside of the grid battery.-L. A. C.

Neutralising a StandardThree-valver

Q.-1 have a three-valye tuned -anode11.F. detector and L.F. receiver, andwish to neutralise the H.F. stage and soovercome the oscillation nuisance.might mention that a potentiometer isnot used in my set. Can you explain howI may effect the above?-P. R. (Dorking).

A.-The method we advise is asfollows :-Fit another single coil holderby the side of your present anode coil andconnect one side of the coil holder to thegrid of the H.F. valve, the other sidebeing connected to one terminal o. aneutralising condenser. Connect theother terminal of this condenser to L.T.A No. 15o coil inserted in this extraholder will be about correct for ordinarybroadcast reception.-L. A. C.

Accumulator -chargingDifficulties

Q.-Having difficulty in getting myaccumulators charged locally, I hate in-stalled a dynamo and an accumulator -charging panel. I am puzzled, however,becauSe my Voltmeter will only show 3

YOUR QUESTIONSANSWERED

Instead of worrying yourself withknotty problems, let the Technical Staff

of the WIRELESS MAGAZINE answer

your questions for you.

Replies of general interest will be

published each month, but a post reply

will be sent without delay to every

querist.

Ask one question at a time; writeon one side of the paper only ; attach

to it the coupon on cover iii : and

send it with a stamped addressed reply

envelope to : The Editor, WIRELESS

5 M1G SZINE. La Belle Sauvage, E.C.4

N.....4..."......"......."....."...."....,

384

or 4 volts, whatever the state of chargemay be in the cells. Is there anythingwrong 'with my connections, of whicha sketch is enclosed?-W. T. (Seaford).

A.-The equipment appears from the

IIIICUTOUT

AMMETER)

D NAr413

BATTERY

D.P.SWITCH

VOLTMETER

Connections ofCharging Plant.

sketch to consist of a dynamo with fourterminals only, one of which is earthedto the frame, a double -pole main switch,an automatic cut -in and cut-out, am-meter, variable resistance, two chargingterminals, and three dynamo terminals.

It is hard to know exactly what thedynamo connections are from the fewdetails supplied, and the same applies tothe cut-out.

The variable resistance appears to forman independent circuit from the cell cir-cuit, but without knowing the arrange-ment of the dynamo connections one can-not be certain if it is meant to use thisas a shunt regulator, or as a series re-sistance between the dynamo and cells inthe main charging circuit.

The only thing quite certain is thatthe voltmeter is wrongly placed, as itmeasures the potential after current haspassed through the cut-out coil and con-sequently the voltage drop due to coil re-sistance causes it to give a lower read-ing than the dynamo or the cell voltage.

As the circuit submitted is so involveda simplified diagram has been preparedand is given herewith, on the assumptionthat the dynamo is shunt wound, withseparate main and shunt terminals, oneterminal of each being earthed.-A. H. C.

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Carr. paid to your door in 24 hours.2 v. 1/-, 4 v. 1/8, 6 v. 2/ -

DO YOU KNOW we can rebuildyour L.T. Battery under 6 months'guarantee, at a low coat. It be-yond repair, scrap allowance off -

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SEND IT NOW.'Phone : MUSEUM 6703.

MAXELBATTERY & Co Maxel House, 28 Clip,,toneELECTRICAL 'LA./ Street, Gt. Portland Street, W.I

Get the bestout of your set

You can do thisby reading

"Amateur Wireless"WEEK by week it contains

useful constructionalarticles, written by experts,

and helpful contributions on newdevelopments and novelties, allprofusely illustrated.If you are in any difficulty, writeto "Amateur Wireless" and ananswer to your query, withdiagrams if necessary, will be sentby post free of charge.

See this week's issue of

33 Every

Cassell's, London, E.C.4

Thursday.

Wireless Magazine. Novemben.1926

Here's Proof thatthe 'LOTUS Survives

Shock and isanti-microphonic!

Prices :CornbinalonGRID LEAKand VALVE

HOLDER

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and fixed to tailboard of a Fordmotor lorry, driven over roughroads for 30 miles survived thetest.

At the finish each spring wasas it started - perfect. Nodamage or looseness at the con-nection of leg socket and spring-no valve became loose fromthe holder. Both were elec-trically perfect all the way.

That is why we guarantee thesecurity of Lotus Valve Holdersagainst shocks and vibration.

Fit the Lotus to your set andprotect your valves.

From all Radio Dealers

yALV:(MOLDERPat. No. 256833.

Made from best bakelite mouldingwith springs of nickel silver and

phosphor bronze valve sockets.

GARNETT, WHITELEY & CO., LTD.,Lotus Works, Broadgreen Rd., Liverpool.Makers of the famous "Lotus " 'ernier Coil Holder.

In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.385

Wireless Magazine. 1Voix. tn ben 1926

069~9088800,94,1800~9081009m/W

BEHIND YOURPANEL

Your coils are hiddsn away. but with this im-proved coil holder the position of the movingcoil is no secret - the angle of coupling isclearly shown on the dial.

NEW TRUE I Ion -in coils (No.343) are v ound

under Burwleptatent No. 168249,

and mounted enthe TRU lo e-loPplug which hasminimum capacityend highest insula-tion. Prices from2'3 (No. 85/ to 4.6(No. 250).

T. e t r isle- is 'seared 4 to 1 ardmoves at wrath, the same speedas t e coil. T.:0 coil phros eremrunt:d at en asole to savetea' e and rive better control.Gue tole Brine. Black or obi eengraved dial (No 272, 5'S.

ERIC J. LEVER, 33. Clerlenwell Green, London, E.C.1'Phone: ('lee k we 1 3514/5.

And at Birmingham, Liverpool, Glasgow. etc.

.) EQUIRED. Capable, trustworthy men withIt spare time wbo wish to substantially increaseincome where we are not fully represented.Applicants must have practical knowledge ofiistallation of Set and Aerial, be Householdersor live with parents, and be able to give references;state age and experience. Address Dept. 29,General Radio Company Limited, RadioHouse, Regen. Street, London, W 1.

THE WE I' H.T. BATTERYAll British Made Leelanche Cells.

Glass Ogle, 21 5 15 round or square tree doz.21 x 15 comet only

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Fre on receipt of stomped envelope.THE ETON GLASS BATTERY COMPANY,

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1/8

Talks aboutWireless

by SIROLIVER LODGE

" Both beginners and advancedstudents all the world over willeagerly peruse this hook - DailyGraphic. Illustrated, Cloth, 5s. net.

Casson's London,E.C.4.

ontinentalNotesOF course, you all know Radiolo !

On every occasion when youhave listened to Radio -Paris youmust have been struck by his breezyannouncements. Radiolo was the" cloak of anonymity " with whichthis station tried to disguise Mons.Marcel Laporte. For nearly fouryears he acted as sole announcer atthe Radio -Paris studio. -

By. the time these notes are inprint, Eowever, I am very muchafraid you will hear his voice nomore, as I am told he is relinquish-ing his duties to return to the stage.

Ilis CareerMarcel LaPorte began his career as

an employee on the Paris -Lyons-Mediterranean Railway; since thenhe has been both actor and im-presario.

But I will let you into a secret.Owing to the extended hours of thetransmissions, Laporte could notalwayS be on duty at the Radio -Parisstudio, and during the last fewmonths a second Radiolo waschoSen to..double the part of an-nouncer, in view of the dose simi-larity in voice.

But Monsieur Andre Gaudelette,although endeavouring to copy theoriginal, is -not an actor by profession ;he is a Professor of Latin and Greekat the Paris University. It was onlyby sheer . coincidence that he waschosen for the job.

I wonder whether the present an-nouncer will possess the talent oflending a romantic touch to marketprices and stock exchange quota-tions!. Radiolo chanted these baldfacts as if they had formed part of arecitation in grand opera.

For the coming winter season theBerlin broadcasting station proposesto give to its listeners one operaticperformance each week. Arrange-ments' have be(,n made by whichtwenty-four works are to be relayedfrom Berlin theatres during theseason, namely, sixteen from theState, and eight from the municipalopera houses.

From the studio a further twentyoperas are to he broadcast this winter,

386

and the programme includes namesof famous composers from all periods,from the antiquated Gluck to theultra -modern Strauss.

The average Berliner is a greatlover of high-class music, and theGerman capital is in the favouredposition of being able to afford fouropera houses, which during tenmonths of the year are packed fromfloor to ceiling.

As you are aware, most of theBerlin concerts are relayed to theK on igsw u s terh ause n high - powertransmitter, but during the last fewweeks a simultaneous broadcast hasalso been given by a 3 -kilowattstation on a wavelength of 54 metres.

Although these tests were purely ofan experimental nature, they havebeen highly satisfactory inasmuch asfrom a number of foreign reports re-ceived they have conclusively provedthat the transmissions on the shorterwave, although of less initial powerthan the regular broadcast, have beenpicked up at very considerable dis-tances.

Mark you, in each case, listenershave dilated on the fact that their re-ception had been marred by neitheratmospherics nor morse !

Short WavesIn view of the fact that concerts oh

the low wavelengths put out byU.S.A. stations are now regularly re-ceived in Central Russia on simpleone -valuers, with aerial reaction, itis also proposed to erect an experi-mental transmitter at Vienna inparallel with the Rosenhuegel station.Reports all() reach me that bothMoscow and Leningrad contemplatesimilar plants.

Should all these plans mature, itappears to me that in this kingdomwe are not making true progress. Asit is, in view of the increased powerof some of the Continental stations-Germans, in particular-many lis-teners in this country secure recep-tion of foreign concerts on ordinarycrystal receivers; in fact, cases are re-ported where the foreigner has cutout the local transmission.

(Continued on page 388)

THE 1927 FIVESet of Special Coils with bases A2 : 15s.Set of 4 Aluminium Shield Plates 12s. per setSet of 5 Magnum Resistors 12s. 6d. per setNO TE .-When ordering Resistors please state make and

type of valves used and voltage of accumulator.

Set of Magnaformersas used in "The Cos-mopolitan N i n e,"including 3 Type Aand 2 Type B £5

Aluminium Shield as usedin W.M. Shield Unit 5S.

Send Stamp for Comprehensire Range of Lists.

MAGNUM COMPONENTS are FULLY GUARANTEED

BURNE-JONES & CO., LTD.,Manufacturing Radio Engineers,

Magnum House,296, BOROUGH HIGH ST., LONDON, S.E.1

Telephone Hop 6257. Telegrams: "Burjomag, Sadist, London...Cables Burjomag, London."

Speakir of DULL EMITTERSWhy not -use the

s WI, use `7"a fi.."t- LUSTROLUXecoromy

*,,* valves calling i(i/14-112:i,munc;i....6 andc Power ValJe-

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\--"' for Two -point- wa..?ej 415' j",/ each workingsomething orThree. Kheostal-s ? )

Point -something

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. e accumulator ' or treble theik.( '-' I I

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charge; the valvesthemselves

,_lver"ifyouAperieci-Three-,j,"LUSTROLUX" -Vva

2 woo --06 amp H -F ;') " coshing only ;64,F. cost 9Leack (. 4 294 For valves,-the power valve, v.*/ and using only2 volt .34 amp..- 46 amps!COSFS only -WRar5 more

nf-

7LUSTROLUX" IS/ ALL- BRITIS H!

)

o1

ASK YOUR DEALER

Valves also obtainable from Lewis's Ltd.,Liverpool and Manchester, and

LUSTROLUX LTD.,West Bollington, near Macclesfield.

Send for Catalogue

Wireless Magazine, November; 1926]

itmlimiiiimmilimiliiiiiiiiiiimnifilliiiiiimmilliiiiiiiiiiiiiiiiiimmiliiimmim

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=Be up - to - date z--Have you seen our new ILLUMINATED DIAL FORDEAD HAIR -LINE TUNING? If not this is a

revelation. E=

DO NOT FAIL TO CALL AT OUR SHOWROOMS Eand witness a demonstration of this latest valuable adjunct g.to perfect reception. Price to fit any condenser 20-

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The marvellous long range circuit with the singlecontrol. ON SHOW IN OUR WINDOWS. =

==OUR INTERNATIONAL RADIO CATALOGUE EE(3rd Edition) will be sent to all enthusiasts E

F sending 6d. to cover cost of postage and packing. E== =--=

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In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.

387

WirelessMagazine.November1926

The latest inJacks ictiu#s

LOTUS JACKSWITCHES

This push-pullswitch is designedto occupy the mini-mum space, beingonly x fin. deep. Ofthe finest Bakelite,it has nickel silversprings and con-tacts of pure silver.Soldering contactscan be made to suitany wiring.

PRICES:No. q, as A/illustratedOthers from 2/9

LOTUS JACKDesigned to takeup the least space,the depth back ofpanel being if in.Made from bestBakelite mouldingswith nickel silversprings and puresilver contacts.One -hole fixing.Soldering contactscan be brought intoany position.

PRICES:

illustratedNo. 3, as 2/6

Others from2/. to 3i -

LOTUS JACKPLUGS

Designed for usewith Lotus Jacks.Made from bestBakelite mouldingsand nickel -platedbrass. To fix, thewires are placed inslots and gripped inposition by a turnof the screw cams.

PRICE 2/ -

Radio Dealers.

loonJACKS-SWITCHESPLUCi

Garnett, Whiteley & Co., Ltd.LOTUS Works, Broadgre:Ji Road, Liverpool.

Continental Notes (continued)

With the readjustment of Europeanwavelengths, it is hoped that the con-ditions may be bettered, but there stillremains the fact that in some parts ofthe United Kingdom the listener cansecure greater volume by tuning -into the Continent.

The growth in the number of valvesets on this side must be surely dueto the fact that on any evening it isnow possible to hear .transmissionsfrom several European broadcastingcentres.

A Gernzan StationSince my last notes were published

we must add the name of a furtherGerman broadcaster to our list. Itis that of the Free City of Danzigwhich, transmitting on a wavelengthof 272.7 metres for the present, relaysthe bulk of its programmes from. itsneighbour, Konigsberg.

In the same way as a railwaystation dumped down in a thinly -populated district soon sees a smalltown grow around it, so the adventof a broadcasting plant, be it onlya studio, rapidly increases the num-ber of local licensed listeners.

Although Danzig may from timeto time supply its own radio enter-tainment, it is fully expected thatwithin the next three months its fol-lowing will have so grown in size thatit will be possible to make the stationan independent one, convert it fromrelay to main, and increase its power.

This is all to the good, for it pro-vkles an extra opportunity to the dis-tant " fan " to listen to local celebra-tions and fetes, thus giving him, bythis means, a closer insight into, theartistry of yet another corner of theworld.

* * *

Of all European countries, thereappears to be little doubt that Ger-many to -day is the one showing thegreatest enterprise in the extension ofits broadcasting service. Apart fromthe present installation of a new 6o -kilowatt transmitter at Langenberg(Rhineland), and the proposed in-crease of the Konigswusterhausenplant to twice that power, plans arenow being put forward for the con-struction of a further relay station atFreiburg, in Baden.

In reality, the new scheme isdirected to satisfy the requirements of

388

the very large number of Alsatianswho have immigrated to that districtsince the return of. Alsace-Lorraine toFrance. It is proposed to relay aportion of the Stuttgart programmes,to utilise the existing studio at Mann-heim, and to install a further one inthe city of Karlsruhe. Freiburg itselfwill supply performances from theMunicipal Playhouse, as well asdialect plays from the local AlsatianTheatre.

There appears little doubt that thenew transmitter will be used for the -purposes of propaganda, as in view ofthe fact that the French Posts andTelegraphs Department are so dila-tory in their undertakings, the city ofStrassburg finds itself for the presentwithout any broadcasting service. ItsGerman-born inhabitants must, there-fore, look forward with pleasure toentertainments supplied from over theborder.

For the present, transmissionsfrom the land of the Soviets remain" wropt in mystery." From reportswhich are received there appears verylittle doubt that broadcasts from Mos-cow, at least, are well received incertain portions of the United King-dom. Curiously enough, most ofthese proofs are given by listenersfrom the Midland districts, and it isseldom that the Russian concertshave been heard in London.

Increased Power for RDWFor mans, months past rumours

have been current regarding the in-crease in power of the Moscow(RDW) transmitter to too kilowatts.At the time these notes are writtenthe official Radio Peredacha pro-grammes still give the energy of thatstation as 15 kilowatts. It should,however, be borne in mind that Mos-cow (RDW) and Chablovka, of whichso much has been said, are two dif-ferent stations, the latter lying atsome little distance to the south-eastof Moscow.

The plans of the U.S.S.R. were tocombine all broadcast telephony trans-mitters in one locality, namely, atChablovka, under the title of Komin-tern. The smaller plants scatteredover the capital would then bescrapped. JAY COOTS.

WE reproduce above photographshowing the Terminal Strip ofthe W.M. 1927-FIVE Set,

showing Eastick's "Eelex"Terminal System used through-out. These are now made incomplete range of tops with 32different indications, Polaritybeing clearly shown in red andblack.

Write for Latest Price ListNOW.

No. 5.

WirelessMagazine.Nowmber/924

W31. 102.7---17VE.

Reproduced from Wireless Magazine" Oct. 1926.

THE " EELEX "TREBLE DUTYTERMINAL.

WHERE adaptability, inter-n changeability and perfect con-nection are required, the t' Eelex"System of Standardized Plugsand Sockets is indispensable.This system is used in ;the manyspecifications of all the leadini,Wireless Tapers.

Kote.-The " Eelex " System ofStandardized Plugs and Socketsis demonstrated at ManchesterExhibition and can be obtainedthrough all leading WirelessStores and Dealers.

. . ASTICK& ONS---j'itJ _...._ ...118, DUNHILL ROW, LONDON, E.G.

1M8Emaimp,71N14

TELEPHONE No.: CLERK. 9282.

"1927Five"Setas described- in the October " Wireless Magazine."

Set of 3 BECOL Low Loss Coil Formers

and Discs for Low Wave Lengths 12/6Ready to receive fittings and Windings per set

Set of 3 BECK Low Loss Coil Formers

and Discs for High Wave LengthsReady to receive fittings and Windings

Packing and Postage 9d. extra.

DELIVERYFROM

STOCK.

Registered Trade Mark.

12/6per set

Panels for this set, size 271"x 7" x R2 Quality, mat

surface, 9;4.Superfine highly polished deLuxe, 24,C.Mahogany grained highlypolished, 16!.All ready for use, not drilled.

Packing andpostage I I- extra.

THE BRITISH EBONITE COMPANY LTD.,Nightingale Road, Hanwell, London, W.7.

389

/a solves yoursoldering

roblems for everNo Flome-Constructor can afford to be withoutthe Fluxite Soldering Set, for not only does itmake soldering simpler and neater, but thejoints will always provide perfect contact withconsequent better reception. The FluxiteSoldering Set is exceptionally suited for Wire-less ; it is simple and compact, and will lasttor ever. It contains a special " small-4)ace "soldering iron with non -heating metal handle,a really efficient pocket blow -lamp, Fluxite,solder and full instructions.

All Hardware and Iron-mongery Stores sell theFluxite Soldering Set, 716complete. Fluxite canalso be had in tinsprice 8d.,1 /4 & 2,8.

FLUME LTD.Wept. 832,.Rotherhithe.S.E.113.

FLUOneFOODD

ITE

Wireless Magazine, Mvemben 1926

The 1927 Five. ,Cabinet and Baseboard 2 15Mahoganite Panel (27iin. x 7in.) 162 Terminal Strips and Terminals 7

I Variable Condenser (0'0005) 182 Variable Condensers (0'0003) 1 9

3 Mahoganite Dials (4in.) 10I Milliammeter, Panel -type, 0/10 1 6Set of Magnum Coils with Bases 2 154 Aluminium Shields (Magnum) 122 Neutralising Condensers 9

5 Benjamin Valyeholders 135 Magnum Fixed Resistors 122 Grid Condensers (0'00025) 5

2 Gridleaks (3 and 5 Meg.) 5

2 Jacks and 1 Plug 8

3 F'ixed Condensers (I mfd.) 11

2 Marconiphone Ideal Transformers(21/1 and 4/1). 2 10

I Fixed Condenser (0'0003) 2

Connecting Wire and Sundries .. . 2

£17 9 0

A special department exists to deal with en-quiries and orders for components requiredfor sets described in the WIRELESS MAGAZINEIntending constructors ofTHE COMPACTOPHONE FIVE (Aug.)THE EASY -TO -TUNE TWO

VALVER (Aug.)THE FIRESIDE FOUR ...... (Sept.)THE SHIELD UNIT (Sept.)COSMOPOLITAN NINE (Sept./Oct./Nov.)THE MUSIC LOVER'S THREE . (Oct.)THE MINIATURE TWO-VALVER (Nov.)CRYSTAL SET AND WAVE TRAP (Nov.)may order the specified components from uswith every confidence. Carriage paid on allcash orders value £2 and over (£5 orders foroverseas). Please send stamp for list.

Omnora Ltd., HomSepetiltsrtri"258, New Cross Road, London, S.E.14.

2 VALVE AMPLIFIER, 35/-I Valve Amplifier, 20,,, as new; Valves, D.E..06,7/-;Headphones, 81 pair ; New 4 -Volt Accumulator, 13/ -new 60 -Volt H T., guaranteed, 2 -Valve 411 -Station;let, S4. Approval willingly.

Write for free bargain het.M. Taylor, 67, Studley Rd., Stockwell, London.

PICKEI S CABINETWORKS

For Cabinets to improveyour Set!

To YOUR OWN Panelsizes in many Artistic

Designs.Write for Latest Dcsigss.

Pickett Bros. (W.M.)Works, Bexlc, heath

For Buying and Sellingeverything on Earth

THE BAZAARExchange and Mart

3d. Every Thursday and Saturday.For nearly 6o years the favourite home -paperof Britain and the leading Journal for allkinds of private sale and exchange advertise-ments. On sale at all newsagents.

Send for free specimen copy (mention this paper).

The Bazaar, Exchange and Mart,54, Fetter Lane, London, E.C.4.

CONCLUSIVE procf of the efficiency`---4 of Lotus valve holders is furnishedin a description of a novel test which wasmade recently, which forms the subject ofa pamphlet sent to us by Garnett White-ley & Co., Ltd., of Lotus Works, BroadGreen Road, Liverpool.

An instructive leaflet entitled Aids toBetter Reception and the latest price listof small radio measuring instrumentsare two new publications recently re-ceived from the Sifam Electrical Instru-ment Co., of o5, Oueen Victoria Street,London, E.C.4.

" Press -button " sets are the subject ofan interesting leaflet received fromFelcourt Products, Ltd., of Great Fel-court, East Grinstead.

Particulars of an umbrella -type portableaerial have been sent us by HaroldAshton, A.M.I.E.E., of 8-1o, Bull'sHead Chambers, Hopwood Avenue, Man-chester.

Full particulars of Symphony receiversare given in a well -printed catalogue re-ceived from A. J. Stevens (tom), Ltd., of122-124, Charing Cross Road, W.C.2.

Containing 28 pages, an interestingbooklet entitled " Concerning Dubilier,"has just been issued by the Dubilier Con-denser Co. (1925), Ltd., of Victoria Road,North Acton, W.3.

Wireless -cabinet parcels are dealt within the new catalogue issued by Hobbies,Ltd., of Dereham, Norfolk, at 9d.

Gambrel! " mains " receivers are thesubject of leaflets obtainable from Gam-brel! Bros., Ltd., of 76, Victoria Street,

Liberty sets and components arewith in a catalogue issued by the Radi-Arc Electrical Co., Ltd., of BennettStreet, Chiswick, \V.4.

" The Gentle Art of Choosing One'sPanel " is the title of an interestingbooklet, issued by the American HardRubber Co. (Britain), Ltd., of 13a, ForeStreet, E.C.2, which can be obtained bysending a stamped addressed envelope.

Leaflets received from the ElectronCo.,' Ltd., of 189, Regent Street, W.x,give details of additions to the Six -sixtyrange of Valves..

From the General Radio Co., Ltd., of235, Regent Street, W.x, we havereceived booklets dealing with new andimproved apparatus.

Two new valves 'are the subject of afolder sent us by the Edison Swan ElectricCo., Ltd., of 123-5, Queen VictoriaStreet, E.C.4.

From W. & G. Foyle, the well-knownbooksellers, we have received a catalogueof technical (including wireless) publica-tions. The . firm's address is justBCM /Foyle, NV. C. z .

All kinds of Becol ebonite panels, tubesand dials are dealt with in a bookletissued by the British Ebonite Co., Ltd.,of Nightingale Roatl, Hanwell, W.7.

A new loud -speaker called the Desmo isannounced by Desmo, Ltd., of 31, Staf-ford Street, Birmingham.

A 36 -page catalogue received fromRadio Instruments, Ltd., of 12, HydeStreet, New Oxford Street, W.C.describes new lines in R.I. receivers andcomponents.

Leaflets and .booklets describing theEthodyne and Ethophone sets and com-ponents have been sent us by BurndeptWireless, Ltd., of Blackheath, S.E..3.

The new Cosmos resistance -couplingunit is described in a folder received fromMetro -Vick Supplies, Ltd., of TraffordPark, Manchester.

Copies of the new Marconiphone andSterling log book can be obtained free of !charge on application to the Marcpni-phone Co., Ltd., of 210-2-z2, TottenhamCourt Road,

Triumph components are the subject ofa folder received from A. IL Clackson,Ltd., of 119, Fleet Street, E.C.4..

Copies of the Osram Wireless Guidecan be obtained on application to theGeneral Electric Co., Ltd., of Magnet ;House, Kingsway, W.C.2.

By sending for a selection of the catalogues and pamphletsmentioned above you will be able to keep in touch with the latestdevelopments in the design of wireless apparatus.

Unless otherwise stated, copies of the publications will be sentfree and post free if readers mention the WIRELESS MAGAZINE

when writing.

390

"AMATEURMECHANIC 6WORK" HANDBOOKS

Each

Inet

These are practical manuals, illustratedwith useful explanatory diagrams anddrawings. Each one, edited or writtenby experts, is a textbook for theamateur and a book of reference forthe proficient.

The Joy of Accomplishingis increased by

these books

1/6 SeriesBasket MakingBookbindingBuilding Model YachtsClock Cleaning and RepairingDomestic JobbingDynamo and Electric -Motor BuildingElectric ClocksElectric Primary BatteriesElectro-platingGilding, Silvering and BronzingInduction CoilsKnotting and Splicing Ropes and CordageMagneto Repair and AdjustmentMiniature Electric LightingOxy-Acetylene WeldingPianosTailoringTaxidermyTinplate WorkWatch Cleaning and Repairing

2/- SeriesThe Practical Motor CyclistMotoring for the Owner -DriverElectrical Toys and Tricks

Of all Newsagents and Booksellersor by post 3d. extra from theEditor, Amateur Mechanic, LaBelle Sauvage, E.C.4.

alSend post card for complete list ofthese Handbooks to CASSELL &CO., La Belle Sauvage, E.C.4.

..r.

391

Cassell's, London, E.C.4

The "Wireless Magazine" Buyers' Guide(Numbers in brackets Indicate issue in which advertisement appeared.)

Accumulators and Batteries PAGEDubilier Condenser Co.,

Ltd. . . . (No. 22) 292General Electric Co., Ltd.

(No. 12) 658Maxel Battery and Ac-*

cumulator Co. . (No. 22) 385Rotas (Motor Accessories),

Ltd. . . . (No. 12) 663Siemens Bros. & Co., Ltd.

(No. 12) 654Tungstone Accumulators

(No. 22) Cover iiC. A. Vandervell & Co. (No. 18) 524

Battery ChargersPhilips Lamps, Ltd. (No. 12) 633

Books and PublicationsCassell & Co., Ltd.

(No. 22) 385,Bazaar, Exchange 6- Mart

(No. 22)Daily Gra/Mic . (No. "z2)

(No. 14)Foyle s

391

390383200

CabinetsCaxton Wood Turnery

Co. . . . (No. 22) 291Hobbies, Ltd. . (No. 12) 659Makerimport Co. (No. 16) 414

Coils and Coil HoldersAthol Engineering Co. (No. 21) 187Falk, Stadelmann & Co.,

Ltd. . . (No. 12) 661Garnett, Whiteley &

Co. . . . (No. 22) 201lgranic Electric Co.,

Ltd. . . . (No. 72)Eric J. Lever . . (No. 21)Lindalls, Ltd. . . (No. 14)Lissen, Ltd. . . (No. 16)London & Provincial

Radio Co., Ltd. (No. 12) 648Components

Athol EngineeringCo. . (No.

.utoveyors, Ltd. (No.Bedford Radio Co. (No.Belling & Lee, Ltd. . (No.

A. Black (No.Brandes, Ltd. . (No.British L. M. Ericsson

Mfg. Co., Ltd. . (No.B.T.H. Co., Ltd. . (No.A. F. Bulgin & Co. . (No:Burne-Jones & Co.,

Ltd. . . . (No.A. H. Clackson, Ltd. (No.Will Day, T.td. . (No.Dubilier Condenser

Co. (1925), Ltd. (No.Energo Products, Ltd. (No.Falk, Stadelmann &

Co., Ltd. . (No.Fellows Magneto Co.,

Ltd. . . (No.Garnett, `.Whiteley &

Co . . . (No.General Electric Co.,

Ltd. . (No.General Radio, Ltd. . (No.Igranic Electric Co.,

Ltd. . . . (No.Goodman's (No.

Components (continued)Grafton Electric Co. (No.F. Hodgson & Sons (No.Eric J. Lever . . (No.Lissen, Ltd. (No.Omnora, Ltd. . . (No.Onoto Ink Supplies,

Ltd. . . . (No.Peranne & Co., Ltd. (No.Peto-Scott Co., Ltd. (No.Philips Lamps, Ltd. (No.Radio Instruments,

Ltd. , . . (No.K. Raymond . (No.Rotax (Motor Acces-

sories), Ltd. . . (No. 13)Sterling Telephone &

Electric Co. Ltd. . (No. 13)Ward & Goldstone,

Ltd. . . (No. 15) 305Wates Bros., Ltd. . (No. 15) 213

CondensersDubilier Condenser Co.,

Ltd. . . (No.General Electric Co.,

Ltd. . . . (No. 13)Igranic Electric Co.,

Ltd. . . (No. 12)Ormond Engineering

Co., Ltd. . . (No. t6)Telegraph Condenser

Co., Ltd. . . (No. 15)

Crystals and DetectorsEric J. LeverTungstalite, Ltd. . (No. 16)

Distant -control SystemsLissen, Ltd. . . (No. 12)Radio Communication

Co., Ltd. . . (No. 12)

EboniteAmerican Hard Rubber

Co. (Britain), Ltd. . (No.13) 103 British Ebonite Co.,12) 658 Ltd. . . (No.20) 183 Paragon Rubber Manu-22) 291 facturing Co. . (No.15) 304 Trelleborgs Ebonite16) 395 Works, Ltd. . (No.

12)22)16)

22)14)22)

19)14)

13) 3

16) 403

367282187

393

537375414

387207387

22) 385

Loud -speakersBrandes, Ltd. . (No. 21)S. G. Brown. Ltd. . (No.Cleartron Radio; Ltd. (No.Ericsson Telephones.

Ltd. . (No.Fellows Magneto Co.,

Ltd. . . (No.Fuller's United Elec-

202 tric Works, Ltd. . (No.Alfred Graham & Co. . (No.1.issen, Ltd. . . (No.Standard Telephones,

Ltd. . . . (No.Telephone Mfg. Co., Ltd.

(No. 22) 373

14) 17921) 286

22) 36720) 182

Wireless Magazine. Abvemben J926

IVedVed\.,"....".vA..e..Afte.N... r+.e.Nv"or"owif\,.-d%.Me,',.

PAGE Phones PAGE

Brandes,Thomson -Houston

Brandes, Ltd. . .

fosiN0o 22) 375J. 15)

RepairsJ. W. Miller

Sets (Crystal)Belling & Lee, Ltd. . (No. 12) 556Lissen, Ltd. (No. 16) 393

14) 183 Sets (Valve)17) 515 Belling & Lee, Ltd. . (No. 12) 556

Brandes, Ltd.tci.Burndept,. Ltd. 77

Fellows Magneto Co.,

21 2.

(No. 22)2

.De Leeuw & Co., Ltd.(c 0o r1,52990)

Peto-Scott Co., Ltd. . (No. 12) 653Radio Communication

Co., Ltd. . (No. 14) 197Radio Instruments,

2o) 89 Ltd.(1914),

(No. 12) 657A. J.

Ltd.St.evens.

(No. 15) 214Soldering Flux

Fluxite, Ltd. (No. 22) 389

TerminalsAutoveyors, Ltd. . (No. 13) 3Belling & Lee, Ltd. (No. 21) 187

J. J. Eastick & Sons . (No. 19) 86

Transformers(No. 12) 66o Brandes, Ltd. . (No. 12) 627

British Thomson -Houston Co., Ltd. . (No. 16) 317

Falk, Stadelmann &

Co , Ltd. . . (No. 12) 661Ferranti, Ltd. . . (No. 22) 387Igranic Electric Co.,

Ltd. . . . (No. 16)Portable Utilities Co.,

16) 318 Ltd. . . . (No. 14.)

Radio Instruments,Ltd. . ( No.

17) 512 Valve3Benjamin Electrical Co.

19) 85 (No. 22)British Thomson -

Houston Co., Ltd. . (No. 18) 523Cleartron Radio, Ltd. (No. 21) 263A. C. Cossor, Ltd. . (No. 19) 81Edison Swan Elec-

tric Co., Ltd. . (No. 14)Electron Co., Ltd. . (No. 22)General Electric Co.,

Ltd. . . (No. 17)Kennett 's Wireless

Stores . . (No. 18)Marconiph Co.,

Ltd. 4, eta (No. 12)Metro-VickVupplies,,Ltd.

(No. 22) 381Mullard Wireless Ser-

vice Co., Ltd.(No. 22) Cover iii

Six Sixty . . . (No. 21) 28!

17) 51816) 31522) 38011 516

2 3902

22) 37114) 20713) 312) 633

95

637

145

305

318

625

655

279-28315) 29722) 379

22) 292

12) 643

12) 65o22) 28916) 403

21) 277

(No. 17) 518

15)

407

203

291

369

193383

409

614

558

MiscellaneousBennett CollegeA. Black . .

F. Hodgson & SonsLustrolux, Ltd. .

Varlet Magnet Co.

392

. (No. 17) 421. (No. 19) 86. (No. 22) 291 Wavemeters. (No. 19) 3 Goodchild & Part-. (NO. 2 t) 285 tiers, Ltd. . (Nn. 121 661

Wireless Magazine.Novemben1926

Below the Pgrometer scale

NEW REDUCED PRICESFor 4 -volt accumulator or 3 dry cell.THE P.M.3 'General Purpose)

0'1 amp. 14/ -THE P.M.4 (Power) 0.1 amp. 18/6

For 6 -volt accumulator or 4 dry cellsTHE P.M.5 (General Purpose)

0'1 amp. 18'6THE P.M.6 (Power) DA asap. 18'6

For 2 -volt accumulator.THE P.M.I H.F. 0'1 amp. 14'.THE P. M. 1 L.F. 1 amp. 14 -THE P.M.2 (Power) 0'15 amp. 18/6These prices da not apply in Irish Free State.

j---;PrreaTi

Note the

Reading.

The pyrometercan recordtemperatures

between 7oo°C.and 2100°C.

THE LOW OPERATING TEMPERATUREOF THE WONDERFUL P.M. FILAMENT

The pyrometer can no longer claim to record theoperating temperatures of all valve filaments

The wonderful P.M. Filament has a working tem-perature that is as low as 180 degrees below thepyrometer scale.No sign of glow can be discerned from this uniquefilament with its striking economy of heat.You will appreciate the greatly increased valve lifethat can be secured with this P.M. Filament.Nothing is sacrificed.With the P.M. Filament you receive up to 51 timesthe emission of an ordinary filament.The current consumption [only one -tenth ampere]makes your accumulator charges last seven timesas long.In addition, the P.M. Filament is so tough and well -supported that itcannot be broken except by the very roughest handling.

For continuous satisfaction give your receiver valves with the wonderfulP.M. Filament and make your radio better stronger and 85% moreeconomical.

ASK YOUR RADIO DEALER FOR P.M. VALVES

British made

in a MullardBritish Factory THE -MASTER-VALVE

ADVT. THE MULLARD WIRELESS SERVICE CO., LTD., MULLARD HOUSE, DENMARA STREET, LONDON, W.C.2.

In writing to advertisers, please say you saw the advertisement in the WIRELESS MAGAZINE.

Wireless Magazine. November:1926 ENQUIRER'S COUPON, availab euntil end of month here mentioned.

Wireless Magazine. Nov e mben 1926

PLAYER'S MEDIUM NAVY CUT CIGARETTES. With or without Cork Tips.

PLAYERSNavy Cut

Tobacco Cigarettis

MANUFACTURED ONLY FROM

LLLOP Ncl. 100011.

OLD VIRGINIA TOBACCO

PRINTED IN ENGLAND BY THE. CORNWALL PRESS LTD., PARIS GARDEN, LONDON, 5.11.1, AND PUBLISHED BY CASSELL & COMPANY, LIMITED, LONDON,Sole Australian Agents, CASSELL & COMPANY, LIMITED, 210-212 Queen Street, MELBOURNE (Head Office for Australasia);

and 34 Clarence Street, Sydney.Sole A,g.ents for South Africa. CENTRAL NEWS AGPNCY, LIMITED.