WE 00 011919,11

Service inzuRoV4V REPLACEMENT

CONDENSERS AND RESISTORS

The Aerovonincludes a completevariety of replacementunits for every con-den n d resistorrequirement.

ELECTROLYTICCONDENSERS

FILTER andBY-PASS

CONDENSERBLOCKS

PAPER WOUNDCARTRIDGE

CONDENSERS

UNMOUNTEDREPLACEMENTCONDENSERS

METAL CASEDCONDENSERS

MICACONDENSERS

WIRE WOUNDCEMENT COATED

RESISTORS

CARBONRESISTORS

WIRE WOUNDRESISTORS

METALOHMGRID LEAKRESISTORS

PYROHMVitreous Enamel

RESISTORS

ADJUSTABLEPYROHM

RESISTORS

AFEW CENTSSAVED on the cost

of a replacement part isof small importancewhere an enterprisingservice man cares to es-tablish a reputation forthe work he does.

The most reliableservice men in every lo-cality demand Aerovoxproducts because theyknow Aerovox units notonly incorporate thevery best of materialsand workmanship, butare also made in exactaccordance with setmanufacturers' originalspecifications as to size,mounting arrangementsand electrical character-istics. In fact, theyknow that the voltageratings of Aerovox con-densers are in manycases even far in excessof the units they replace!

Save all trouble andexpense in making goodon poor condenser andresistor replacements.Insure every job withgenuine Aerovox re-placement parts andavoid any possible re-flection on your work.

ELECTROLYTIC REPLACEMENTCONDENSERS

Built to Outlast the Life ofAny Radio Receiver

Aerovox replacementcondensers in cardboardbox containers are pre-eminently acknowledgedthe most dependable andefficient condensers made.

Type PS condenserswith executing flanges ateobtainable in all standardcapacitiea and v o It ageratings for general servicereplacement

requirements.

,us en

Type PR units arc cam.pletely sealed in cardboardtube containers with wireleads securely riveted to

1,33 rn the condenser terminal tabs.

REPLACEMENT UNITS FOR STANDARDA.C.-D.C. MIDGET RECEIVERS

Identical in every wayto the original unitsused by manufacturersin all standard sets.Cardboard c o n to in e rtype with two heavymounting flanges.

Write for Complete 10 -Page Catalog Folderon Aerovox Prodarrs.

---BEWARE OF SUBSTITUTES FOR

AEROVOX PRODUCTS,Look for the AV' Yellow and Black

Label and Box.

NRA AEROVOX CORPORATION70 WASHINGTON STREET, BROOKLYN, N. Y.

Sales Offices in All Principal Cities

sow.'Radio Editors ofmagarines and newspapers are herebygiven permission toreprint in whole orIn part, with propercredit to the AerovorCorporation:16.ntents of ibis issue ofthe Anrovon Research

Worker.

40111?1/4),-The A e rover Rs.search Worts, Is

monthly home organof the Aemeee Car -potation. it is u

lished to bring me

the Radio Espori-molder and Engineerauthoritative, firsthand information oncondensers and resis-teeeeeforrediewerk.

VOL. 5, NO. 4 DECEMBER, 1933 eon ver tue2:4-.

Wir CAWTHE announcement in the November issue

of the RESEARCH WORKER that wehave placed a small subscription charge of50 cents a year, and 60 cents in Canada, on thispublication brings gratifying response, and wewish to take this opportunity to thank all whohave so generously co-operated with us inmaintaining this unique engineering service.

We repeat, we want to continue to make thislittle paper still more effective-and we want

it in the hands of everyone interested in ob-taining instructive, non-commercial informa-tion on the latest developments in radio. Tothis end we merely ask your co-operation withus in defraying only a part of the postage andmailing expense in sending to you 12 issues ofthe RESEARCH WORKER a year. If youhave not already sent in your subscription, doit NOW! Send 50 cents using the enclosedcoin card and your subscription will beginwith the January, 1934 issue.

the next issue of the RESEARCH WORKER,your subscription should reach us beforeJanuary 15, 1934.

Rectifier Developments During 1933By the Engineering Department, Aerovox Corporation

T" year about to close saw While there are several meth -rapid development of new ode of obtaining the required re-

types of tubes, and some improve- lectivity and sensitivity, there ismeet in the characteristics of but one known method of semi,existing tubes. New amplifiers, ing the required high d.c. vol.oscillators, de-tectors andC.CCIMAIRIROIMMOVICCOMMCCOICMCrectifiers madetheir appear-ance in profu-sion. In addi-tion manytubes werebrought onthemarket whichcombined thefunctions ofseveral previ-ous types.

TaWE

Our Many Friends . .

EXTEND BEST WISHES FOR

AT,appg lOalthag Susan and a fraaperatts New Van-

AEROVOX CORPORATIONWif1144/441.040341LECCMillnfitiM03115EARO

Cages for plate and screen supplyfrom a source of 110 volts a.c.This is the familiar process ofsmoothing out the pulses of uni-directional current by means of

inductancesand conden-sers. The pow-er supply sys-tem, therefore,is vital to theradio receiver.Hence it isworth whileto reviewwhat the year1933 (and late1 9 3 2 ) hasbrought forth

AEROVOX PRODUCTS ARE BUILT BETTERPdated In u. q. Conan.. 1993 be Amur. Ciarperetleo

to improve --or to make less ex-pensive-the power supply sys-tern.

For several years the 280 fullwave rectifier (now known as thetype 80 tube) assumed all theburdens of furnishing power tohome radio receive.. It per-formed this task well. Fortun-ately only a few manufacturersexceeded the tube designer's lim-iting figures.

In keeping with the trend ofdevelopments, however, new rec-tifiers were necessary. Late in1932 two new gaseous, and in1933 several new vacuum typerectifiers were introduced. Thesewere the types 82 and 83 (SeeTable 1) which are mercury va-por tubes with a voltage drop al-most independent of the currentdrain and of very low value com-pared to the internal resistance ofhigh vacuum rectifiers such as the280 and other rectifiers given inTable 2. While these types oftubes have been in use for sometime it may be well to reviewbriefly their theory of operation.

MERCURY VAPOR TUBESBoth high vacuum tubes and

mercury vapor tubes are highlypumped. But in the latter aglobule of mercury is placed

Mad; Mr dtdis

within the tube after the pumpingprocess. When the cathode ofthe mercury vapor tube heats upthis mercury volatilizes, i.e., be-comes vaporized, and mercurymolecules are then available for avery important and interestingphenomenon.

This phenomenon is thatknown as ionization by collision.An electron leaving the cathodein a high vacuum tube tends to gotoward the plate because the lat-ter electroffe is at a positive po-tential and the electrons are nega-tively charged, and, as is wellknown, oppositely charged bodiesattract each other. But as soonas the electron leaves the cathodethe latter becomes positivelycharged since it has lost some ofits negative charge. Further-more, all the electrons are nega-tively charged and therefore repeleach other. The net effect is theassembly of a cloud of negativeelectricity not far from the fila-ment through which electronsmust shoot to reach the plate.

This cloud, called the spacecharge, limits the number of elec-trons that actually get to theplate. The effect of this spacecharge is modulated by the vol-tages put on the grid of the tubeand, if this grid is sufficientlypositive, the cloud will he neutral.

Table I

MERCURY VAPOR RECTIFIERSTube type 62 83 865Filament voltage 2.5 5.0 2.5Filament current 3.0 3.0 5.0Tyne of cathode filament filament filamentMax. a. o. voltage per plate erne 500 500 -Max. peak inverse voltage 1400 1400 7500Max. d. c. output current, coon/moue 125 ma. 250 -Max. peak plate current 405 ma. 800 600Max. tube voltage drop (appro.) 15 15 15Tyre of rectifier Full W. Full W. Half W.

5.90.3

Mater350loll

400SO

15Half W.

Table 2HIGH VACUUM RECTIFIERS

Tube type 523 80 1-v 81 12Z3 2525 84(624)Filament voltage 5.0 5.0 6.3 7.5 12.6 25.0 6.3Filament current 3.0 2.0 0.3 1.25 0.3 0.3 0.5Type of cathode filament filament heater filament heater heater heaterMax. a. c. voltageMpperpdlat 500 350 350 700 250 125 225sae.

M.G. Ma. 250 125 50 85 60 100 -Type of rectifier Full W. Full W. Half W. Half W. Half W. Doubler Full W.

Page 2

ised and all those electrons whichdo not get caught by this positivegrid go to the plate. For this rea-son a positively charged gridcauses a high plate current. Ifthis space charge could be elim-inated, without the necessity oflosing a great number of electronsto a positive grid, the plate cur-rent of the tube would be limitedonly by the emission characteris-tics of the cathode.

Now consider a molecule ofmercury floating about in the vac-uum. An electron leaves thecathode, is attracted toward theplate and gets up more and morespeed as it approaches. If anelectron strikes a gas moleculewith sufficient force the moleculewill be disrupted, and an electronwill be lost leaving the mercurymolecule positively charged. Itis then said to be ionized. Theelectron produced will join theothers moving toward the platewhile the positively chargedmolecule, called an ion, will drift

in the tube, i.e., the cathode.Since it is positive it will neutral-ize a portion of the space charge.

The mercury vapor, then, hasas its function the elimination ofthe space charge and within afraction of a s.and after theliquid metal vaporises the spacecharge is gone and the plate cur-rent is unrestricted except by theexternal load resistance and theemission of the tube. Thus, atube the size of the 210, whichwill have a plate current of 50milliamperes at 300 volts on theplate and zero grid bias, will havea plate current of perhaps IONmilliamperes under the same con-ditions if mercury vapor at theproper pressure is admitted.

It is characteristic of mercuryvapor rectifiers that little currentflows until the plate voltagereaches a certain positive value.Therefore a steep surge of cur-rent takes place an each half cy-cle which makes the plate posi-tive. These steep surges willcause nearby circuits to oscillatejust like opening and closing anyelectrical circuit. For this reason U

IAEROV<>)(

these tubes usually have a radio -frequency choke (one millihenryor more) in the plate leads to ironout this abrupt current character-istic, The tubes are often put inshielding cans to further limit ra-dio frequency disturbances.

Since the current that can betaken from the tube may be veryhigh, precautions are taken toprotect the tube or transformer incase of short circuits; such pro-tection is provided by resistanceor reactance to limit the currentto the safe value.

As in high vacuum tubes it isdesirable to use an inductance in-put filter rather than a capacityinput type. The advantage isthat the peak currents taken fromthe tube on the positive half cy-cles will be less and thereforehigher voltages may be impressedupon the circuit without dangerof exceeding the factor of safety.

Thus the mercury vapor recti-fier is a tube for supplying quan-tities of power at excellent regu-lation to receivers needing moreenergy than high vacuum recti-fiers will supply.

VOLTAGE DOUBLERSVoltage doubling is not new.

Amateurs used it years ago withmany tiers of parallel and seriesglass jars of rectifying solutionto secure the proper voltages fortransmitters. It is strange thatits entry into the realm of radioeceivers came so late as 1933.

The 25Z5 is a voltage doublingrectifier, It consists of twocathodes, heated from a singleheater, and two plates with allconnections brought out to ter-minals. Thus the plates may beused as two half -wave tubes, eachsection furnishing power for itsown portion of the radio circuit;for example, one section power-ing the loud speaker, the othersection supplying the plates of thevarious tubes. The two platesand cathodes may be operated inparallel as a half -wave rectifierwith a 25 volt heater. This is anadvantage in universal receiverswhere some voltage must he

idmiL

Hon, kb

91 -

FIG.4

to m so SO fo0muramagaSe (I)

FIG. 2.

wasted, and this wastage mightas well be applied to some usefulpurpose.

The most interest, however, at-taches to the 25Z5 as a voltagedoubler. By this circuit 220 voltsd.c. may be secured from 110 voltsan. without the use of a powertransformer. The circuit forsuch a system is shown in Fig. 1as well as characteristics showingthe effect of increasing the inputcapacity, Fig. 2.

To obtain the highest outputvoltage a condenser type of filteris recommended. If a large capa-city is used, say 16 mfd. or morethe output voltage and the regu-lation will be improved. Sincethe peak voltage applied to the in-put condenser is relatively lowthe condensers need have onlymoderate ratings.

Ratings of Electrolytic CondensersIn the of electrolytic con-

densers ituseis naturally importantthat the condensers are not sub-jected to voltages in excess oftheir ratings. For this reason itis essential that one understandsclearly the significance of theelectrolytic condenser ratings.

In the use of electrolytic con-densers there are three principalfactors, namely, the d.c. voltageat which they are normally oper-ated, the a.c. ripple voltage acrossthe condenser, and_ thirdly, themaximum instantaneous voltageacross the condenser at any pe-riod of time, as for example, atthe moment the receiver is turnedon. These three factors are de-fined in the following manner:

D.C. OPERATING VOLT-AGE-D.C. potential as meas-ured with a potentiometer orequivalent method.

PEAK RIPPLE VOLTAGEOR A.C. COMPONENT-The peak a.c. ripple voltageis the maximum instantaneousvalue of a.c. voltage across thecondenser due to the ac. cur-rent component in the conden-ser. This can be measuredwith a cathode ray oscillographor with a vacuum tube volt-meter.

MAXIMUM SURGEVOLTAGE - This representsthe maximum potential the con-denser will withstand withoutbreakdown or permanent in-jury, for a period of five min-utes when applied to a seriescombination of the condenserand a resistance, the resistancehaving a value in Ohms, equalto "t°'''' where C is the ratedcapacity in mfd.

STANDARD VOLTAGE RATINGSD.C. Max. LAX. PB.IP. C. RIPPLE VOL.Zr% Nral CYCLIEAaVV.; 81Z11: Inn .1r.S. 6 7. 8, 9 le 12 1,18 1748350 400 30 27 25 20 15 10400 450 30 27 25 20 15 10450 525 30 27 25 20 15 10475 600 30 27 25 20 15 10500 600 30 27 25 20 15 10

Page 3

At Last!

JobbersDemanded Them !

Majestic Model 9P6 Unit

Above is a letter recently received fromone of New York's leading mail orderhouses which indicates the demand forAerovox made replacement condensers.Similar requests were received from Balti-more Radio Corp., S. Hammer Radio Co.,Radio Circular Co., and other prominentjobbers asking that we manufacture a lineof replacement condensers for standardreceivers.

In order to meet this demand we nowintroduce a new line of replacement blocks,filter and bypass units for use in variousstandard power units and receivers a fewof which are shown in the photos.

All of these condensers are identical insize and mounting arrangements to the

EROVoREPLACEMENT CONDENSERS

Are NowAvailable

original units employed by the manu-facturers. In some cases, however, theworking voltages of sections have beenincreased even beyond the manufacturersoriginal specifications wherever it wasfound necessary.

These units are the finest replacementcondensers obtainable, embodying Aero-vox construction throughout. No efforthas been spared in making them equal inevery detail to the same high standard ofdesign and workmanship of other Aerovoxproducts. They are carefully engineered

Z?:

R.F. Bypass Unit and Speaker Filter Unitfor Atwater Kent Models 37, 38, 40, 42,

46 and 52

Atwater Kent 37 and 38 Unit

and built to give long lasting service in theparticular sets for which they are designed.

Units now available are listed as follows:List Price

Majestic Block for Power Unit 9P6 $10.00Majestic Block for Power Unit 7BP6. 9.00Atwater Kent Block for Models 37 and 38 9.00Atwater Kent Speaker Filter Condenser for

Models 37. 38, 40, 42. 46 and 52 1.20Atwater Kent R.F. Bypass Condenser for

Models 37, 38, 40, 42, 46 and 52 1.50Crosley Part No. W4013 .75Crosley Part No. W4381. .70Crosley Part No. W4919. .65Crosley Part No. W5862. 1.30Crosley Part No. W5863 1.00Crosley Part No. W7753 1.00Crosley Part No. W20449 .75

These are just a few of the many units wepropose to manufacture in this line. Others willbe announced later as the demand warrants.

111 CC,NDE1,41S

CARDBOARD BOX TYPEHI -FARAD DRY ELECTROLYTIC CONDENSERS

Single Section Unit

HI. FARADDry Electrolytic Condensersin cardboard box containers shown in

the photos herewith possess exactly thesame electrical characteristics as other Hi -Farad condensers, but have been designedprimarily to reduce cost to a minimum.Their application in many radio andelectrical assemblies may often be anadvantage over the round can type units.In cases such as making up a compactblock of several units where no commonground is required and concealing thembeneath chassis, these units are especiallydesirable.

They are ideally suited for service workin repairing broken down sections of con-denser blocks used in radio receivers andpower supply units. Quick replacementscan easily be made without even removingthe inoperative condenser from the set.All that is necessary is to clip the con-nections of the particular section whichfailed in operation and attach the leadsto the terminal lugs of the new Hi -Faradcondenser.

While these condensers can be usedin practically all standard power supplycircuits, it should be remembered, how-ever, that they should not be employedin apparatus where peak voltages willexceed the condenser peak voltage of 500volts. Units for use in higher voltagecircuits may be obtained by connectingtwo or more 500 volt sections in series.

Aerovox Dry Electrolytic Condensersare not made in capacities lower than1 mfd. Capacities of less than 1 mfd.are used for bypass purposes at voltagesusually not higher than 200 volts, and forsuch service the paper condenser is farsuperior to any electrolytic. For highercapacities at 500 volts the electrolytic ischeaper than the paper condenser, butfor low voltage bypass circuits paper con-densers should always be used. The ad-vantages of the paper bypass condenserare thoroughly appreciated by all radio

500 Volts Peakengineers-that is why paper bypass con-densers are always specified for receivercircuits.

Here are the advantages of the paperbypass condenser:

1. Paper bypass condensers, such asthe Aerovox 260 and 281 series, havevery low losses and therefore giveessentially perfect filtering.

2. Paper bypass condensers have aconstant capacity throughout their life,whereas the capacity of an electrolyticwill vary depending upon the voltageat which it is operated. Engineers de-mand paper bypass condensers accuratewithin plus or minus 15 percent oftheir rated capacity. This means thatconstant capacity is absolutely es-sential, and paper condensers have aconstant capacity.

3. The Aerovox 260 and 281 seriesof paper bypass condensers are cheaperthan any electrolytic condensers of thesame capacity could be built.

ill

algL_WRLX

DI -FARAD FILTER CONDENSER

Double Section Unit

Take advantage of the Hi -Farad electro-lytic condensers where high voltage, highcapacity condensers are needed, but don'tuse any electrolytic for low voltage by-pass circuits when paper condensers aremore efficient, constant in capacity, andcheaper.

STANDARD CAPACITIES, CHARACTERISTICS, SIZES, AND LISTPRICES OF CARDBOARD BOX TYPE HI -FARAD DRY

ELECTROLYTIC CONDENSERS

Cap. of TotalMax.D.C. D.C.*

Type Sections Cap Peak Work List Code Box DimensionsNo. Mfds. Mfds. Volt. Volt. Price Word Length Width DepthP5-1 1 1 500 450 $.80 WANDA 21/2" I'/" 3,0

P5-2 2 2 500 450 .95 WARTY 21/2" %.11

P5-4 4 4 500 450 1.20 WASHY 4 1,6-" wi

P5-6 6 6 500 450 1.45 WASTE 41" A"P5-8 8 8 500 450 1.70 WATCH 4 ig" y3it

I1/411

P5-22 2-2 4 500 450 1.35 WATEL 21/2" 2jii"

P5-24 2-4 6 500 450 1.70 AVER 41" 21/2"

P5-26 2-6 8 500 450 2.00 WAXEN 4?." 2'/i"P5-28 2-8 10 500 450 2.25 WEARY 4;" 2m" 11/4"

P5-44 4-4 8 500 450 2.00 WEAVE 41'6" 2%," :NH

P5-46 4-6 10 500 450 2.25 WEDGE 411," 2,5,4^13/8t

P5-48 4-8 12 500 450 2.50 WEEDY 4 *5 21/4" 154"

P5-66 6-6 12 500 450 2.50 WEIGH 4 IV 21/4" 154"

P5-68 6-8 14 500 450 2.75 WEIRD 4A" 2'/4" 1.54"

P5-88 8-8 16 500 450 3.00 WENCH 4 A" 3" 11/4"

Note *: D.C. working voltage rating of condensers varies with circuit and loadconditions but the values given above are the average values of D.C. voltage readings,taken with D.C. voltmeter, which indicate approximately that the peak voltagesacross such points does not exceed the peak voltage rating of the condenser. Peakvoltage rating should never be exceeded (surges excepted).FOR MANUFACTURERS: The above are representative standard units carriedin stock. Special units of any desired capacity and voltage rating or combinationscan be made to manufacturers' specifications. Higher voltage units can be obtainedby series connection of units.

PRINTED IN U. S. A.