August, 1973/75cents BR08DC----- · PDF fileAugust, 1973/75cents ... down, an Indianapolis...

BR08DC-----AUG 2 O REC'OAugust, 1973/75cents

•the technical journal of the broadcast-communications industry

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www.americanradiohistory.com


.....•.•..........•••.._••...•.•...August, 1973•Volume 15,No.8

BR08DC8STThe technical journal of the broadcast-communications industry ®

• ./l.1•.•/It lllU tllfJe .••

18 A New Approach To Broadcast Facilities. Its facility burneddown, an Indianapolis station rebuilds using the modular construction technique. Bobbi Simmons.

24 Antenna And Transmission Line Protection. BE MaintenanceEditor explains sentry units, their calibration and repair. PatFinnegan.

30 Color Camera Basics. The Author describes test and comparison methods for camera selection. Joe Roizen.

34 Basic Digital Logic Review. Part two of a series designed tokeep you up-to-date on the state-of-the-art. John Lee.

40 More On IM Testing. A review of the internal operation of anIM meter and further application note on a variety of uses atthe station. Dennis Ciapura.

DepartmentsDirect Current .4Letters to the editor 8Industry News 10SBE 13Cable Engineering CE-1Engineer's Exchange 29Book Reviews 39People in the News .4SNew Products 47Classified Ads SSAd Index SS

About The Cover

BE covers the construction ofa modular broadcast station,a concept that adds newdimension to broadcast facilities.

Copyright, 1973, Howard W. Sams & Co., Inc. All Rights Reserved: Material may not be reproduced or photocopied in any form without written permission of publisher.

2

B>ITORlALRO~ALD ri. MERRELL,DirectorC.-.RLBA3COKE, Technical

PA- FINNEGAN, MaintenanceHOWARDT. HEAD, =cc RulesR03ERT A. JONES, FacilitiesW\LTER JUNG, Sclid State

ANDA-6.BOYLE, Editor al AssistantH G. RO:OSLER,Cartoonist

WEBEG. STREIT,Graphic DesignerJOE ROIZEN,\'ideo

.-.RCHERTAYLOF, CATVEDITORIALADVISORYBOARD

LES NELSON,ChairmanHowardW. Sams & Co., Indianapolis

CIRCULATIONEVELYNROGERS,Manager

ADVERTISINGE. P. LANGAN, Director

R. JACK HANCOCK, ManagerGREGGARRISON ProductionJAKE STOCKWELL,Sales

REGIONALADVERTISINGSALESOFFICESRON ROBINE-:-T

1014Wyandotte St.KansasCity, Mo. 64105

lndlanapoll<1, Indiana 46206ROYHENRY

2469E. !lath StIndianapolis, Ind.Tele: 3i7 /846-7026

New York, New Yor} 10017STANOSBORN

60 East 42nd StreetRoom 1227

New vork, N. Y. 10017212/687-7240

Las Angeles, CalllcmlaMICHAELKREITER

3600Wilshire Blvd., Suite 1510Los Angeles, California 90005

Tele: 213/383-1552

London W. C. 2, EnglandJOHN ASHCRAFT& CO.

12 Bear Streett.etcester SquareTele: 930-0525

Amsterdam C. HollandJOHN ASHCRAFT& CO.W. J. M. Sanders, Mgr.for Beneluxe & Germany

Herengracht 365Tele: C:20-240908

Toky,o, JapanINTERNATIONALMIEDIAREPRESENTATIVES,LTD.

Shiba-Kotohirncho, Minato-kuTele: 502-0656

<:IABP ~ l=l*f.;1BROADCASl ENGll'>IEERINGis publishedmonthly by lntertec Publishing Corp.,1014 Wyandotte Street, Kansas City,Missouri 64105.Telephone: 913 888-4664.

BROADCAST ENGlllllEERING is mailedfree to qualified persons engalJed inoommerclal and educational radio andtelevision broadcasting. Non-qualifiedsubscriptions in the U.S. are $6.00 oneyear, $10.0C• two years, $13.00 threeyears. Outside the USA add $1.00 peryear to cover postage. Single copy rate 75cents. Back issue rate $1.00. Adjustmentsnecessitated by subscription terminationat single cop¡ rate.

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INTERTECPUBLISHINGCORP.Subsidiary of HOWARDW. SAMS & CO., INC.

BROADCAST ENGINEERING



August, 1973 3



4 BROADCAST ENGINEERING

DIRECT C,illffiENT' -

FROM D. C'~August, 1973

By HowardT. Head

FCCRe-regulation Enters "Phase JI~~

The Commí.ssLon t a Re-.regulat.t-ori Tasi<Force (see articles Dec. 1972and March 1973 BE) has"made a·number of further minor changes inthe Rules governing radio broadcast stations and radio andtelevision auxiliar1es ~-.-·Thi~:i..spart of the Commission's continuingprogram to relax or elímfnale '[unnece"ssary and-outmoded regulations.

Rules governing AMstationsWiféensed to opérate dur~ng specifiedhours (there are a few ieft)ft.·are .reLaxed for operat.lion pastspecified time periods i -·per formanoe rules are amended to make clearthat equipment performancéli~asurements must t>etmadeat eachlicensed transmitter po~ei- o~tput level; and '1'.'Ulesgoverningrebroadcast of t.ransmí.s s í.ónsi- of rron+broadcás t' stations are simplified. The requirement for,Ccmunissio~ notifica~ion in conductingequipment or performance trests for áll classes of broadcast auxiliarystation (such as STLano.remote picJiup statiohs under Part 74 ofthe Commission's Rules) is;l eliminated.

NewCall Sign Rules-Adopterl

The Commission has adop~ecl_;p.~f'~uies governing the assignment ofnew call signs to AM,FM, arid~TVbr-oadcaat; stations. The new Rules'which are essentially proe'e,_fül'falin nature, spel1 out the practicesto be followed in requas t.Lnq hew call signs or in instances whereoutstanding licenses! or, édn'Sti-uction permits .are-transferred.

The present practice1 o'f_re·sér\ring the initial Iettefs W and K forstations east and west of¡,0t,!fe__MississAppi Rí.ve n, re~pectively, isretained. Relaxation: willl"he' permitted, however, in instanceswhere stations qualify~ng,,~fó;r~commoncall signs are across theriver from one anot.her q You :may not. reserve a call sign prior tothe issuance of a CP, qor11havea call sign effective retroactively.Only by special perm.issi.on I!lªY yourj call incl:ude the initials ofthe President of the urHtéd~States ©rJa living former President(listeners to WRMN, Elg'in~ .If.linois¡, may take this any way theywant) , or of the United Státes of' ARlerica or any Department orAgency. Finally, your co:m1:5.i:nP'ti_~:>nLs required to be in good taste.

Dual Language "Sound 'I':t.ack.sui. ~continued in P.R.

The Commission has extenoéd 'Jn experiméntal authorization for atelevision station in _Puer~oftico to operate on a dual-languagebasis, carrying the'diálogue~in the seéond language. on a companionFMstation. The usuaL .pra~t.i,a:e is to. carry t.he, Spanish languageversion on the TV aú.ráI carrier with the English language beingcarried on the FMstat.ion~ "



PICTURE ROLLS TEARING FLAGWAVING

COLOR STREAKINGHUE SHIFT SKEW ERROR

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Like 'em or not, them apples show compositeerrors in video signals which accumulateevery time you use VTRequipment. Errorscaused by changing tape geometries, varyingtape speeds, fluctuating head velocities.But how do you get rid of the bad apples?

With a standalone Delta Series TBC fromTelevision Microtime.Delta TBCsgive you broadcast quality fromevery VTR- 2-inch "quads," 1-inch helicals,3/4-inch cassettes, 112-inch EIAJ- in monochrome, or direct or heterodyne NTSCcolor.And you can get them with standalone orbuilt-in velocity error correction.Delta accessories convert V-lock VTRs toH-lock operation and add automatic skewtension correction to low cost cassette andEIAJVTR:3.Our new full line brochure, MeetThe Compatibles, describes over 20 differentmodels ... covers time baseerrors, thecauses and the solutions. Use the coupon tosend for your free copy. Or send for our ~special tape demonstration. We're available ';:¡(k,anytime to tell you how we can help solve 'time baseproblems.

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August, 1973 5



6 BROA~CAST ENGINEERING

(Continued from page 4)

This experimentation has been continuing for the past six years. Inauthorizing further experimentation, the Corrrrnissionturned downrequests of other Puerto Rican stations for similar authority,expressing the view that regular operation of this type should beconducted only after suitable changes in the Corrrrnission'sRules.A Notice of Proposed Rule Making is promised for the near future.

Various proposals have been made and are under study for the provision of a second aural signal within the regular TV channel.A number of schemes have been statisfactorily tested, includingt.he modulation of a portion of the horizontal synchronizing pulse.This second sou~d channel has been considered for various uses,including stereo sound for TV.

Short Circuits

The Commission has denied an application of a daytime-only AMstation in Geor3ia for non-directional nighttime operation with100 Watts power, pointing out that the Rules require minimumnighttime power of 500 Watts fo~ Class III stations•••The Commission has permitted a Montana TV translator, required to providenon-duplication protection to a TV broaccast station, to installremote control equipment and transmit a continuing slide announcement on the translator explaining the reason for the programblackout •.•Deciding that such a rule is unnecessary, the Commissionhas declined to require extinction of the FM stereo pilot sub-carrier for monophonic transmissions exceeding five minutes'duration •••Channeling standards have been adopted for Local Distribution Service (LDS) stations in the Community Antenna Relay band•••The Commission has awarded a quarter-million dollar researchcontract to study "Future TV Spectrum Requirements" ..•A request topermit coded transmissions in the AM broadcast band to alert FirstAid Crew members has been turned down••eThe Commission is expectedto reassign one megahertz of spectrum space in the 1\ meteramateur band te the Citizens Band for ''hobby-typeoperation•••Twoshort-spaced television stations in the middle West, required bytheir licenses to employ directional antennas for mutual protection,have proposed to substitute precise carrier offset for the directional antennas•••Land-mobile sharing of the seven UHF televisionchannels is being proposed in the Gulf of Mexico for offshoreoil drilling operations •.•The Annual Fall Symposium of the IEEEBroadcasting Group will be held in Washington, D.C. on September20-21, 1973. Sessions will include pape=s on radio and televisionbroadcasting, helical-scan VTR standards, and an address by theGeneral Counsel of the Office of Telecommunications Policy (OTP)on "Future Directions of Government Communications Policy."



Video & AudioDistributionSwitchers

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LETTERS umum•

Back To The ReservationDear Editor:

In the June issue of BroadcastEngineering the article, "The Sensuous Test Pattern," you raised aquestion of history on one of thetest patterns. Quoting, "Gone arethe days when the whole morningwas devoted to an Indian headMonoscope and a steady tone thatall the television service shops worshipped. Which brings up that eternal mystery of why the Redskin wasthere in the first place=-a query towhich no positive answer has yetbeen given.

Since it was my job in the earlydays with RCA to develop theIndian head Monoscope maybe Ican help you with the mystery. The

type 1899 was announced to thetrade in November 1938 and waslater supplemented by the 2F21 inFebruary 1946. Prior to these commercial announcements we wereworking on the development of theIconoscope for cameras along withpicture tubes. It was my function tohelp with the test equipment. Manyarguments ensued among the engineers as to where the deficiencies inthe system were occurring: in thecamera tube, in the optics, in theamplifier, the deflection or the picture tube. It was decided to evolvea standard which could be used forreference. The vehicle of the Monoscope was chosen and the now wellknown "Indian head test pattern"

was evolved; and surprisingly, hasbeen used for many years by agreat many people.

Why the "Redskin?" I had quitea collection of the then "beautifulgirls" which by today's standardsare perhaps not so beautiful, but itwas realized that style changewould occur. In the quest for sometype of half-tone material it wasdecided to use the Indian becausehis style hadn't changed over theyears and he probably would retainhis style while our "beautiful girls"would probably change-and have;thus the "Redskin."

I hope this helps with the mystery and I am flattered to see theIndian head Monoscope still receiving attention.

C. E. BurnettDivision Vice Presidentand General Manager

GE Info NeededDear Editor:

The PBS member stations onAmerican Samoa and Guam have

and CBS •.,.At NBC.·.,¡

abeand ABC ..•.. they use more BIW

TV broadcast cable'Th.emajor netwofks'preter BIW TV cable for thesame reasorís local stations do. For one thing, theyget proven-reliability. BIWwas the first TV cablemanufacturer, has more experience than anybodyelse. We're now the supplier of cable for all TVcarrieras, plus acc;:eS!Soryequipmenttor"btíier stuC:lioc;:áhleand connectorr~.!:Jirements. ~e also have both Eastanc:;West Coast tac iIities for on-the-spotsupply, service, and technical help.Write for literature. Or call.Th~ksfortuning in!

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between them seven aging G. E.television transmitters. Particularlysince the sale of much of G.E.'sVisual Communications ProductsOperation to Gates Radio Divisionof Harris-Intertype Corporation,they are having great difficulty getting certain spare parts and tubes,and the situation is reaching criticalproportions.

If anyone knows of a readysource of parts for G.E. transmitters, Model 4TT32, it would begreatly appreciated if they wouldwrite to the respective Chief Engineers at these addresses, or to me:

Ken HendersonGuam Educational TV Comm.P.O. Box 3615Agana, Guam

Dick StevensDept. of EducationKVZK-TVPago Pago, American Samoa 96799

Gene SwanzyManager, Technical Operations

Public Broadcasting ServiceWashington, D.C. 20024

Cutting Your Throat?Dear Editor:

I read with great interest thestory by Dennis Ciapura on FCCrequirements regarding proofs (BE,June '73). I would like to take thisopportunity to express some of myviews on the subject.

First of all, the quality of thesound transmitted by any radiostation should be a matter of prideto the individual station engineer. Apoor sounding station may soundthat way for a number of reasons.Station management may be unwilling to hire or pay a good engineeror to buy the necessary qualityequipment to do the job properly.Announcers may be careless intheir setting of levels, resulting inoverdriven amplifier stages and possible overmodulation. But all toooften a poor sounding station reflects an engineer who, for variousreasons, is either incompetent orjust doesn't care.

Such stations are the precise reason why the FCC must not relaxthe rules for minimum standards ofaudio performance. If anything, thestandards should be tightened.Modern broadcast equipment is

August, 1973

perfectly capable of far exceedingthe FCC technical requirements. Sowhy adhere to antiquated standardsdesigned for broadcast equipmentthirty years ago?

I personally take a dim view ofpatching equipment out of thechain from console to transmitter.If a component is in the chain, it isgoing to be contributing its share ofdistortion and noise to the finalproduct, so patching it out appearsto be only a way of cheating on theproof. If the component is a limiteror AGC amp, its gain riding function can be defeated while thecomponent remains in the chain.

Given the low quality of manymonitor speakers in use in broadcast stations today, the only way adistortion producing componentcan come to light is through theproof. So in effect, you are doingyourself a favor by not patchinganything out. I am not advocating,though, the use of cheap monitorspeakers. The quality of recordedsound today demands decent quality speaker systems for monitoringpurposes. A recording studio wouldnever even dream of using an eightdollar speaker in a ten dollar wallbaffle to monitor their finished product with a bargain basementspeaker. But this is getting awayfrom the issue.Given today's broadcast equip

ment, there is no excuse for a poorsounding station. Unfortunately, ifannual proofs were not required,there would probably be an epidemic of really abysmal-soundingradio signals on the air. The present audio standards required arefar too lenient anyway, and eliminating them entirely would be unwise.

From another standpoint, a station that allows its signal to deteriorate is cutting its own throat. Thequality of the average broadcastreceiver, especially FM receivers, isfar greater than a scant ten yearsago. The general public, especiallythe younger people, are demandinghigher quality sound that modernequipment is capable of providing.If the station cannot "put out", itis most likely going to be "tunedout" in favor of another stationproviding a high quality signal.

Robert l. MacDonald, CEGolden Strand

Broadcasting Company

Number 96 in a series of discussionsby Electro-Voice engineers

Part of the fun of reading any microphone catalogis looking at the new models designed to solve oldproblems. While most manufacturers. ourselvesincluded, put their greatest emphasis on microphonedesign. the area of accessories can often be vitallyimportant to the operating engineer.Several items soon to be seen in the E-V catalog

deserve special notice. New line matching transformers that convert 150 ohms to Hi-Z have beenintroduced. Not only are they smaller and moreconvenient (with plugs already installed, for instance)but performance has been upgraded as well, theresult of superior transformer design.

The Model 380 Mike Line Attenuator is a simpledevice (you can easily build your own from ourinformation) but when packaged with plugs installedin a small tube, the convenience of controllingpre-amp overload by simply plugging in a 380 cannotbe overlooked.

The Model 513A High-Pass Filter is an improvedversion of this useful tool. Cost has been cut 1/3, andweight by even more. Connectors are now integraland the switch has been eliminated. Getting rid ofrumble, low-frequency wind noise, and other problems is now a simple plug-in operation.

A novel answer to stage sound pickup needs is the"Mike Mouse". It's a molded Acoustifoam ™support that permits locating a microphone inconspicuously on the stage floor surface. Our originaldiscussion of stage pickup methods tell how and whythis simple bit of foam works so well. Write forSound Techniques, Vol. 3, No. l.

There are times when you may wish to use aprofessional microphone with an On-Off switch andstud mount. Enter the Model 342 Stud Adapter. Itcan be added to any 3/4" mike with XL-styleconnector. An Allen screw firmly clamps the mikewithout marring the case, and the unit can be freedfrom the stud adapter whenever desired.

Theft of microphones is a common. and seemingly-ncreasing problem. The E-V Model 340 SecurityClamp is designed to thwart the thieves. Two Allenscrews can be used to hold the mike. One squeezes ashoe that clamps the microphone firmly withoutmarring. The other can actually bite into the case ofhe mike. making unauthorized removal a majorproblem. It is generally agreed that if the microphone can't be stolen in the first 15-20 seconds, thelikelihood of loss is greatly reduced. This securityclamp should sharply cut your losses.

E-V is continually on. the lookout for new ideasfrom the field that can increase the utility and<effectivenessof our microphones. The accessories inthe back of our catalogs are our response to yourneed for greater flexibility in meeting today's soundchallenges.

For reprints of other discussions in this series,or technicaldala on any E-V product, write:

ELECTRO-VOICE,INC., Dept. 833V638 Cecil St., S;;chanan,Michigan 49107

Far More Details Circle (9) on Reply Card9



250,000Letters Needed

Broadcasters have been urged togenerate among friends more thana quarter million letters to Congressstressing the urgent need for broadcast license renewal legislation.

Mark Evans, vice president,Metromedia, Washington, D.C.,said that is "the kind of showingthat will not be ignored even inblase Washington."

Addressing a meeting of theAlaska Broadcasters Association,the chairman of the LicenseRenewal Task Force of the NationalAssociation of Broadcasters, commended broadcasters for an unprecedented job in persuading 228House members to introduce orco-sponsor such legislation andpersuading many more to support it

Evans called it "the most effective single coordinate action" in thehistory of broadcasting.

"But all of this work adds up tonothing if the bills do not becomelaw," he said. "This is the worstpossible time to relax ... We havecome this far because we haveworked hard. Let's not let the issuefail because we were not willing togive it that last ounce of effort."

Engineers SelectedSix broadcast executives have

been named to the EngineeringConference Committee of the National Association of Broadcasters.

Appointed to help plan the Con-

ference to be held in HoustonMarch 17-20 in conjunction withthe 52nd annual NAB conventionare: Chairman LeRoy A. Bellwood,director of engineering, KGTV, SanDiego, Calif.; John Bowman, manager of engineering, WMAL, Washington, D.C.; Eldon Kanago, chiefengineer, KICD, Spencer, Iowa;William B. Honeycut, director ofengineering, KDFW, Dallas, Tex.;William C. Hunter, director ofengineering, WHAS, Inc., Louisville, Ky., and Russell B. Pope,director of engineering, KHSL,Chico, Calif.Other committee members are

John R. Kennedy, vice president,operations and engineering, NBC,New York, N.Y.; Leslie S. Learned,consultant, MBS, Centerport, N.Y.;James D. Parker, staff consultant,Telecommunications, CBS Television Network, New York,N.Y.,and Royce LaVerne Pointer, director, broadcast engineering, ABC,New York, N.Y.The appointments were made by

the NAB president and the chairman of the Joint Board of Directors.

a new am Z. fm 1troacl'cast console

nao.rular for economy now.fle•i1'1e for the future!Start with the format you need now, and expand later tomeet new requirements. The Mod One console motherboard design accepts a wide selection of input· modulesand plug-in amplifier cards. 1O mixing positions, with upto 30 inputs. Modern vertical faders; silent operatingswitches; state-of-the-art circuitry.

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10For More Details Circle (10) on Reply Card




Canadians SetConvention DatesThe Central Canada Broadcasters

Association has announced thattheir annual convention will takeplace this year in Toronto at theSkyline Hotel, October 21-23.

For further convention information, we suggest you contact BertVerwey, Secretary-Treasurer, CCBAEngineering Section, c/o CKVRTV, PO Box 519, Barrie, Ontario.

Station ActivityKen Cowan of Media Horizons

signs construction agreement fornew KMEO facility. Ralph Eaton(1) and Tom Kent (r) of EatonInternational look on. Bottom picture, down in Nashville, RobertShepard (WDCN-TV), MayorBriley, and Charles Duke (WSIXTV) prepare to swap channels 2and 8.

August, 1973

Gates introduces.The CB-1200turntable

• •

::.;::~}{'~- >:-~- >::L C81200 ~ Q~

Professional in every way. Looks great,sounds great-and incorporates all thefeatures that make the difference between"good" and "best". Here are just a few.• Extremelywell-balanced hysteresissynchronous motor and low-friction dualcenter bearing. For exceptional speedaccuracy over a wide temperaturerange. And reliable, high-qualityperformance.

• Heavymachined aluminum platter,with rim drive. Permits free spinning indisengaged position for rapid cueing,and extra-fast start. Wowand flutterreduced to well below NAB standards.

• Exclusive "shear action" idler wheelhelps hold vertical and horizontalrumble to a minimum.

• Positive speed shifting allows speedchange while unit is in operation.

• Only three rotating parts in the entireturntable. Maximum reliability, minimummaintenance.

There are other reasonswhy the new Gates12-inch CB-1200 is special. Write for moreinformation on the finest broadcast turntable available.

For More Details Circle (11) on Reply Card11



Cox Broadcasting Deals For KFICox Broadcasting Corporation

has announced it had consummatedthe purchase of AM Radio StationKFI, Los Angeles, for $15.1 millioncash. In making the announcement,J. Leonard Reinsch, president ofCBC, said papers formally transferring ownership of KFI to CoxBroadcasting Corporation were

signed in Los Angeles.CBC's acquisition of KFI, one of

the nation's pioneer radio stations,had been approved by the FederalCommunications Commission onApril 18, 1973. An agreementunder which Cox Broadcastingwould acquire the operating assetsof KFI from the trustees of the

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Earle C. Anthony Trust, was announced in July, 1972KFI, a 50,000-W att, clear

channel facility, serves an audienceof 10 million people in the LosAngeles metropolitan area. In 1972,the station celebrated 50 years ofbroadcasting.The acquisition of KFI brings to

five the number of AM radio stations owned and operated byAtlanta-based Cox BroadcastingCorporation. The Company alsooperates four FM radio stations,along with five VHF televisionstations serving Atlanta, Dayton,Charlotte, Pittsburgh, SanFrancisco-Oakland and Miami.

Emmy Award ToCMX Systems

The Emmy, the most prestigioushonor conferred by the NationalAcademy of Television Arts andSciences, was awarded to CMXSystems for its development ofcomputer controlled video tapeediting and assembly systems.A CBS/Memorex company, CMX

developed the technical concept andmanufactures the electronic, highlyautomated editing systems for theprocessing of video tape programs.CMX produces on-line and off

line editing and assembly systems.On-line systems interface directlywith quadruplex video taperecorders (VTR), permitting videotape editing decisions and programsassembly to be accomplished simultaneously. Off-line systems allowediting decision to be made independently, with final programassembly being performed automatically during hours of low VTRdemand.

For Latest NewsSee

Direct Current page 4




SBE Insurance Program

Several years ago our Board ofDirectors approved a Group Insurance Program for SBE members.The first plan introduced was theLife Insurance Plan, which nowoffers member coverage up to$50,000.00, with lesser amounts fordependents. For the past policyyear ending October 1, 1972, eligible insured members received a 40percent dividend credit on theirspring contribution notices. Thereis now over one million dollars ofmember and dependent coverage inforce.

Last year, the Program was expanded to include a host of accident and sickness plans to suit theindividual insurance needs of members. These include a DisabilityIncome Plan to protect a member'swages during period of disabilitydue to sickness or accident; a Hos-

DeadlineReminder

For ChaptersReports of SBE chapter meetings

and announcements of' futureevents will be published in thesepages monthly. It is important thatchapters send information on meetings and other news as promptly aspossible. Include photographswhenever available; preferred photosize is 8 x 10 but smaller sizes arealso usable.The monthly deadline for submit

ting copy is the 25th of the 2ndmonth preceding the month of publication. For example, the date bywhich copy must be received by theSBE editor for the October 1973issue is August 25th; for the November 1973 issue, the deadline isSeptember 25th, and so on.

Letters to the SBE Editor forpublication in the Journal are welcome.

Send all material for publicationto: SBE Editor, Joseph A. Risse,;P.O. Box 131, Dunmore, Pa. 18512.

August, 1973

pital Dollars Plan providing dailycash payments during periods ofhospital confinements; a MajorHospital-Nurse-Surgical Plan withbenefits up to a maximum of$15,000.00 and a $200,000.00 HighLimit Accidental Death and Dismemberment Plan which will haveall benefits increased by 15 percenton October 15, 1973, without acorresponding increase in premium.The success of the Program de

pends upon the interest and activesupport of our membership. WhileSBE has made the Program available to its members, no expense isincurred by the Society.

If you wish to have a brochuredescribing the Program, please contact the Administrator, SBE GroupInsurance Program, 1707 L Street,N.W., Suite 800, Washington, D.C.20036 (Tel: 202-296-8030).

Annual RebateReminders

Here are some reminders fromSBE Headquarters: Chapters: Besure to apply for annual rebatesfrom SBE headquarters. A rebateof up to $100 annually is possiblebased on membership attendancefor the preceding year. To obtainthis rebate it is necessary to complete the Annual Attendance Report Form which may be obtainedfrom Virginia Doss, SBE, P.O. Box88123, Indianapolis, Ind. 46208.Virginia would also like chapters toremind members that attractiveSBE tie tacks are available fromher for $3.50 (members only).

When corresponding with SBE(Continued on page 14)

New SBE Chapters FormingThe following areas represent lo

cations for possible future chapters.Information on any planned organizational or technical meetings maybe obtained from the individuallisted as the "contact" in each case.Anyone interested in chapter activities in other locations may contactVirginia Doss, Assistant SecretaryTreasurer, SBE, P.O. Box 88123,Indianapolis, Ind. 46208, or atWRTV, 1330 N. Meridian, India-

LOCATION

napolis. In some cases, assistancefrom SBE national officers anddirectors may be available. Contactany officer or director, or SBEPresident James C. Wulliman, atWTMJ, 720 East Capitol Drive,Milwaukee, Wisconsin. Those involved in the development of newchapters should also keep the SBEJournal Editor posted so that thiswork can be aided by promotion inthe Journal.

CONTACTTucson, Ariz.: H. J. Bart Paine, telephone 882-6644,

or Chuck Deen, KOOL-TV, 511 WestAdams, Phoenix, Arizona, telephone271-2345.

Miami, Fla.: John Blattner, 11001 N. Kendall Dr.,Apt. A107, Miami 33156.

St. Louis, Mo.: Arthur H. Rounds, 1321 Aspen Drive,Florissant, Mo. 63031.

Puerto Rico: Bob Beurket, Asst. Chief Engineer,WRIK-TV, Ponce/San Juan, PuertoRico, telephone 809-724-7575.

San Francisco, Robert Daines, CBS Laboratories, OneCalifornia: Embarcadero Center, San Francisco,

Calif. 94111.

13



-------SOC1f.T'f Qjl GFIQAOCASTf.NQ!Nf.l!FIB.INCP o eo• 1u¡,a3 ,••.,.••.••,.•••.•.,•.•.,.•••• •eaoa

(Continued from page 13)

about your membership includeyour membership number. Submitchange of address promptly. If youare not receiving Broadcast Engineering magazine, provided as acourtesy by the publisher to SBEmembers at no cost, notify VirginiaDoss. Letters to the Editor, ChapterNews, articles, and other information for publication should be sentto SBE Editor, Joe Risse, P.O. Box131, Dunmore, Pa. 18512. Articlesneed not be professionally writtenbut they should be technically informative-diagrams can be handdrawn, but legible and accurate.

Chapter NewsChapter 1 - Binghamton, N.Y.Chairman: Larry Taylor,WENY-AM-FMMark Twain Hotel,Elmira, N. Y. ~4902The chapter held its annual pic

nic on June 12th at the NewtownBattlefield Reservation, in the covered pavaillion. The chapter provided members, families and guestswith hamburgers, hot dogs, beer,pop, paper plates and plasticware.

The next meeting will be in September. The preceding meeting washeld jointly with Chapter 2 (Northeastern Pennsylvania) and Chapter22 (Central New York). Scenestaken at that meeting are shown inthis issue of the Journal.

Chapter 2 - Northeastern Pa.Chairman: Paul Evanosky,WVIA-AM-FMOld Boston Road,Avoca, Pa. 18640Charles Hallinan, a former SBE

president, was the guest speaker atthe June 4th meeting at the studiosof WVIA-FM-TV. Hallinan, whohas made himself available formeetings of other chapters in thisregion described broadcast equipment manufactured by his employer, CCA Electronics. Several itemsof equipment were also on exhibition for close examination by members and guests. Included were anew RF amplifier and a modulationmonitor. A question-and-answersession was included. While thenext official meeting was scheduledfor September, members were invited as in previous years to attenda clambake scheduled for sometimein July with the Luzerne CountyRadio-TV Service Technician Association, to be held at the IremTemple Country Club, Dallas, Pa.

After-Dinner Scene at Joint Meeting of Chapters 1, 2, and 22, held at the OwegoTreadway Inn, Owego, N.Y. Dinner preceded talk by guest speaker Otis Hanson,Chief of Existing Facilities, FCC, Washington, D.C. Broadcast Engineers fromthe Binghamton, N.Y., Syracuse, N.Y., and Scranton-Wilkes Barre, Pa. areaswere wel I represented.

14

Chapter 9 - Phoenix, Ariz.Chairman: Charles Deen,KOOL-TV511 W. Adams,Phoenix, Arizona 85003Delaun Rester, vice chairman,

presided over the April 12th meeting at Shakey's Pizza Parlor; thehost was Dalis Electronics. Reportson the NAB Convention and SBEAnnual meeting were provided byCliff Stephens, KTAR; Al Hillstrom, KOOL; and Roger Johnson,KOY. On May 18th chaired themeeting at the College of Medicine,University of Arizona, at which EdFitzgerald and Dick Johnson ofSparta Electronics described Sparta's new FM exciter, stereo generator, and FM transmitter. Membersfrom the Tucson area scheduled aspecial get-together for May 24th todiscuss a possible chapter forTucson.

Chapter 15 - New York, N. Y.Chairman: John M. Lyons,WRRL AM 41-30 58th St.,Woodside, N. Y.Bernard Wise, president of CCA

Electronics, was the guest speakerat the June 14th meeting, held atWQRX Presentation Theater, 229W. 43rd St.; his talk was The Stateof the Art of Radio, Television, andThe Industry in General, centeringon new equipment recently introduced and ways of working aroundequipment you presently have.Those interested in attending futurechapter meetings, which are held inthe New York Times Building, andpreceded by dinner for those interested in the cafeteria, may contactchairman John M. Lyons at 212-335-1600, or Art Silver at GatesRadio, 212-889-0790, or secretaryBob Woerner, WNEW TV, 212-535-1000. The next meeting isscheduled for September 9th.

Chapter 16 - Seattle, Wash.Chairman: John Maxson,KETO-FM17425 63rd Pl., S.E.,Issaquah, Wash. 98027The luncheon meeting on June

13th at the Norselander Restaurantwas a feature program on the TVpickup of the Apollo 17 Recoverysplashdown of last December, pro-




vided by NMT Manager Stan Carlson who told about KING-TV'sNorthwest Mobile Television truck,equipment, and personnel, all ofwhich were aboard the TICONDEROGA carrier with NBC-TV. BudJohnson, Technical Director, wasnominated but lost out for anEmmy Award for his work. BobDietsch, of the local FCC office,presented his monthly report oncommission activities.

Guest Speaker at recent Joint Meetingof Chapters 1, 2, and 22, held atOwego, N.Y., was guest speaker, OtisHanson, Chief of Existing Facilities,Federal Communications Commission.Hanson Spoke on the internal workings of the FCC and provided a lookat the why of past rules and regulations and discussed what 'to expectfrom the future.

Chapter 18 - Philadelphia, Pa.Chairman: Jack Jones,WCAU-TVCity Line and Monument Aves.Philadelphia, Pa. 19131

Peirce Phelps discussed and demonstrated the Consolidated VideoSystems Time Base Corrector at aJune 25th meeting at Williamson'sRestaurant. The meeting was preceded by a refreshment hour anddinner, all of which were handledby Ed Kushner of WCAU-TV. Information on future meetings maype obtained by phoning (215)~39-7000 and speaking either withJack Jones or Ed Kushner. Scheduled dates for Fall meetings areSeptember 24, October 22, andNovember 26.

August, 1973

Chapter 22 - Central New YorkChairman: Hugh Cleland,WCNY TV/FM506 Old Liverpool Rd.,Liverpool, N. Y. 13088On June 12th, dinner at the

Dinkier Motor Inn preceded thetechnical session at WSYR wheretheir new Vital production and onair switching systems were demonstrated and explained. Eric Kingrepresented Vital Industries. TheWSYR-TV production switcher features drift-free circuitry, enablingthree mix-effects systems in a control panel no larger than mostsingle mix-effects switchers.The previous chapter meeting

was the one for which Chapter 2was the host, held in Binghamton.

Chapter 25 - Indianapolis, Ind.Chairman: Joe Missick,WISH-TV1950 N. Meridian St.,Indianapolis, Ind. 46202

Chairman Missick presided atthe April meeting, held at the Holiday Inn, Northwest, which wasmainly in honor of three retirees:Benny Weimer of WISH-TV; HalTrosper, WIRE, and Martin Williams, WFMS. Plaques were presented to these veterans for theircontributions to broadcasting. TheMay meeting, at the Television Department of the Indiana StateUniversity in Terra Haute, includeda tour of the facility by BuddyKline, chief engineer.

Chapter 30 - South Bend IElkhart, Ind.Chairman: Chris Frederick,WJVASouth Bend, Ind. 46624The chapter met on May 17th at

the CTS plant in Elkhart. Includedwas a tour of the plant, conductedby Jerry Ash and Max Long, bothof CTS. The next meeting is scheduled for September. Members andthose on the mailing list will receiveadvance notice. Others interestedmay contact Mark A. Carey, chapter secretary-treasurer, at WTRC,Elkhart.

The SBE now has one moreactive chapter, in Tucson, Arizona,as a result, at least partially, ofenthusiasm and support generatedby officers and other members of




Chapter 9, Phoenix. At the regularmeeting of the Phoenix chapter onMay 18th, H. J. Bart Paine calledfor an opinion of those present onforming a Tucson chapter. Unanimity resulted in the first regularmeeting of the Tucson group onMay 25, 1973. Bart Paine andCharlie Glickman are acting as theChairman and Secretary, Pro Tempore, respectively. Voluntary committees of membership and elections were voiced by Bob Hendrickson, Armand Sperduti, CharlieGlickman, and Rich Heatley. Theassistance and direction of thePhoenix chapter, namely ChuckDeen and Roger Johnson were citedas being especially valuable.

Future meetings of the Tucsonchapter will be reported in thelistings of other chapter meetings.

Use Your JournalThrough these pages, provided by

special arrangement with the publisher of Broadcast Engineeringmagazine, members of the Societyof Broadcast Engineers may nowcommunicate with each other; SBEheadquarters can pass along infor-

mation to the general membership;SBE chapters can report and announce information concerningtheir meetings or other activities;and we can air issues of vital concern to all of us who are employed

one way or another in the field ofbroadcast engineering.

A means of communication isvital to any organization. Let's utilize this unusual opportunity whichis now available.

The first meeting of the Tucson, Arizona chapter. Front Row, left,George Wickle, Armond Sperduti, Richard Heatly, H. J. Paine. SecondRow, left, Dick Ward, Bob Hendrickson, Tom Inman. Third Row, JohnChitwood, Roy Holsdaw, Bob Collett, Roger Johnson. Last Row, GeneKuklin, Bob Wilson, Charlie Glicksman, Kevin Windren, Tony Novak.

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For complete information, writeSpindler & Sauppé, 13034 Saticoy St.,North Hollywood, Calif. 91605;phone (213)764-1800.

16

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NAB CommitteeTo Review

TV Code FeesRobert F. Wright, president,

WTOK-TV, Meridian, Miss., andchairman of the Television Board ofDirectors of the National Association of Broadcasters, has appointedcommittees to review the fee structure of TV Code subscribers and todevelop methods of informing thepublic about the effect pay television will have on free TV.

Named to the Television CodeDues Committee were Peter Storer,executive vice president, StorerBroadcasting, Miami Beach, Fla.,chairman; Leslie G. Arries, Jr., vicepresident and general manager,WBEN-TV, Buffalo, N.Y.; WalterBartlett, senior vice president, Television, Aveo Broadcasting, Cincinnati, Ohio; George Comte, generalmanager, WTMJ-TV, Milwaukee,Wis.; Richard W. Jencks, vicepresident, Washington, CBS, andRay Johnson, executive vice president and general manager, KMEDTV, Medford, Ore.The committee on pay-TV con

sists of Willard E. Walbridge, senior executive vice president for corporate affairs, Capital Cities Broadcasting, Houston, Tex., chairman;Eugene S. Cowen, vice president,Washington, ABC; George Gray,vice president, Washington, AvcoBroadcasting; Richard W. Jencks,vice president, Washington, CBS;Peter Kenney, vice president,Washington, NBC; Dale G. Moore,president, KGVO-TV, Missoula,Mont., and Fred Weber, executivevice president, Rust Craft Broadcasting, New York, N.Y.

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Rebuilding WFMS, or ..

A new approachto broadcast facilities

The happy conclusion that yousee pictured on Broadcast Englnering's cover this month occurredwhen WFMS moved into its new,fully equipped radio center on May9, 1973. Only 14 weeks after thetragedy, WFMS was at home in apermanent new broadcasting facility, custom designed and built forthem. How was such a speedyrecovery possible?

Ron Voss, station manager ofWFMS, began the story with thehectic weekend following the fire.When they could get back into theruins, staff members salvaged what

By Bobbi Simmons

The clock in the production studio stopped at 1:53 p.m., then afire of unknown origin silencedWFMS, the oldest commercial FMstation in Indianapolis, Indiana. Itwas Friday, February 2, 1973.

At 10:49 p.m. on Sunday, just 57hours after the fire, WFMS returned to the air, with full powerand in stereo, with the "Good Life"sound of music. Working conditions were very primitive, but atleast they were on the air.

Fig. 1 Station Manager Ron Voss and Program Rick Bernard get operationsunderway in their new WFMS facility. (Photos by McGuire Studio, Indianapolis)

18

records and files they could. Amotorcade formed to take everything to the program director'sapartment, a temporary office. Atthat evening's staff meeting, amidsomber talk, a staff resolve wasformed to get back into operationas fast as possible. They agreed:"We're a team. Let's get WFMSback on the air!" That dedication,and the help they got from theirparent company and some suppliers, made a fast comeback areality.

On Saturday after the fire, corporate management people from Susquehanna Broadcasting Company,owner of WFMS, and engineersconverged on Indianapolis. Newequipment was rush ordered. Susquehanna stations in Ohio andPennsylvania began reproducing theWFMS music tape library. Manyoffers of assistance, such as loanedoffice furniture, came in duringthat weekend.

On Saturday, two portable buildings, each about 8 x 10 feet, wereplaced next to the tower. Sunday, anew transmitter arrived from NewJersey. Voss flew to Chicago to pickup a new audio console. RickBernard, program director, retapedcommercials and production materials at Susquehanna's Cincinnatistation. Fifty-seven hours after thefire, WFMS came alive again.

Getting Back To NormalHow to get back into a perma

nent operating facility, however, remained a big problem for RonVoss. He wanted to get out of thelittle portable buildings as soon aspossible. Sounds of demolishing therubble went right through thetemporary studio's thin walls. Anearby train track didn't help mucheither. Months on the air with thatkind of sound pollution wouldn't domuch to get the station's new soundof the "Good Life" off the ground.

Of course, one of Voss's alternatives was to rebuild a conventionalbuilding on the same site. Any




I

II -

on-site construction begun duringan Indiana February. however,would have an uncertain completion date at best.

As another alternative, Yoss considered movable offices and othermobile home-type structures thatwould be available immediately. AllWFMS would have to do is movethem in . . . . and convert theminto a radio station. That job wouldbe difficult. particularly in terms ofacoustics and soundproofing. Andtheir appearance wasn't satisfactoryto Yoss for a permanent home forWFMS. He decided against movable buildings; but he didn't wantto wait months for on-sit e construction, either. In talking tobuilding contractors in Indianapolis. he found a third constructionalternative that sounded good.

Structures of America, in Elkhart. Indiana. makes custom-builtmodular commercial buildings. Thereason SAi looked so interesting toYoss is that their constructionmethods are identical to methodsused in on-site conventional construction. but SAI produces a new,custom-designed building in only 6to 8 weeks from its order.

A radio station, of course, hasspecial construction needs in termsof acoustics and electrical wiring

Fig. 2 As you can see inthe detail of this picture,the WFMS structure waspre-built inside the SAifactory before beinghauled to the new site.Note that the doors arealready hung, and eventhe thermostat is wiredin.

A COMPARISON~OF CONSTRl.!ICTION METHODS-iH ~ al

{based on an investigation of costs in Jndi~napolis, Indiana,·- in February 1973) ·

Building method~ CostConventional -$33 per sq. ft.

FlexibillityCompletelyversarnl -on-site

construction

c$25 per sq. ft. Complet'81y_versatile

Steel b_uildings

Have to'berernodeléd 'forsoundpr'9ofing

Temporaryt5uildings

$15-$16 persq. ft.

SAi commercialbuildings

Comple!í!IY.versatile

August, 1973

Time necessaryfor completionAt least threemonths

7 to 8 weeks forsteel deliveryplus 60 to 90days for finish

4 to 5 weeks fordelivery plusIn-field alteration

6 to 8 weeks

19



Fig. 3 Even the modern decor of the new.obbv lends itself to the new look of WFMSRadic . Secretary Rhonda Downs settles inand DJ Rob McConnell relaxes before hisshow.

~ •..-Fig. 4 Chief Engineer Rick Martindoubles at the new board.

ManagementHighlights

In an effort to serve the decision-making team, this magazine has covered rnany., majorfacility design changes. We'vegone from renting, to completefacility design, and on to eventhe use of mobile homes. Recent Iy, we found a new approach: the modular broadcastbuilding. We think you'll fir.dthis building concept interesting.

20

that no mobile structure can fillwithout extensive remodeling. Anysuch special feature, however, canbe built into a modular buildingright at the factory, just as it can inconventional construction.

Since SAI buildings are built inthe factory, delays of weather andwork crew holdups don't affectcompletion of the building. Thisapproach extends the constructionseason to a full 12 months. And theunits can be built to assemble inany configuration, even to make atwo-story building.

Hold EverythingAt first, Voss was skeptical. "The

idea of modular construction meantless than optimum constructionmethods to me, based on what Iknew about other modular companies," Voss said. "I was afraid itwould compromise the quality Iwanted in a permanent facility. ButErnie's sales story did sound convincing, so I decided at least tocheck it out."

Voss visited two other modularradio stations which SAI had built- WMEE in Fort Wayne, Indiana,and WSJM in St. Joseph, Michigan.I-le saw the custom-designed construction SAi had done for them,then went to SAI's plant in Elkhart

to see how they did it.He learned that SAI doesn't

make units of typical residentialtype construction, and then callthem offices. They can't because ofbuilding codes. "Commercial building codes are much more strictthan residential codes, especially inIndiana," according to Lou Britt,SAI's marketing vice president."The quality of modular construction becomes apparent just in comparing module weight. A residentialunit will weigh about 10,000pounds; an SAi commercial unit ofthe same size (about 12 x 48 feet)weighs between 22,000 and 24,000pounds." Britt said.

Because these buildings are allcustom designed, the customer getsa true broadcast facility. WFMS isa good example. They looked at asmall rough sketch of WFMS'sspace needs. Then they drew up aset of plans to meet that layout andinclude all the special acousticaland electrical requirements.

A New Look, TooVoss chose the kind of look he

wanted the building to have. Hehad a choice of any number offactory-applied wood or prefabricated masonry sidings to complement SAi's bronze frame and




••••••.) ~

Fig. 5 Steve McNeal, amid a completely newarray of Control Room equipment, renewsthe WFMS "Good Life" sound approach toprogramming.

tinted windows. He found out thatthe units could even be bricked onthe site. if he wanted brick. Hechose a contemporary rough-sawngrooved cedar siding, stainedbrown. and panels of Sa n spr ayfaggregate stone siding for accent. Amansard roof of shake shingles wasput on the WFMS building afterthe units were set in place to addanother design element to its contemporary lines. Ins id e, Hom aso tedecking. made of 100 percent recycled wood fiber, was chosen in1-718" thickness to soundproof thestudios effectively.

Four weeks after Yoss told ErnieDallman to order the SAI building,it was time for a party. The occasion: watching a gigantic cranehoist the six SAI units into place.

Yoss summed up his decision togo with modular building. We didconsider every alternative carefully.SAi could give us exactly what we

August, 1973

needed in building design .... andin a very short time. And we'vesaved about 20 percent over thecost of building the same thing byconventional means, not to mentionthe time involved.

Can there be anything goodabout a fire? Certainly not by design. but WFMS does have a new,modern radio center. And the staffwas able to put their good humorto work to make the most of theirdifficulties in the meantime. Thetire became a sales promotion, too,on the air: "Too hot to cool down.""WFMS is carrying a torch forIndy." "Stereo 95.S has crossedburning bridges to bring you thesound of the Good Life."

WFMS also ran a fire-preventionpromotion. Listeners were encouraged to write in for a pamphlet onpreventing fires.

The WFMS staff gained something personal from the fire, too.They know how to be humble, if

they didn't before the fire. Andthey learned how to be grateful-inthis case, to e.ach other, the company, and everyone who helpedthem get W FM S back togetheragain. Their cooperation and hardwork to resume operations are indicative of the staffs dedication tothe business of broadcasting. Afterall, as Rick Bernard said in hispost-fire commentary, "Whenyou're hot, you're hot!" O

Editor's Note: While BE is in noposition to pass judgement on facility construction detail, we do believe the modular construction concept will add an interesting alternative for the decision-making team.More than half of our readers areoperating today from facilities thatwere not designed for their currenttasks. Because of this, these facilities may always get in the way ofprogress and profit, not to mentionstation electronics.

21



The quality thatTAYproducesis like thecamera it uses.Trans-American Video does greatwork. They really have an eye forvideo tape. In fact, they're quite aunique video facilities company.When it started in business over ayear ago, it ordered nine of the firstFernseh cameras sold in the U.S.TAV used those cameras to coverthe U.S.-Russia track meet andthen proceeded to become theworld's largest independent mobilecolor video tape facilities company.Their current credits include NFLMonday Night Football, YoungDr. Kildare series, Burt Bacharachin Shangri-La special, DukeEllington ... We Love You Madlyspecial, and Frankenstein, Parts Iand 11feature.Today, TAV has over $8 million

worth of equipment. And here'swhat they have to say aboutFernseh cameras:"It took only a short training

period for our operators to learnto use the cameras, and for thecameras to establish themselves asquality pieces of equipment."

"The Fernseh cameras are easyto set up and strike. Once they'reregistered, they're extremely stable.A video operator does not have tocontinually ride the pictures."There's a lot more we can tell you

about the family of Fernsehcameras. Interchangeable modules.Small diameter cabling.Performance specifications, etc.For more detailed information,contact your local Fernseh divisionrepresentative at one of theoffices listed below.Chicago Hdqts. (312) 681 -5000Houston (713) 681-8461Los Angeles (213) 649-4330New York (516) 921-9000Ramsey, N.J. (201) 825-1550San Francisco (415) 583-9470

Robert BoschCorporationFernsehD. . . s-cIYISIOn ~ t~fv~i~~s



Antenna andtransmission line

By Pat FinneganBE Maintenance Editor

Coaxial transmission lines andantennas used in television and FMservice, are important and expensive investments. This is the finallink between the station and itsaudience. What makes the problemof greater significance is the factthat the major part of this equipment is in a rather inaccessiblelocation and can't easily be inspected on a daily basis.

There is one unfailing barometerof pending problems up the lineand antenna. and this is the reflected power back down the line -the YSWR. It only makes sense,then. to use this reflected power to

protectionprotect the line and antenna system.The protection unit is a relatively

simple device that is manufacturedand sold under several trade names.This sentry unit monitors theYSWR at the sending end of theline. If the YSWR rises above avalue which has been preset on theunit, it will turn the transmitter offautomatically. Not only that, but italso will not allow the transmitterto be returned to the air until thefault has been corrected, or the unititself disabled.

The heart of this sentry unit is ameter relay. Voltage derived fromthe reflected power by a diode ismeasured by the meter which is aDC movement. But contained within the meter is a relay that is actu-

Management HighlightsA VSWR meter or sentry unit are transmission line and antenna

quality indicator devices. They can indicate developing problems and- as in the case of the sentry unit - protect transmitting equipment.The decision making team should have this in mind the next timetransmission line and transmitter problems or changes are discussed.

,_,,\,CCA~~' .:...VSWR Wa-rc.hdo~

L·The sentry unit should be a vital

protection unit in your system. Thisunit, called the "Watchdog", is shownin the rack at WLBC.

24

ated by the meter hand itself as itpasses a preset trip point (or themeter hand may operate photoresistors which in turn operate therelay). When the internal relay contacts operate, these usually operatean external relay. The external relay may have higher rated contactsthan that in the meter and thesecontacts of the external relay, then,open the transmitter interlock circuit.

To assist getting the transmitteron in the morning, there is usuallya delay circuit or a time delay relayin the unit, set for 1 or 2 seconds.This and the other few componentsof the unit are generally panelmounted for mounting in a rack.Three inputs to the sentry unit

include: 120 YAC for internal use,DC sample voltage from the samplediode, and connection to the transmitter interlock circuits.

VSWR is a ratio between theforward and reflected power, so thesentry unit must be calibrated if itis to read VSWR correctly. Duringthe calibration process, the transmitter forward power and the transmitter power raise/lower controls

PROTECT!ON UNIT

120\/ ACffOR INTERNAL USEl

CAL. POT.D. C. SAMPLE FROMDI ODE IN REFLECTEDPOWERPOSITl ON ATDIRECTIONALCOUPLER

EXTERNALRELAY

Fig. 1 Block diagram of the protectionunit, showing the external connections.

.__~~~~~~~-+-roTRANSMITTERINTERLOCKCIRCUITS




We'd like to sell youa product thatisn't working.

Color television took years to perfect. Butthe potential was there.

We have a product with great potential.Perhaps you've heard our name, but not knownwhat we do. We're the National Alliance ofBusinessmen. We're in business to help America'sdisadvantaged citizens ..Products of the ghetto,poverty, poor education and life's bad breaks.Our purpose is to make the American systemwork, by seeing that everyone who wants to workcan become a fully participating citizen.

If you read on, you'll see why 30,000NAB participating companies have found itgood business to employ and train a milliondisadvantaged persons. Why thousands oftalented executives have been loaned to us byAmerica's leading corporations.

We were formed by presidential mandate toserve as a catalyst between government andbusiness. Business provides the jobs and government finds the persons to be hired and trained.Most companies pay the training cost themselves.Companies that cannot afford to take on thetask of employing and training the hard-coreunemployed can be given financial support bythe government. We think this partnershipbetween business and government is a good wayfor our society to deal with its problems.

We have programs that deal with thehard-core unemployed. Hiring, training and

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With 500 full-time loaned executivesmanning offices in 164 cities, we are fullycommitted to helping the nation solve one of itsmost pressing problems.

As President Nixon has said:"The National Alliance of Businessmen has displayed a remarkable capability to mobilize theAmerican business community in response to anational problem."

We have a product to sell. And programsthat make it easy to buy. Contact the NationalAlliance of Businessmen. Help us get our productand our country working.

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August, 1973 25



are used to simulate high VSWRconditions.

Turn on the transmitter andmake sure it is loaded with thenormal line and antenna. Adjust itspower output to 100 percent on itsregular power meter. Now, at thesentry unit, rotate its trip control tothe far right, which is about 120percent. This will allow calibrationwithout the unit tripping the transmitter off. Connect the input leadof the sentry to the Forward Powerdiode, after disconnecting the transmitter meter lead from the diode.The sentry should now read thetransmitter power output, but probably not 100 percent. Turn the calibration potentiometer on the unituntil the meter reads 100 percent.The unit is now calibrated for 100percent power forward.

To calibrate the trip point, reduce the transmitter power outputby its own controls until the meteron the sentry reads about 1.1VSWR. Now rotate the trip adjustment pointer until it is setting at1.3 VSWR. Slowly increase thetransmitter power until the unittrips the transmitter off. Try thistwo or three times. Each time theunit trips, you must reduce thepower below the trip point and thenpush the reset button on the unit.

Meters often are not exact, so thetrip may be slightly different thanthe setting. For example, the trippoint is set at 1.3, but it actuallytrips at 1.35 VSWR. Take this intoaccount when setting the final trippoint. For sentry use, you can set itto trip at any figure you desire, but1.3 is a typical setting. The higherthe power of your transmitter andthe closer to ratings the line andantenna are working, the more youmay desire to set this trip pointmuch lower.The unit is now calibrated, so

lock the calibrating controls andrestore the connections to thediodes at the coupler. The ForwardDiode will now feed the regularpower meter on the transmitter,while the reflected power diode willfeed the sentry unit. The meter onthe sentry unit will now be indicating the actual VSWR at the sending end of the line.Only minimal maintenance is re

quired on the unit, and this isbasically inspection during the nor-

26

1()()%

TRANSMITTERDIRECTIONAL COUPLER

I I , • ANTENNA

(A)

TRANSMITTER 1()(1"'

IBl

F. R.-TRANSMITTER1% POWER

R

ICl

I J;" =;J, I ~· ANTENNA

TRANSMITTERPOWER METER

lDl

Fig. 2 Calibration procedure and normal connections: (A) Adjust transmitteroutput to 100 percent; (B) Set trip control to 120 percent and adjust Cal pot for100 percent. Lock Cal pot; (C) Reduce transmitter VSWR to 1.1 and set trip for1.3. Increase power until trip occurs. (O) Normal operation: Forward diode feedstransmitter power meter; reflected diode feeds sentry and measures VSWR.

mal transmitter inspections, andsome checkout out maintenanceduring "after signoff' maintenanceperiods.

During inspection, note theVSWR reading. If the readingshows zero VSWR, congratulateyourself on a perfect line only afterthe unit has been checked out.More than likely, it isn't telling thetruth. But don't resort to tappingor wiggling wires. You may trip the

transmitter off the air. Temporarily,borrow the diode from the forwardposition and substitute it for thereflected diode. If the meter nowreads, the diode is defective. Don'tswitch the cable positions, interchange the diodes only! You stillwant to read reflected power! If thediode is OK, you can't go anyfurther without taking the transmitter off the air.After sign-off, you can check out




the cable with an ohmmeter. Workfrom the diode end, then at theinput to the unit, and at the meter.At the meter itself you will be pastthe calibrating resistor, so use aresistor in series with the ohmmeterlead, otherwise you can damage themeter (if it was OK in the firstplace). Should the meter relay bedefective, it is less expensive to replace it than to repair it.

If normal readings are obtainedon a daily basis, during sign offmaintenance, occasionally, checkout the trip of the circuit. Followthe regular setup, although it isn'tnecessary to do the whole procedure. Just reduce transmitter powerto about I. I and then change theleads to the diodes. Increase poweruntil the unit trips. Doing thisoccasionally will assure you that theunit is working properly.

Other areas to check during thismaintenance are the external relaycontacts and connections. Cleanany burnt contacts or replace them.If the relay is the type with nonreplaceable contacts and they arebadly burnt, replace the entire relay. Erratic contacts on the relayare the same as loose contacts onthe interlocks in the transmitter,and intermittent transmitter outages are a possibility.

Lightning can cause high line

surges, and these surges can causethe relay contacts to burn off orburn together. Such surges can alsodamage the internal relay in themeter. If such failures do occur,you may not be able to get thetransmitter on the air at all. Disconnecting the unit entirely fromthe transmitter is the best procedure in this case. This will alsoallow removing the unit to thebench for repairs.

To remove the unit, make surepower to the transmitter is turnedoff, because the interlock voltagewill be in the unit. Then disconnectits local AC power. Next, disconnect the leads that connect to thetransmitter interlocks. Ordinarily,these are connected to a terminalstrip on the sentry unit, so they areeasy to disconnect. These two wiresare a series connection of the interlocks normally through the sentryrelay, so you now must connectthem together. But rather thantwist or solder them together, use abolt and nut. This will preserve thewire lugs when you will reinstall therepaired sentry. Make sure all thebare surfaces of the connection aretaped to prevent shorting out theinterlock voltage.

If the meter relay itself is defective, try to get an exact replacementfrom the manufacturer. Before you

DISCONNECT CABLE"FROM DIODE

METER

INPUT TERMINALS• CAL. POT.

II

IIII

\ !"I I\ II I

\__-- ---- - --- - - - -- --- -- - _,!

~ 11\~)- )____ ,,,----------------'IIIIIIIIIII\\I\ I.--'

OHMMETER

' 2~,' "-:E~~S1~RI

Fig. 3 You can check the meter circuit with an ohmmeter. Disconnect fromdiode, and make sure transmitter is off. Add a series resistor to the lead whenchecking the movement itself.

1 August, 1973

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TRANSMITTER INTERLOCK CIRCUITS

120VAC

Fig. 4 (A) At right-relay contacts are series connected withinterlocks. (B) Below, disconnectfrom defective sentry. Bolt leadstogether and tape for protection.

r--------------,I I.....---<>--. : CONTACTS

1 NORMA LLY CLOSED: DUR I NG OPERATION: UNLESS TR I PPED

III

t=IIIIIIIIIIII IL---------------

RELAY IN PROTECTION UNIT

INTERLOCK CIRCUITS

120V AC

strip off all the leads to the oldmeter, you should make a roughsketch of the wiring, terminals, wirecolor coding, and compare this withthe schematic for its operation.

The meter you get for a replacement may not be an exact replacement either electrically or physically. Sometimes the manufacturer willchange the type of meter they aresupplying. This is OK so long asyou don't have too many physicalmodifications to make. If it is adifferent model of meter, make surethere is a schematic sent along withit. The meter may have a schematicimprinted on its case which will tellyou what you need to know. Unlessthe meter is exactly the same as theone you took out, don't wire it upwithout a circuit diagram. Youcan't assume that the terminals arewired internally the same as the oldone. If you wire it up incorrectly,you can burn it out as soon as youplug it into the AC power.

During normal operation, theunit simply monitors the line. Butyou may have to operate in abnormal periods, such as sleet or icingat the antenna. The VSWR will rise

"BOLT TOGETHERAND TAPE

r--------------,: =::,i. :I II I II 1 II I I

: ~I :I II II II II II II II I

~--------------~PROTECTION UNIT DEFECTIVE

because of the antenna detuningand will trip the sentry. Eventhough the VSWR is higher, youcan still operate If you reduce thetransmitter power. How much youreduce the power will depend uponhow close to maximum ratings youare operating the line. As far as thesentry is concerned, it is calibratedat 100 percent power and is readingthe reflected power. Reducing thetransmitter power will not changethe ratio, but it will reduce theactual amount of reflected power.The unit won't trip so long as theamount of reflected power does notcause the meter to rise above thetrip point. The meter is not indicating true VSWR under these conditions, because it is now essentiallyuncalibrated.

The cost of the sentry unit issmall in comparison to the irivestment in the antenna and line, tosay nothing of the days the stationcould be off the air to replace aburned up line or antenna. Somestations have operated for yearswithout such a protection circuitand have never had problems, butthen, everyone can't be that lucky.




The ImpatientListener-Alarm

By Fred MooreStation WDZDecatur, Ill.

Build up this circuit on a 3 x 3"piece of pertboard, mount it on a3" rack panel with a miniaturespeaker and a switch or two andyou will never have to ask thequestion, "Are we on the air?"

Lose either modulation or carrierand this little wailer screams bloodymurder until both return or untilsomebody kills its power. It doesn'tholler on short lapses of audio,either. I built mine for 30 secondsof "patience". You may choose to"empirically determine" (cut-andtry) the value of Cl for a differentinterval.

Circuit DescriptionTransistors Q2 and Q3 form a

"siren" generator, giving the alarmits voice. This part of the circuit isstraight out of the RCA HobbyCircuits Manual. Adding Ql givesus a delayable switch on theoscillator operating at very low basecurrent. This way we can use plentyof R and C to get all the time delaywe want.

Rectified audio from the 8-0hmspeaker output of the modulationmonitor drives Ql, holding itsaturated. The siren generator can'toperate this way because Q2's baseis too negative. But when the audiodisappears (for any reason - carrieroff, program line failure, etc.) Clbleeds into Ql's base circuitthrough the lOOK resistor. When

August, 1973

The arrow points to the WDZ impatient listener alarm.Such alarms are vital to automated stations.

the charge is about gone, Ql 'scollector resistance Jets Q2's basego positive enough to start theawful racket, which promptly getsworse as C2 charges. The frequencystabilizes long before your nervesdo, and the urge to do something tocause quiet soon gets irresistable.

The only connections to the littlemonster are about .8 Volt of inputaudio from the modulation monitorand 9 Volts of DC power. Ipowered mine from one of thosesmall black boxes built on the backof an AC plug. They're normallyused to run a transistor radiowithout batteries. Don't forget thepower switch or you'll have aninstant insanity machine.

In OperationThis alarm is in use at WDZ, a

daytimer, so each signoff checks thecircuit daily. At a 24-hour station, anormally closed push-button inseries with the input might prove asafer test than taking the transmitter or program off, a practicethat is still generally frowned on bymanagement.

If you want to use some otheraudio source, play with transformerimpedances and the 18K resistor sothat your circuit doesn't load itssource. Normal levels should produce about 10 Volts of DC acrossCl, measured with a VTVM orequivalent.

Happiness is knowing for sureyou're on the air. D

PLUG-MOUN TEODC SUPPlY

29



Fig. 1 Here you seetwo cameras beingtested and compared.Note that first set upagainst a test pattern.Then they will bepointed at a test scene.

Part 2

Color camera basicsBy Joe Roizen

Telegen, Mountain View, Calif.

A three-tube color camera isessentially three monochromecameras in which the images fromthe individual pick up tubes havebeen super imposed on each other.The process of setting up a colorcamera is a fairly complex sequenceof amplitude and positional adjustments that establish the correctcolorimetery and the propergeometry of the image.

The best evaluation of performance and stability of a colorcamera can be made with a precision RGB monitor connecteddirectly to the camera outputsahead of the encoder. After a sufficient warm up period (30 minutes)the camera should exhibit essentially the same colorimetery andacceptable registration for at leastfour hours and should require littlereadjustment when turned on againthe next day.

Colorimetery drift is especiallynoticeable if two or three cameras

30

are color balanced and matched toeach other at the start of a production and then progressively exhibitrelative color shift while beingswitched on the same scenes. Whileless subjectively annoying, registration drift will slowly decrease imageresolution in an RGB camera to thepoint where the set up proceduremust be repeated.

Cameras with YRB matrixing arealmost immune to normal smallregistration drifts which occur inmost cameras over an eight-hour'Period. Very expensive studiocameras have automatic correctivecircuits for white balance and registration as optional features onthem. These extras are not available on the lower cost cameras andthey must depend solely on thebasic stability of the circuitry toprovide adequate performance.

Special test charts are availablefor testing resolution, registrationand color balance. When usingthese charts it is important toassess performance over the entireimage area and not just in themiddle of the image. Cameras withpoor scan linearities, mismatchedyokes, poor internal optics, etc., will

usually show significant fall offtoward the corners.

Some cameras use full size optical images on all three pick-uptubes, others minify the red andblue image since theoretically theseare limited acuity color channels.While both approaches are valid,the scans of the minified imagesmay require dynamic correction tomaintain good registration betweenthe narrower scan angles of thered/blue tubes and the normal scanof the green tube.

Self ContainedVersus CCU

Yet another variability in colorcamera configuration is the "SelfContained" versus "CCU" (cameracontrol unit) type. Self-containedcameras are usually cheaper, lighterand simpler than the separate control unit type. They are preferablewhere equipment and personnelbudgets are at a minimum andwhere the camera operator candouble as a technical type and dohis own setup, ride gain, adjustfocus, vary iris and still frame in apleasing picture.

Self-contained cameras have




built-in encoders and sync generators making them independantdevices that can be easily moved toremote locations for out of studiocoverage. However, they do havesome disadvantages. Maintenance,measurement and manipulation arenot as easy or as flexible as on aCCU type camera.

The CCU type camera is themost appropriate for studio orsophisticated remote application.The camera operator is concernedonly with the mechanics andesthetics of image composition,framing, focus, pan, tilt, zoom etc.,while the video controller handlesthe electronics involved with waveform monitoring, signal balance,iris adjustments etc.

The camera should have delegation controls allowing the transferof various functions from thecamera head to the CCU and viceversa. The CCU unit should permitfinal trim adjustments on registration and color balance, control ofthe iris, video gain and pedestaland an optional choice of degree ofenhancement.

The associated waveform andpicture monitor in the CCU shouldbe switchable to a variety of testsignals including individual RGBoutputs, subtractive and additivernatrixing for registration adjustment, field and line waveform ratesand RGB sequenced displays(parade). The camera head shouldallow easy access to the main controls for initial setups and to thepick-up tubes for simple replacement and positive positional index-

Management HighlightsThe author explains that cameracomparison tests can tell youquite a lot about what you'll getafter a purchase. He also explains how to make the testsand how to compare camerafeat u res from a cost/ performance standpoint.

August, 1973

ing. Provision for indexed gammasettings are also useful in setting upthe camera. Some cameras can beused in either self-contained orCCU configurations, the conversionbeing accomplished easily.

ViewfindersThe viewfinder serves as the

major device by which the cameraoperator can frame and focus theimage. It is important therefore tohave a finder that has the followingcharacteristics.1. Maximum practical size for

operational ease.2. Good contrast and brightness

range to combat high ambientlighting.

3. Video peaking to enhanceedges and aid determination ofcritical focus.

4. Tiltable shading to accommodate unusual shooting anglesor lighting conditions.

S. Easily removable in case offailure or for interchange.

6. External video-feed input toallow the camera operator tosee special effect inserts, etc.

7. External output to feed outsidemonitor in case of emergency.

8. A high degree of reliabilitysince the loss of the viewfinderfunction can severely handicapa production in progress.

Cable CompensationThe trend toward smaller cables

Fig. 2 Camera features and optionscan be almost bewildering. Your production needs are thefirst criteria. But ifyou ask why certaincameras are bought,the answer often isthat engineers recommend cameras(and other equipment) to other engineers.

between the carnera and the CCUincreases the need for compensatingcircuits to accommodate line lossesin the cables. The camera shouldhave adjustable cable compensationthat can handle the longest cablethat is expected to be used.

Peripheral FeetutesThere are a wide variety of acces

sory or built-in features that may ormay not be worth the added costand complexity they engender. Hereis a partial list of such devices.1. Internal Sync Generator2. Internal Gen Lock3. Remote Iris and Gain

control panel4. Internal color bar patternS. Integral encoder6. Built-in system test signal7. G.G.B. Enhancer8. Composite Enhancer9. Switchable "paint pots"

1O. Split audio systems11. Internal filter wheel.12. Elapsed time indicator13. Attachable diascope14. Talley light defeat1S. Modification kits to upgrade

performance.

Camera ComparisonThe best way to compare color

camera performance is by lookingat the competing cameras at thesame time and with the same subject material. Camera manufacturers are often reluctant to do

31



1'\UA'l'I T~ M'f ~lRr OfF ANO(:,eí A TAN "?11

this because of the highly subjectivenature of such evaluations and thedirect exposure of each of theiradvantages and deficiencies to thecompetitors's staff.

Ideally, after a short set of instructions on how to operate eachcamera has been absorbed, thecameras should be left to the customers studio personnel to operateand evaluate against a check list ofdesired performance parameters. Ifa good VTR is available, then theresults of each test can be recordedand kept for subsequent criticalreview. The suggested test procedure is as follows:

1. The cameras are optimized bythe manufacturer's representatives to make sure they areoperating properly and have nosignificant deficiencies.

2. A series of tests are conductedunder the scrutiny of thecamera company representatives and recorded with appro-priate audio commentary. t?

3. The cameras are turned offand left overnight in the studioor allowed to cool to ambientroom temperature.

4. The manufacturers representatives are asked to leavecameras for further testingwithout their presence.

S. The cameras are turned on andallowed to warm up for fiveminutes at which time a shortrecording is made of a registration and chip chart image oneach camera. No controls are

32

adjusted at this time!6. A further warm up period of at

least 25 minutes is allowed andwith no control adjustmentsthe cameras are evaluated withregistration and chip chartsagain. Short recordings ofthese tests· are made.

7. Operational camera controlsare now optimized and notesshould be made of the degreeof manipulation and the timeconsumed in doing this. Newrecordings at the optimum settings are made.

8. The cameras are now ready fora series of critical tests with thefollowing conditions:

a) Registration chart. Notegeometery of the threesuperimposed images especially out to the edges andcorners of the chart. Be surethe cameras scan equi sizedimages.

b] Resolution chart. Checkhorizontal and verticalresolution both at the centerand in the corners of theimage.

e) Grey scale/chip chart.Check for color balance especially in the low luminance chips where colorshading is most noticeable.For best evaluation, use thesame monitor for allcameras so as to avoidmonitor phospor chromaticity differences or set upvariations.

d) Point cameras at a widevariety of colored objects(the easiest to obtain and setup are grocery and foodproducts) of various degreesof saturation and notecolorimetric response ofeach camera.

e) Incrementally reduce lightlevels and recheck eachcamera for adaptability tothe new level and for colortracking. Pan from side toside to check for image lag.

f) Use one or more humansubjects with head andshoulder shots against avariety of solid and variedcolored backdrops. Noteoverall colorimetery andcolor shading in dark areas.

g) After a few hours of operation and without readjustingany of the registration andcolor balance controls,recheck the cameras on thetest charts and record theresults.

h] Check all lens controls forsmooth operation and properfocal tracking of the zoommechanism.

i) Check the viewfinder forframing accuracy, range ofbrightness, contrast, imagecrispening, etc.

j) Roll the camera around, tapit lightly on the sides, manipulate cable plugs, etc., tocheck for microphonics,intermittents, poor connections, etc. Open and closecamera housing, wherepractical, and note effect onthe picture.

Assuming the cameras havepassed all of these tests, you cannow invite the camera purveyorsback in to 'recheck your results andto explain the unique features thatmake each camera the best buy forthe money.The author wishes to thank Fred

Haines for his meticulous reviewand useful suggestions for thisarticle. His fund of knowledgeabout color cameras seems inexhaustable. In addition, valuableinformation came from Dr. Skipwith Athey, William Higgins, andMark Broemmelsek. Ed Flowersand Donna Roizen helped with thephotographs and the manuscript. D




ExperimentalPub Iic Access

William Johnson of the FederalCommunication Commission'sCable Television Bureau describedthe Commission's rules on publicaccess cable TV programming as"still in the experimental stage" atan Eyeopener panel on "PublicAccess to CATV" held at theNational Cable Television Association's annual convention.Johnson said the Commission was

"listening" to some of the problemsthat have already arisen in currentpublic access programming. Hecalled the present rules which barcable operators from exercisingcontrol of programming but alsorequire that no obscene material bepresented "unfortunate for thecable operator but an inevitablesi tu ati on." Proposals to institutionalize funding for public accessby assessing cable operators anadditional fee would be examinedby the Commission, he said, askingthe practical question "Would thecable operator be able to bear theadditional financial burden of suchan assessment?"Johnson said that the Com

mission's thinking, as reflected inthe rules, on technical standards forpublic access channels is thatstringent technical standards inhibitlocal programming efforts andtherefore must not be applied topublic access channels. He expressed concern that strict technicalstandards imposed at the state orlocal level would have the sameeffect of impeding local programming efforts before they couldreally get going.

Richard Galkin of SterlingCommunications Corp., New YorkCity, concurred that the mainproblem of public access programming at this point is raising publicawareness of it. Panelists Galkin,Cohen and Shamberg discussedpractical problems they encountered in running public accessoperations. Johnson explained theFCC's current rules on publicaccess programming which CharlesTate challenged as recognizingindividual rights but ignoring groupand community rights.

August, 1973

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Listen tothe Soundof Dependability

STL test tapes maintain a reputation as the most dependableand accurate tapes you can buy because of the consistentlyhigh standards produced on the finest precision equipment.In addition, they are available in more sizes than thatoffered by any other manufacturer in the world.Listen to the sound of dependability ... and accuracy. OrderSTL test tapes and find out where your system really is.All audio widths from 150 mil. to 2-inch. Prompt deliveryinsures freshness.

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Part 2 of a series

Basic Digital Logic ReviewBy John LeeHewlett Packard

The previous article discussed thetype of logic known as combinatoria I logic. These were functionswhich have no memory or storagecapability. They form the decisionmaking elements of any logic system. As equally important as thedecision making elements to anylogic circuit are the memory andstorage devices. These devices belong to a class of logic functionscalled sequential logic. They will bethe topic of Part Two of this series.

Sequential LogicThe basic building block of se

quential devices and circuits is theflip-flop. The flip-flop is a bi-stable(2 state) device which can be

*I j 1

switched easily from one state tothe other. The time at which theoutput switches is controlled by asignal called the clock. As we'll seelater, there are several clockingmodes. The state to which the output goes upon the appearance ofthe clock signal is controlled by theflip-flop data input.

As with combinatorial devices,the flip-flop's operation can best bedescribed by the use of a logic truthtable. Due to the clocked nature ofthese devices, the truth table forflip-flops and other sequential elements are time dependent. Thismeans we need to express not onlythe input state required to cause agiven output state to occur, but wemust also indicate at what time thisinput state occurs.

Figure 1 shows a truth table for

o.

the simplest flip-flop, the D typeflip-flop. The timing information isindicated by the subscript t andt + 1. D¡ represents the state of theD input just prior to the occurrenceof a clock pulse and Qt+ 1 represents the resulting output just afterthe clock pulse. Between clockpulses the Q output will remainconstant regardless of the signalactivity on the D input. Thus, theD flip-flop remembers the state ofthe input at the occurrence of aclock pulse.

Basic Clocking ModesBefore discussing the various

types of flip-flops it is important tounderstand the three basic clockingmodes (Figure 2). These are edgetriggered, level triggered and master slave. In the edge triggered

EDGETRIGGEREDMODE

CLOCK

POSITIVE EDGETRIGGERED

NEGATIVE EDGETRIGGERED

LEVELTRIGGEREDMODE

Fig. 1 D type flip-flop. Timing information for sequentialdevices is usually indicated in subscripts on the parametersof the truth table. The D type flip-flop stored the state of theD input that existed just prior to the clock pulse. The outputswitches on the occurrence of the clock pulse.

~OUTPUTFOLLO~S

INPUT

MASTER SLAVE MODE

Fig. 2 Edge triggered: The output state changes on theoccurrence of a specific voltage on the edge of the clock. Leveltriggered: The output follows the input while the clock is abovethe threshold voltage. Master slave: Input information isallowed to enter the flip-flop between (2) and (3) and istransferred to the output at (4).

34

(I) OUTPUTSARE ISOLATED(2) INPUT INFORMATION ENTERED13l INPUTS DISABLED(41 INFORMATION TRANSFERRED




Why we've startedwearing the star.

You may have noticed a new symbol on ourcover or index page: the star of the American Business Press.

This star means we've been elected to join aselect group of business and professional journals in a specialassociation. And it means something special to you.

How we earned our star.As a memher of the American Business Press, we

have pledged to uphold the highest ethical standards ofjournalism. Which means we are dedicated first and foremostto your interests as a professional reader by (1)strivingconstantly for honest and effective presentation of all newsand articles, (2)maintaining absolute editorial independenceand (3) refusing to accept any advertising we know to befalse, misleading or unfair.

Let our symbol be your guide.Of the 2,335business magazines published today,

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We're proud to have earned MAber.our star and proud to recommend any Bu~~~anpublication that wears it. Press

August, 1973 35



Rt I St I Ot IOt+l ¡ so o o o L-...l__..I I p 'o o o

Q I I r-L___./ I ~Q

o 1 oo I I I <, / I I CLOCK

o o oo 1 o

o UNDETERMINATED ~QI I ~ "* I P4---o

UNDETERMINATED ~

R

Fig. 3 R-S (Reset-Set) flip-flop. This NANO gate implementation is unclocked.The subscripts t and t + 1 now refer to the amount of time required for achange on the input to cause a change on the output. Qt+ 1 represents theoutput state this time interval after applying the inputs Rt and St.

Fig. 5 An R-S flip-flop with presetand clear inputs. Regardless of clock,R, and S states, the preset or clearinput will directly affect the output.

mode, the flip-flop changes state onthe occurrence of a specific voltagelevel on either the rising or fallingclock edge. If the flip-flop switch ison the rising edge, it is called apositive edge triggered device. If theswitch is on the falling edge, it iscalled a negative edge triggereddevice.

In the level triggered mode, theflip-flop output is allowed to followthe input as long as the clock signalis above a specific threshold voltagelevel. When the clock goes belowthis level, the output captures thestate of the input and remainsconstant until the clock again risesabove the threshold level. This isoften referred to as a latch mode ofoperation.The most sophisticated mode is

36

Jt Kt Ot Ot+lI

0I

0I

0I 0 I

o o I I-J o-

o I o oo I 1 o1 o o 1

K CLOCK Q- ~1 o 1 11 1 o 1 I1 1 1 o

Fig. 6 A J-K flip-flop. It's similar toan R-S flip-flop. The J=K=1 state isdefined as a toggle mode. In thisstate, each clock pulse causes theoutput to change states.

the master slave mode. As the clocksignal reaches the low threshold atPoint 1, the outputs are isolatedfrom the input. At Point 2 theinformation at the input is enabledto enter the flip-flop but not transmitted to the outputs. During theinterval from Point 2 to Point 3 theinformation is continuously enteredinto the flip-flop. At Point 3 theinputs are disabled and the currentinformation stored. At Point 4 thisinformation is transmitted and heldon the output pins.

In addition to the D type flipflop (D stands for data since theoutput goes to the data input stateon the occurrence of a clock pulse),there are four other basic flip-flops.These are the R-S, J-K, T, andLATCH.

Fig. 4 A NANO gate implementation of aclocked R-S flip-flop. Only when clock ishigh can R and S affect the output.

+5

K CLOCK Q

QQ

T

T

Fig. 7 The T (Toggle} flip-flop. Theoutput of the toggle flip-flop changesstate on the occurrence of a pulse atthe T input. This device can easily beimplemented from a J-K flip-flop asshown.

R-S Flip-FlopThe R-S (reset, set) flip-flop is a

very basic and often used circuit. Itmay or may not have a clock input,since the occurrence of the inputsignal can determine the time atwhich the output changes state.

Figure 3 shows the truth tableand implementation using NANOgates for this device. Unlike theother flip-flops which can be purchased in an integrated circuitpackage, the R-S flip-flop is mostoften built from NANO or NORgates.

As you can see from the R-Struth table, when R and S are bothO, the output Q does not changestates. When S is 1 and Q is O, theQ output will change to 1, it is thusset. When S is 1 and Q is 1, Q re-




Fig. 8 7490 Decade7490 DECADECOUNTER

INPUTcounter. Flip-flops 8, C, A NC A D GND B eand O form a divide by 5 D D D D Dcircuit. Flip-flop A isused as a divide by 2(toggle) flip-flop. Whenthe A output is con-nected to the clock ofthe B (BO input), then a

I FFA FFB FFC Lrdecade (divide by 10)counter results. J Q J Q J Q Q

CL CL CL I I YnJ:LK K K Q

mains unchanged, since it was already in the set condition. When Ris 1 and Q is 1, Q will change to O.It thus becomes reset. If Q isalready O then it will remain unchanged. The state in whichR=S=l is undefined. It can not bedetermined whether the device willset or reset. In most designs thisstate is unallowed.

R-S flip-flops can also beclocked. Figure 4 shows a NANOgate implementation of a clockedR-S flip-flop. Only when the clockis 1 are the intermediate signals R*and S* allowed to follow the inputsR and S. So while the clock is O,the outputs are isolated from theinputs and remain in a constantstate.Common to many flip-flops are

preset and clear inputs. Some haveonly one or the other, and somehave both. These inputs allow thestate of a flip-flop to be set to 1 orO regardless of the clock or inputsignals.

As an example, Figure 5 showsan R-S flip-flop implemented withNANO gates with both preset andclear inputs. It is obvious that re-

D C Bo o oo o Io I OO I II O Oo o o

gardless of the input and clockstates, a 1 on the preset line willcause the Q output to be a 1 and ifheld longer than the propagationdelay time of 1 gate, the output willremain in the set condition afterthe preset signal is removed. Similarily, the clear input will cause theoutput Q to become O.

J-K Flip-FlopThe J-K flip-flop (Figure 6) is

very similar to the R-S device, withthe 1 input corresponding to the Sinput and K input corresponding tothe R input. The distinction is thatthe J=K=l, (R=S=l), state whichwas previously undefined is now defined to be a toggle mode. That is,if J=K=l when a clock pulse occurs, then the output will changestates. If it was a I it will become aO. If it was a O it will become a I,hence, it toggles. J-K flip-flops canbe either edge triggered or masterslave devices.

Toggle Flip-FlopAs a special case of the J-K

flip-flop, the toggle flip-flop is adevice with only a clock input and

whose output changes state (or toggles) on the occurrence of eachclock pulse. A toggle flip-flop canbe easily implemented from a J-Kflip-flop (Figure 7) by tying boththe J and K inputs high through aresistor to SY.

Latch Flip-FlopThe latch flip-flop is really a

form of a O type device. In general,O type flip-flops are edge triggereddevices. When a O flip-flop is leveltriggered it is called a latch. Alatch's output follows the input aslong as the clock signal is high.When the clock goes low it latchesthe output to the input state at thatmoment. That's how we get theterm "latch".

CountersUsing flip-flops as a basic storage

unit and building block. more sophisticated sequential devices canbe implemented. Counters representa large class of sequential devices.

Using feedback of the flip-flopoutputs, many types of countersare built. Decade, divide by 12,binary, and variable module are

BD INPUT

August, 1973

D D DNCRESET TOO

D D DVee RESET TO9

37



*Ji1&41'AZY,wt~t/Pi7/:1¥tf R7,<All ~Mr,£ W/lflDPt~ 1<0:Mtl/!'1ft!Nrw11Y11ff P/Jd'T l'f:KX.."

just a few of the varieties availabletoday. Because of the vast numberof devices it is impossible to discusseach counter individually. Therefore, let's analyze a decade counterin detail to see how counters can bedesigned from flip-flops.

Decade CountersThe counter we will study is a

7490 Decade Counter. As you cansee in the logic diagram of the 7490Decade Counter (Figure 8), the decade counter is composed of J-Kand R-S flip-flops. Without makingany external connections, this decade counter acts as a divide by 2(see FFA) and a divide by 5 (seeFFB, C, D) counter.To understand the divide by 5

operation, consider the desired sequence of outputs shown in Figure8. The B flip-flop acts like a divideby 2, except immediately followingthe reset to O condition. This resetoccurs on the first clock after the Doutput goes high. Using the Doutput as a reset to the D flip-flopand using the D output as an input

SERIALINPUT

Q

QK K

to the J of the B flip-flop will causethe outputs of both these devices togo to O on the next clock pulse.

Since the output of B prior tothis clock pulse is O, this will havethe affect of causing the B and Cflip-flops to skip a count. Lookingat the B and C states in the truthtable, you see that this is what theydo. The only remaining problem ishow to get the D output to go highat the proper time.The D will go high following the

condition that B and C are bothhigh. Thus using the AND functionof the B and C flip-flop output todrive the S input of the D flip-flopswill cause the D output to go highat the proper time. This then explains the feedback paths used togenerate the divide by 5 signal.

It should be noted that the unused inputs are assumed to be inthe high state. In order to get adivide by IO (a decade counter), itis only necessary to divide the clockinput of the B flip-flop by 2. Thuswhen the output of the A flip-flopis used to drive the clock of the Bflip-flop (note that A is used as atoggle or divide by 2 circuit) andthe clock input of A is used as thecount input, then a decade counteris achieved.

Shift RegistersShift registers are another impor

tant group of sequential devicesbased upon flip-flops as a basicbuilding unit. They are characterized by their length and type ofdata they accept. There are fourtypes of data. They are parallel

Q

in/parallel out, serial in/serial out,serial in/parallel out, and parallelin/serial out. To understand theoperation of shift registers considerthe serial in/serial out 8 bit shiftregister shown in Figure 9.As implied in the name of this

device, the maximum number ofbits that can be stored is 8. lnforma tion is entered into the shiftregister serially and recovered serially. As clock pulses occur, the dataat the left most flip-flop is inputand the stored data is shifted rightl flip-flop.The 8 bit shift register is built

from 8 R-S flip-flops. While thisparticular shift register is able toshift data in only the right direction, devices are built which allowinformation to be transferred eitherleft or right. For example, theparallel in/parallel out 4 bit shiftright/shift left shift register shownin Figure 10. Controlled by themode input, this device can load all4 flip-flops at one time (in parallel)and shift that data right or left witheach clock pulse it receives. Whenrequired, the data can be recoveredfrom the shift register as 4 bits inparallel.

While many more sequential devices exist, the flip-flops, counters,and shift registers are the basicbuilding blocks. As mentioned inthe Part One, manufacturer's datasheets and the text of John D.Lenk, Handbook Of Logic Circuitsand of H. V. Malmstadt and C. G.Enke, Digital Electronics For Scientists provide a deeper presentationof sequential logic. O

SERIALOUTPUT

QQ Q QQ Q

Q Q K KQ K Q QQ KK Q K

Fig. 9 An 8 Bit serial in I serial out shift register. As clock pulses occur, data isentered from the left and all stored data is shifted right 1 bit.

38 BROADCAST ENGINEERING



CCTV Production TechniquesUntil the last decade, the high price of equipment

necessitated that television be used primarily as anentertainment medium. Recently, because of the introduction of television equipment that is priced far belowthat used in the commercial broadcast industry, closedcircuit television has found numerous applications inCable TV, education, medicine, sports, business, andindustry.Closed-Circuit Television Production Techniques,

written by Larry G. Goodwin and Thomas Koehring, isconcerned with the production principles that areinvolved in closed-circuit television presentations. Itcovers the technical aspects, studio layout, cameraoperations, audio, lighting, graphics and sets, scripts,and presentation techniques of the field.

This book offers closed-circuit television users simple, but thorough, production principles that can beused in day-to-day operations. It is available throughthe Howard W. Sams & Co., Inc., Indianapolis, Ind.


Solid State GuideToday, the technician is expected to assume techni

cal responsibilities that formerly were controlled byengineers. As a consequence, the valuable electronicstechnician must have more than a superficial knowledge of the popular solid-state components now in use.The main objective of the Comprehensive Guide ToSolid-State Electronics, written by George B. Ruthkowski, is to help technicians meet this challenge. Theauthor not only discusses the fundamentals, but alsodevelops the student's ability to select proper designcomponents for solid-state electronic circuits.

The book begins by explaining common semiconductor materials. Other chapters discuss the ZenerDiode, the junction transistor, the silicon-controlledrectifier, the field effect-transistor and integrated circuits.

A modified programmed style is used throughout thebook.Each point discussed is followed by at least oneexample. The student is encouraged to work eachsample problem before referring to its solution. Theanswers to the odd-numbered end-of-chapter problemsare provided at the end of the book. These problems,with the examples, make this book a highly-recommended source for either self-study or classroom use.

This book is available through Howard W. Sams &Co., Inc., Indianapolis, Ind.

For More Details Circle (91) on Reply Card(Continued on page 44)

August, 1973

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More onIM testingBy Dennis CiapuraWLIF, Baltimore, Md.

Since almost all broadcast systems are limited bandwidth animals, IM distortion testing procedures yield many advantages overthe more usual harmonic distortionmeasurements. The futility of harmonic analysis of high frequencydistortion in FM broadcast systemswhere the harmonics never reachthe modulator is a phenomena wellknown to many engineers. In AMmodulators it is sometimes as difficult to avoid audio intermod as it isto avoid traffic on the freeway.

There are, however, some lessobvious uses for IM test gear, primarily in testing program sourceequipment, i.e., tape and disc gear.As is often the case, the best way toobtain the fullest service from a testtechnique or procedure is to fully

NON-LINEARTRANSFER

DUAL TONEINPUTS IGNAL

40

The author (r) discusses transmitter distortion measurements with Jim Sharon, WLIF FMOperations Director.

understand the theory of operationof the test equipment and the testprocess.

How IM Distortion OccursIM distortion can be generated in

many ways, but the most commoncause is non-linearity of powertransfer. Figure 1 shows how twotones are affected by a non-lineartransfer curve. As you can see fromthe diagram, the higher amplitudelower tone has modulated thehigher tone; a contest often lost byviolins to bass. If the high tone isnow looked upon as an AM RFcarrier and detected, the amplitudemodulation components are the actual distortion. These consist primarily of F, + F2 and F1 - F2, butnot entirely. We must remember

MODULATION OFHIGH TONE

DISTORTED OUTPUT

1.M. COMPONENTS!DETECTED AND FILTERED!

Fig. 1 Scope drawingsshow how a non-lineartransfer causes IM.

that the same non-linearity thatcaused the intermodulation alsocaused harmonics to be generated.These harmonics also intermodulateand as you can see in the table ofoutput components in Figure 2,things are not as simple as theyseemed at first.

From a practical standpointthough, the rest of the IM productsare usually of negligible level because of the relatively low level ofthe harmonics (unless we are talking about a really gross non-linearity), cancellation of some of thecomponents and the rather narrowbandpass of the measuring equipment. Speaking of measuringequipment, this would be an idealplace to stop and examine the testcircuitry and see how these instru-

Management HighlightsIf your stations' decision making teamis like most others, it sells against itssound and service. Here are expandedIM tests that can help interrogate yoursound so that service is easier toguarantee.

Figure 2Table of intermod components

for distorted transferof 60 & 5000 hz.

5k 605k 1205k 1805k 240

Etc.

10k 6010k 12010k 1801Ok 240

Etc.

15k 6015k 12015k 18015k 240

Etc.

BROADCAST ENGINEERINGwww.americanradiohistory.com


r--------- ------------ ---- -------------------------------- -------¡-_' '' '

I::i:I:'lt

''

HIGHFREQUENCY

ose.LOW

FREQUENCYose.

MIXER DETECTOR

EQUIPMENTUNDER TEST

HIGH PASSFILTERI

IIL _

I -.., r

I \I- II-·

II~-

III

I4100 100

10

,--- - - - -- -- - - - - - - - -·-- - - - - - - - - - - - - - - - -- - - -----L-- -- - - - .J

Fig. 3 Simplified block diagram of IM distortion meter.

ments operate.

How The Test Gear WorksFigure 3 is a block diagram

which describes in general termshow these units operate. Most IMdistortion test equipment containsbuilt-in low and high frequencytone sources. In the less expensiveunits, the 60 Hz low tone is tappedoff of the power line for simplicity.In the more sophisticated units,internal tone generators are provided. The high frequency tonegenerator should, of course, be veryamplitude stable to prevent anymodulation of the test signal beforeit leaves the test equipment. TheCrown I.M.A. analyzer actually employs two FET controlled oscillatorsfor unusual stability.The test tones are mixed linearly

and with extreme isolation betweengenerators to prevent any intermodulation of the test signals. Theratio of low to high tone levels isusually the SMPTE standard of 4: 1which is usually satisfactory. Theselevels usually can be easily varied,and it is sometimes desirable to usea higher ratio for increased sensitivity, particularly if you are tracingdown a specific problem.

The test signal is fed into theequipment under test at the desiredratio and level, and the output fedback into the IM distortion analyzer for the distortion readout. Theoutput of the device being testedfirst passes through an attenuatorand input amplifier circuit. Nextthe signal goes to a high pass filterwhich removes the low frequencycomponents and then on to an AM

August, 1973

500 lK 2K 5K !OK 10K 50K

Fig. 4 Filter response curve of a high quality IM meter.

detector circuit to retrieve anymodulation of the high tone. Theoutput of this detector is thenpassed through a low pass filter toremove the high frequency carrier.This filter usually has a 500 - 1000Hz cut-off frequency.

Figure 4 shows typical filter response curves for the Crown l.M.A.While these curves are extremelysharp (7 pole butterworth filters areemployed in this unit), the cornerfrequencies are representative ofthose found in most IM distortiontesting equipment. The distortioncomponents that remain are thenpassed on to the metering circuitry.These same or additional meteringcircuits are employed for input andoutput level and calibration levelmeasurements.

Probably the best way to understand how the JM meters work is tothink of them as a fixed tuned AMradio receiver which demodulatesthe 4000 to 8000 Hz band. The

/,)

~tí'~~--~

RMS RESPONDING---.._/rMETER

/vv

/ VAVERAGE RESPONDING/ I '.'./

/ /

/ V--v VI

V_¡....-v

90

80

75

70

65

60LI 2:1 4:1 7:1 10:1

TONERATl OFig. 5 Chart showing percent of normal meter indication required toachieve voltage level equivalent tosingle tone.

The author isshown here explaining IM tests methods for Station Manager Frank DeRose.This is the kind ofcommunication thatmust exist withinthe station. Anyway,from the smiles, theresults at WLIFmust have beengood.

41



,.

l

\\

""-.,.._ <, -----r--t---

,, OROP-ÓUTBELOWrus LEVEL

overall bandpass is usually about 1kHz and the carrier is removed asin an AM radio.

Practical Applicationsand Methods

While a low tone of 60 Hz isusually employed for standard IMtests, other tones may be used if ahigher resolution test would result.You may find, for example, that aconsole output transformer exhibitsa core saturation problem at normal levels only below 50 Hz. Insuch a case, a 40 Hz low tonewould be more appropo. A 6: 1 ratioof low to high would also increasethe sensitivity of our test to thisparticular defect.

Drifting bias balance in pushpull amplifiers and AGC amplifierscan cause unbalanced currents intheir output transformers whichmake them run much closer tosaturation at low frequencies thanyou might think. A 6: 1 IM test willpoint out this problem before itbecomes serious enough to be audible.

It's unfortunate that more equipment manufacturers don't give IMdistortion specs in the manuals sothat the equipment could be compared to its new performancestandard periodically. The best wayto solve this problem, however, is torun a standard SMPTE test on allnew equipment purchased and record the results along with the harmonic distortion specs in themanual.

42

POWERAMPLIFIER UNITU~'OER!ES! MIC. PREAMP

60HzONLY

6Cfü NULLSPEAKERPOWERAMPLIFIER !OUTPUT18000UTOFPHASE!

SCOPETOMONI!OR NUll

60Hz& 6kHz4,¡

LM. ANALYZER

Fig. 7 A method of testing speakers for IM distortion, The low toneis acoustically nulled out for a cleaner mic pickup.

Fig. 6 Typical test oftape dropout versus frequency.

Good practice dictates the use ofa high tone which is not an exactmultiple of the low tone, but formost practical applications it reallyis not critical. Care must be takennot to use tones which fall out ofthe bandpass of the IM meter'sfilters! If the IM meter used employs inductors in its filters, be sureto make tests in an area relativelyfree of hum fields to avoid modulation of the high frequency tone as itpasses through the high pass filter.

When testing equipment whichhas an IM specification pinneddown by the manufacturer, be careful to make your comparative IMtest with the same or nearly sametest frequencies, the same test signal ratio, and at the same outputlevel. The first two requirementsare easily met, but the third takessome thought.

When measuring the dual toneIM test signal, we must rememberthat the manufacturer's specs willprobably be for some RMS peakequivalent single tone sinusoidallevel. More than likely our testmeter will be an average respondingaudio voltmeter, or at best, a trueRMS meter. We must convert ourmeter level to its correspondingRMS peak equivalent single tonevalue. Actually, it's easier to dothings the other way around. Figure5 gives the conversion factors required. If, for example, an IM specis given for an output level of+LOdBm with a 4:1 test signalratio, our voltmeter should read

only about 81 percent of that valueto be equivalent.

Tape Equipment TestThe IM meter can also be a very

effective tool for tape recorder setup and maintenance. To understand why, it is helpful to reviewthe theory of an IM meter's internal operation. The high frequencytest tone is demodulated and themodulation components metered asdistortion. If the low tone is removed entirely, all that will remainis noise in a narrow band aroundthe high tone and any amplitudeinstability of the high tone.Tape dropout is one of the most

critical aspects of magnetic taperecording and is very easily measured with an IM meter; the lowfrequency tone is simply removed.The noise for lkHz bandwidth isusually negligible but the dropout,particularly at the very high end ofthe audio spectrum, is appreciable.

Figure 6 shows the results of atypical dropout test run. Note thatthe dropout increases as the frequency of the test tone increasesdue to the difficulty in maintainingintimate tape to head contact at theshorter wavelengths.

A simple and rapid procedure fortape and tape recorder performancechecks would be to set up forrecording at O dB with a low tohigh ratio of 4: 1 (SMPTE standard)using the IM meter's internal 60 Hzgenerator and an external variablefrequency audio generator for the




high tone. The range of frequenciesused for the high tone can extendfrom the lower limit of the meter'shigh pass filter to the upper limit ofthe instrument's frequency response, which is usually severaloctaves past the audible spectrum.A tape can be generated with thehigh tone covering the entire treblerange and then run again but withthe low tone shut off for a dropouttest. When played back through theIM meter, a very good indication ofsystem treble distortion can be obtained very quickly as no nullingadjustments are required.

When the second series of tonesrecorded without the low test toneappears, dropout can be measured.Harmonic distortion tests would bemuch more time consuming andless valid due to the restrictedbandwidth of a tape system. Probably the best quantative study of atape system would be harmonicdistortion tests at the lower frequencies and IM analysis for theupper half of the band includingthe dropout test just described. TheIM test procedure is also useful for

bias optimization as it allows arapid frequency vs. distortion measurement without the need for nulling type adjustments. The playbackamplifier can be monitored with theIM meter while the bias is adjustedfor minimum distortion in the audible band.

One of the best disc trackingmeasurement methods is an IMdistortion test employing a test record as the signal source. The CookLabs "Stereo IM Distortion TestSeries 300" and CBS Labs "SquareWave Testing and IM Test RecordSTR 110" are available.

If 600 Hz low tones are used onthe record you have, remember thatthis high a tone may fall on theskirt of your IM meter's low passfilter characteristic, thus reducingthe distortion indication. As amaintenance tool, however, the testwould still be just as useful as weare not interested in the absolutevalues of the distortion but in howthe distortion level compares with apreviously recorded value or howlow we can get it compared to how

(Continued on page 53)

FIVE MIXERAUDIO CONTROL

B-500 seriesthe B-501 monaural

$750the B-502 stereo

$1050B-503 dual channel

$950the McMartin

full choice line includesthe rack mount

ACCU-FIVEmini-console, andthe eight channel

B-800 seriesfor complete information

please contactthe Director of Sales

Dept. B-50

MCMartinMcMartin Industries Inc.

4500 South Seventy-sixth StreetOmaha. Nebraska 68127

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TWO NEW TESTINSTRUMENTS FORDIRECTIONAL ANTENNAS

FSM-1FIELD STRENGTH METER

DAM-1 DIGITALANTENNA MONITOR

Frequency: Any frequency inthe AM band; Phase Range: ±180°;

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Ratio Accuracy: ±2.0%; Ratio Resolution:±0.001; Input Impedance: 50 or 75 ohms

Delta's new Field Strength Meter and Digital Antenna Monitor will help keep your directional antennasystem within FCC specifications.

The DAM-1 Antenna Monitor meets the new FCCrequirements for remote control. It is a true digitalinstrument using the latest integrated circuit and TTLtechniques. Reads phase and true current ratio forup to six towers with different reference towers anddifferent powers for DA-2. Monitors for larger arraysavailable on special order.

Delta also offers remote panels and interface unitsfor controlling and reading the DAM-1 Phase Meterover multiconductor, two wire, UHF, or microwavecircuits with no reduction in accuracy.

The FSM-1 Field Strength Meter is smaller andmuch simpler to operate than other field strengthmeters because it is fixed tuned to your frequency byplug-in modules. If you have to check more thanone station, order the FSM-1 with additional frequency modules. For monitor point checks andextensive proof of performance work the FSM-1 willminimize errors and speed up field measurements.

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44 For More Details Circle (25) on Reply Card

Book Review(Continued from page 39)

Pulse, Switching CircuitsPulse & Switching Circuits, written by Harvey F.

Swearer is a complete, one-stop source of practicalpulse and switching circuit operation and applicationdata.

TV, computers, radar, telemetry, automation devices-practically every phase of electronics use pulse andswitching circuits in one way or another. And as technology continues to advance, it is increasingly important that every individual in electronics has a thoroughunderstanding of the principles and operation of pulseand switching circuitry. Whether the reader is atechnician, an engineer, a designer, a serious hobbyistor experimenter, he can update his knowledge with thisbook.

For those totally unfamiliar with pulse and switchingcircuitry, and for those who need to brush up, Chapter1 defines pulses-the basic definitions, nomenclature,harmonics, resonance, and the relationship betweentransistor switching and pulses. Pulse generator designand operation are covered in Chapter 2 - all basiccircuits: multivibrators, blocking oscillators, time-basegenerators, relaxation oscillators, Miller integrator,boot-strap generator, a unijunction transistor generator, saw-tooth generator, IC pulse generators, plusdetails on sync, timing, time delays, etc. In Chapter 3,response characteristics are explained in regard tonon-sine waves, transients, and non-rectangular waves.Also included are differentiation and integration, magnetic amplificiation, time-constant curves, and disertations on a variety of related subjects.

The book contains 256 pages, 11 chapters and over200 illustrations.

It is available through Tab Books, Blue RidgeSummit, Pa.


Solid State WorkbookWorkshop In Solid State was written by Harold E.

Ennes. The purpose of this book is to provide a rapid,practical, and effective transition from vacuum-tubecircuitry to solid-state circuitry. It is assumed that thestudent already has received basic electronics training.The material was originally developed for use intraining broadcast technicians. Therefore, broadcastcircuits and applications have been emphasized.However, the training is just as useful to students ofcommercial and industrial applications as to broadcastpersonnel.The 382 page book contains 17 Chapters.This book is available through Howard W. Sams &

Co., Inc., Indianapolis, Ind.For More Details Circle (93) on Reply Card




PEOPLE íl~•mBroadcast

Steven J. Sharp has been named manager of the"O-MOST" Products department, Signetics Corp ....Michael L. Ayers is the new director of public relationsfor Ampex Corp ....Western Union International, Inc.announced that Seth D. Blumenfeld has been electedassistant vice president for international relations ....P.Kim Packard has been appointed Operations Manager- Cathode Ray Tubes for the Electronic Tube Divisionof GTE Sylvania Inc.Charles Carl Conn has been named Video Cassette

Recorder sales specialist, Philips Broadcast EquipmentCorp ....3M Company has announced the appointmentof Daniel E. Denham as vice president of the newlyformed Recording Materials Group .... Sheldon L."Don" Kader has joined Molnar & Associates, Inc. asvice president .... Paradyne Corporation announced theappointment of John William Malamphy as salesmanager for their Washington, D.C. region ....Joseph A.Kjar has been appointed Executive Vice President forBonneville International Corp ....Clyde W. Price, president and general manager, WACT, Tuscaloosa, Ala.,has replaced James W. Wesley, Jr., vice president andgeneral manager, WIOD/WAIA, Miami, Fla., on theRadio Board of Directors of the National Associationof Broadcasters.Philip D. Costin has been named general manager of

WIOD-AM and Herbert R. Hirsch has been appointedgeneral manager of WAIA-FM, Cox BroadcastingCorp stations in Miami ....James W. Wesley, Jr. hasbeen named vice president and general manager ofAM Radio Station KFI, Los Angeles, recently acquiredby Cox Broadcasting Corp ....Roger D. Rice has beennamed West Coast Broadcast Vice President of CoxBroadcasting Corp., in addition to his responsibilitiesas vice president and general manager of KTVU (TV),San Francisco-Oakland ....Joseph P. Dwyer has beennamed controller and Elliot Nevins has been appointedprogram manager of AM Radio Station KFI, LosAngeles, Cox Broadcasting Corp.Richard T. Seifert has been named to the newly

created position of Manager of Applications Engineering for Western Digital Corp ....Koss Corp. (OTC), hasformed Koss Ltd., Canada, and named Greg Cornehlspresident of the wholly-owned subsidiary ...G. CurtisKline has been appointed Director of Marketing,Norelco Sound Systems, at Philips Broadcast Equipment Corp., ...Harris-Intertype Corp. has combinedthree divisions with eight plants in the U.S. andEngland into a new operating group, and appointedWilliam J. Stolze to head it in the newly created postof vice president-group executive ....John J. Navin hasbeen elected a vice president of International Telephone and Telegraph Corp .... ITT World Communi-


August, 1g73

"I jumped from tugboatto television

after I got myFirst Class FCC License"

What do you do with your off-duty hours if you work in the engineroom of a tugboat? Well, if you're Richard Kihn of Anahuac, Texas,you learnelectronicswith ClE.As he tells it: "Even before I finishedmy course, I passedmy First Class FCC License exam and landeda job as broadcast engineer with KFDM-TV in Beaumont, Texas.Then in my first year at KFDM, I finished my CIE course, earnedtwo raises and became a "two-car" family! Not bad for an extugboat hand! "I'd recommend Cleveland Institute of Electronicsto anybody interested in broadcasting."You need an FCC ticket to move ahead in broadcasting, and

five out of CIE's seven career courses prepareyou to "sit for" theGovernment FCCCommercial License exam. In a recent survey of787 CIE graduates, better than 9 out of 10 CIE grads passed theGovernment FCC License examinations. That's why ClE can offerthis famous Money-Back Warranty:When you complete any ClElicensing courseyou'll get your FCCLicense or be entitled to a full refund of all tuition paid. Thiswarranty is valid during the completion time allowed for yourcourse. You get your FCC License... or your money back.Send coupon below for FREE book. For your convenience, we

will try to have a representative call. If coupon is missing, write:Cleveland Institute of Electronics, Inc., 1776 E.17th St.. Cleveland,Ohio 44114.

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For More Details Circle (26) on Repfy Card 45



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cations announced the promotion of two of its staffmembers-Aina Liden and May Gilhooly-to keymanagerial positions in the International Telephoneand Telegraph Corp. subsidiary.Michael L. Nystrom and Kenneth M. Manke have

been appointed sales engineers for Nortronics Co.,Inc .... lvan D. Barton is now Southwest RegionalManager for Philips Broadcast Equipment Corp ....Theappointment of Charles W. Thierfelder as DivisionVice President, Manufacturing was announced byRCA....William G. Hartzell was appointed DivisionVice President, Engineering by RCA....Communications Technology Corp., Los Angeles, has appointedFred Miller as Regional Representative ....Henry J.Cauthen, president and general manager of the SouthCarolina ETV Network in Columbia, has been electedchairman of the Southern Educational Communications Assoc. (SECA)....Utah Electronics recently presented William Doyle the outstanding Rep Of TheYear Award during Utah's national sales meeting ....Howard D. Holst, managing director of WKNOTV/FM, was awarded a plaque of appreciation and aBelgium crystal trophy in a special presentation at the6th annual Southern Educational CommunicationsAssoc. (SECA) Conference .

CATVAnixter Bros., Inc., has named Robert E. McLlvane

to the new corporate position of vice president -sales ....TeleMation, Inc., announced the appointmentof four new executives to its staff. Named VicePresident of Finance was Walter Gnemi, with JayHubbell appointed to Manager of CATV Sales, VernPearson Manager of Broadcast Sales and William T."Bill" Blackwell as District Manager of TeleMationMidwest's Indianapolis branch office.Justo Caffi has been named general manager of

American Cable Television, Inc.,'s Napa Valley, Calif.CATV system ....John R. Dillon has joined the CableCommunications Division of Scientific-Atlanta, Inc. asMarketing Director .... Thomas P. Willett has beennamed director of marketing for Continental Cablevision, Inc ....E. C. Oldfield, Jr. has been appointedTreasurer for TeleCable Corp ....Royce R. Busey hasbeen named manager of Anixter-Pruzan's Southernoffice in Atlanta, Ga ....C-Cor Electronics, Inc. hasappointed George A. Livergood Sales Engineer and J.Joseph Howe Controller and Treasurer ....Robert T.Sample, formerly director of the Boulder County CableCommunications Project in Colorado, has joined thestaff of the Cable Television Information Center .

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~~IPRODUCTS(Usecircle number on readerservice card for further intorrnatlon)

FM Exciter-XmtrComplementing its FCC Type

Approved AM/FM/TV monitorsand broadcast audio console lines,McMartin has introduced its B-910FM Exciter and B-910T 10-WattEducational FM Broadcast Transmitter.

Frequency stability is insured byutilization of phase lock techniquesto establish the center frequency ofa direct-FM modulated oscillatoroperating at one-half the assignedfrequency. Low FM noise, -68 dBor better; AF distortion at 0.3percent and 0.5 dB frequencyresponse reflect the design excellence incorporated in the new B-900series.

With front panel access to fully-

shielded, individual plug-inmodules comprising the basicsystem, the exciter/transmitterpermits immediate conversion tostereo and/or SCA multiplex operating modes by simply insertingoptional modules: The B-110 StereoGenerator or B-113 SCA Generator.

Automatic protective circuitryprovides indication of the phaselock condition, plus carrier interruption if the center frequencyshould shift 100 kHz or more fromthe assigned operating frequency.

Metering of all supply and phaselock control voltages, relative RFoutput and semipeak audio inputvoltages is provided.For More Details Circle (50) on Reply Card

. Gated CompressorShure Brothers Inc., has an

nounced the first professionalbroadcast component combining athree input mixer with 600-0hmline output and a true "hands-free"gain riding compressor in one, selfcontained, portable unit.

Called the SE30 Gated Compressor/Mixer, the new Shureproduct is designed especially forbroadcasting and sound recordingapplications both in the studio andon location.The SE30 compressor is adjust


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It's not easy to improve on a product like the DYNA-MOD,which has long been the standard of the industry ... manymanufacturers have tried and failed. But DYNA-MOD 11is a step forward; it reflects improvement over its predecessor in styling, operator convenience and performance.

The basic DYNA-MOD 11 accepts separate audio andvideo inputs from which it generates a broadcast qualityVHF television signal on a specified channel. It containsa sideband response filter and output amplifier whichassure quality performance in adjacent-channel colorsystems without the addition of external filters. Anoptional envelope-delay correction filter is also available.Maximum RF output is 500,000 microvolts with a second

output providing a 1O DB reduction. A switch-selectableattenuator allows attenuation of either output in 1 DBincrements over a 10 DB range. A third RF output is provided for monitoring purposes. Visual and aural percentages of modulation are easily measured with a meterlocated on the front panel. Overall appearance of the unithas been styled to match our DYNA-TUNE Demodulator.

Shouldn't your next modulator be a DYNA-MOD 11?Write or call today for literature and prices.

DYNAIR ELECTRONICS,INC. ~6360 Federal Blvd., San Diego, Calif. 92114 1 ' 'Telephone: (7141 582-9211

Augus:, 1973For More Details Circle (17) on Reply Card

47



Simpleanswer toa

•pressingproblem

"UNISWITCH." It lets you dothose bright but simple switchingjobs without expensive, complicatedlighting devices.This low-cost,momentary pushbutton illuminatedswitch hasa l·A circuit in only11/16" square panel space.If you want to look expensive (butstay low-cost and un-complicated)the illuminated "Uniswitcn" isavailable in color. Lots of it. Red,white, blue, green and yellow arestandard. You get brilliant frontand side lighting, clearly visible ineither high or lowambientenvironment. Light is evenlydiffused throughout visible buttonsurfaces. Lighting is corcstantandindependent of switching action.Front of panel relamping.And installation is low-cost. Justsnap "Uniswitch" in, notoolsneeded.The low-silhouette bezelserves as an escutcheon plate.Terminals are screw and/or solder.Silver plated contacts rated at250 ma., 30 watts, A.C.non inductive load.Don't over-designyour next panel.Get your free EngineeringSpecification File on illuminatedand non-illuminated (for verylow-cost application) "Uniswitch"Switches. Contact your localSwitchcraft representative, or writeSwitchcraft, Inc., 5555 N. ElstonAvenue, Chicago, Illinois 60630.

~®

For More Details Circle (30) on Reply Gard

~fill PRODUCTS(Continued from page 47)

able to input requirements within a40 dB range. Once the compressoris set, it virtually rides gain automatically. A unique Gated MemoryCircuit "holds" compression levelwhen input signals stop or dropbelow a certain threshold, therebyeliminating the "pumping effect"normally associated with conventional audio compressors. Whendesired program material returns,the "hold" is automatically releasedand the compressor goes back intoaction. This feature is especiallyuseful during live broadcasting ofnews and sports events to eliminatecrowd noise build-up when theannouncer stops talking.

Compression is accomplished "inthe field" before the signal enterstelephone lines or voice couplers,the signal-to-noise ratio is optimized and, as a result, offeringimproved phone line transmissionand program quality.


In studio use, the SE30 ridesgain on any type of programmaterial, freeing the operator forother duties. The Gated MemoryCircuit eliminates the rush of noiseduring pauses in speech and at theend of records and tapes.For More Details Circle (51) on Reply Gard

50kW FMTransmitter

A new high power FM broadcasttransmitter providing a high degreeof redundancy and solid state reliability has been introduced byAmerican Electronic Laboratories,Inc. (AEL).

The new model FM-25/25KDconsists of two AEL· FM-25KD(2SkW) ·FM transmitter and a hybrid combiner, providing a standard operational output of 40kWand total capability of SOkW withplenty of power ·reserve.The basic configuration is com

prised of a control and interfacecabinet placed between the twotransmitter cabinets. The hybridcombiner, available in 3-1/8",4-3/8" or 6-1/8" line depending onoutput power requirements, can beexternally mounted when stationlayout permits. Customized patching and switching functions areavailable.The unit's hybrid combiner ac

cepts, combines and delivers theoutputs of both transmitters to theantenna. When one transmitter isshut down, the combiner operatesas a power divider, delivering halfof the operating transmitter's powerto the antenna and dissipating therest to the reject load connected tothe combiner. Since a high degreeof isolation is maintained betweenthe transmitters, service may beperformed on the off unit.The center cabinet of Model

25/25KD houses metering and control functions, as well as the interface for connection to remote control and monitoring. The exciter,buffer and phasing controls, inaddition to meters for combiner




functions, for power readings andindividual transmitter start, stopand plate voltage control are placedhere.

AEL's Model 2202A Exciter provides drive to a solid state dualbuffer amplifier, the outputs ofwhich provide excitation to the25kW amplifiers. Each amplifier isconnected through its harmonic filter to the inputs of the hybridcombiner. Featuring a very highdegree of phase stability and providing conservative operation, eachamplifier contains a 4CX1000Kdriver stage and 3CX1SOOOA7grounded grid power amplifier.For More Details Circle (52) on Reply Card

Dropout Compensator3M Company now has available

their new color dropout compensator (they call it the DOC). Thenew unit works with any quad VTRand it replaces lost video information, in color or monochrome,with correct video.

The unit is designed to eliminatecolor flashing. And servo lock andcolor lock are automatically maintained, allowing full color interlaceand VTR stability even throughmulti-generation dubs.

Luminance and color are processed through separate delay lines,with color phase-inverted to achievecolor interlace with the stored signal. Comes with adjustable dropoutreplacement threshold, RF AGC tomaintain level set, and a built-indropout simulator for alignmentwithout a test tape.For More Details Circle (53) on Reply Card

Mini-PortableScope

Introduction of the Vu-dataModel PS910 has extended thefeasibility of on-site field serviceand maintenance by providing DC-20MHz wide-band operation in aminiature, line- or battery-operated,portable oscilloscope. Truly a"mini-portable" because of itsunusually small size and weight (1%H x 81/2 W x 12 D, seven pounds)the PS910A can go in a tool case orin the slimmest attache case.

Designed mainly for the engineerwho travels the PS910A alsooperates from the AC line and

August, 1973

mounts directly in existing equipment to provide full-scale monitoring capability in minimum panelspace. All controls are located onthe front panel.

Batteries are entirely internal andmay be nickel-cadmium, alkaline oreven flashlight cells. Rechargingcircuitry is integral and batteriesare electronically protected againstover-discharge. Up to five hoursoperation can be obtained fromnickel-cadmium cells. For More Details Circle (54) on Reply Card

Audio ConsolesBroadcast Electronics now has

available four new audio consoles.These consoles offer high and lowlevel pre amps for each channeland electronic switching of inputchannels via FET's.

Offered in stereo and monomodels, these consoles provide individual program, audition, monitor,cue and headphone amplifiers, plusmono mixdown amps (stereo models). They give identical programand audition output channels for

dual console capability. Ladder attenuators are used, and carbon potsare available at lower cost in monomodels.

Construction is solid statethroughout, with modular, plug-incircuitry. Broadcast Electronicssuggests that all requests for further information be sent to: Broadcast Electronics, 8810 BrookvilleRoad, Silver Spring, Maryland,20910.


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IPSTHE MOA- I B IS A SELF-CONTAINED RACK MOUNT, ORTABLE TOP UNIT, INTENDEDTO SUPPLY DRIVE MOTOR

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~NPRODUCTS(Continued from page 49)

ProductionSwitching System

American Data Corporation, anAIRPAX Company, has recentlyreleased their all new Model 556Production Switching System. Thesystem is a real "mini" but boasts"maxi" features.The standard 556 has ten com

posite or non-composite inputs,which includes blackburst, and fourbusses. The special effects systemincorporates the twelve "most used"wipe patterns, including a circle. A"joystick" positioner with a spotlight effect and a three input downstream keyer are also standard.

Downstream keying enables theoperator to key without defeatingthe pattern generator so that special effects can be done behind anykey including a chroma key. Thekeyer also includes both "Wipe"and "Blink" Key features and color

FLUTTERBARRECONDITIONING

matting of monochrome keys. Reentry of Effects-Key into Mix allowsthe operator to Mix into or from anEffect or Key, or Key on top of anEffect.

Other standard features of the556 system are Program and Preview output switching, a ColorBackground - Blackhurst - ColorMatte generator, a processing amplifier on the program output channel, momentary illuminated barrierswitches, and provisions for anRGB chroma keyer.For More Details Circle (55) on Reply Card

6 kW DimmerSystem

Berkey Colortran Inc., a divisionof Berkey Photo, Inc., has an-

nounced their new 6k W DimmerPack System. The "Big Brother" ofthe 2.4kW and 3.6kW DimmerPack Systems, features 6-6kWDimmers in a housing 20" wide x14" high and 21.5" in depth.The Control Pack is a two-scene

preset with individual channelmode selections of independent,preset and off. A master of eachscene is provided, along with tracking L.E.D.'s. The Master Pack provides mastering control for up to 20control packs. It features A-Bfaders, an Independent Master andGrandmaster.The Dimmer Pack weighs only

140 lbs. and may be stacked on acastered base for portable usage.The 6kW Dimmer Pack featuresplug-in circuitry, unique phasechange block, fully magnetic circuitbreakers, and high quality filtering.Systems may be combined as building blocks up to 120 dimmers, andmay be mixed with 2.4kW and/or3.6kW Dimmer Packs. Availablewith a wide choice of output receptacles or a terminal input/output

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versions.Portable models utilize color

coded Camlok connectors for powerhandling. All controls cables areequiped with positive, cannon typeconnectors.For More Details Circle (56) on Reply Card

Extended PlayReproducer

A new, second generation, Scullyextended play reproducer designedto meet the· demanding requirements of the broadcast industry isnow available. Built to exactingspecifications the LJ-10 offersunique features designed to improve performance and simplifymaintenance.

Tone sensing circuitry and endof-music overlap control are builtinto the LJ-10. No longer is aperipheral unit required to accomplish these functions. This reducesa broadcaster's overall costs, savesspace and increases reliability.A closed-loop tape drive signifi

cantly affects wow and flutter (3¥.iips). Tape is now pulled, ratherthan pushed and pulled, enhancingreproduction quality. While thecomputer industry has used asimilar drive unit for many years, itis new to the broadcast industry.For More Details Circle (57) on Reply Card

Solid StateColor Camera

The Philips LDK 5 is the first ofa completely new generation ofcolor cameras. Integrated circuitryand a new design approach mean

For More Details Circle (36) on Reply CardAugust, 1973

that all video processing is doneright in the camera itself. Many ofthe usu-al CC.U. functions havebeen incorporated in the camerahead.The operating controls in the

base station send their commandsignals in a digital code form,requiring only a simple two-waylink such as a telephone connectionor radio transceiver. In fact up tofour cameras can be controlled overone telephone line. An 8 mm. triaxial cable is all that is required toconnect camera and base station. Ifthe power supply is moved next tothe camera the link need'.only be aco-axial cable. This all adds lip themost flexible camera system everproduced.

Many other factors also contribute to the operational flexibility.Camera control settings are automatically retained in the camerahead by the built-in digitalmemory, even when disconnectedthey are maintained by a rechargeable cell providing sufficient outputfor several days. This now allowscamera sharing to become a practical reality; so long as there is anavailable base station in eachstudio, or O.B. van, any LDK 5camera can be ready in just thetime it takes to reconnect.

The base station consists of threeindependent and self-containedunits which can be positionedwherever preferred. As the wiringbetween these units is also verymuch simplified, the result is thatnew studios will require far lesswiring than previously and will bemore flexible in operation.For More Details Circle (58) on Reply Card

CharacterGenerator

Datavision's Model D-2400character generator offers broadcasters exceptional versatility sinceit allows users to present two different page displays simultaneously,with only one machine. This makesit possible to use one title on-airwhile preparing, changing or previewing three additional titles onthe unit's keyboard.

Standard D-2400 features include: large, easily read characters,32 scan lines high; four-page, two


Accessoriesa la earl• Taoe cartridges• cartridge Racks• cartridge WindersEverything you need to imp rove and upgrade your tape cartridge operations isnow available from Broadcast Electronics. Inc.

Rack 'emUDSpotmaster cartridgeracks come in ninedifferent models.holding 20. 25, 40,72, 100 and 200 cartridges. You can getfree-standing floor racks table topracks lazy susan racks wall-mounted racks even rack-mountedracks. Our catalog shows all of them.

Wind 'emUDOur handyTP-1B cart ridge winder letsyou create your owncarts - any length.No need to restrictyour cart operationto stock sizes or to tie up your conventional tape equipment loading cartridges.Optional tape timer provides precise-lathe-second calibration for making exactlength tapes.

... and01ay on IThe best carts areAudiopak and Fidelipac. We stock themin all sizes for immediate delivery, no minimum order.Empty carts, too, plus DL carts (forSpotmaster delay machines). alignmentcarts, bulk tape, tape tags, automaticsplice finders. demagnetizers, splicersand everything else you need to enjoythe pushbutton convenience of moderntape cartridge broadcasting. It's all waiting for you from the world leaderin tape cartridge systems and equipment.Call or write today for full information.

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51



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Dual function utility amp. Inputs formic and/or line - 600 ohm balancedoutputs - mic input, -65 dbfor -4 dbm out - j-20 dbm outmax.- ·0.5db response,1O Hz-20Khz- 0.1% or lessdist. - Internalpower supply - Tabletop/bracketmount. MLA-2, Stereo/Dual Mono.MLA-1,Mono.Shippingweight.4 lbs.

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One third the cost of comparableunits.Six 600ohmbalancedoutputs- Balancedbridging input - 26 dbgain - -,.20dbm out max.- Inputlevel control - 0.1% or lessdist. -=0.5 db response.1O Hz-20Khz-Internal power supply - Tabletop/bracket mount - Shipping weight,4 lbs.

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Precision winding without guesswork. Dial in the minuteand/o- seconds desired, throw switch to run.That's it' The exact amount of tapeis fed onto the cartridge hub to thesecond.and shuts off automatically.No waiting around, no guessworkand 1 sec. accuracy. Also has exclusive torsion control for propertape pack and winding of variouscart hub sizes. TTL digital controlcircuitry. Shipping weight, 30 lbs.

RAMKO RESEARCH3516-BLaGrandeBlvd.JP.O.Box6031Sacramento,Calif. 95860(916)392-2100


~NPRODUCTS(Continued from page 51)

channel display capability; one-rowhorizontal crawl; full cursor editing; 8 rows of display (16 characterseach) per page; and external titlestorage, using standard audio recording equipment.The D-2400 provides up to 32

one-row title storage, with randomretrieval and display, one row at atime, in the lower one-third of thepicture area. The D-2400 also permits single or multi-row title displayanywhere in the picture area, andsingle line horizontal crawl displayat the bottom of the picture. TheDatavision D-2400 can interfacewith both teletype and computersystems to provide instant displaycapability of fast breaking events.For More Details Circle (59) on Reply Card

Portable TVCassette System

An economical and portable TVcassette system that can be easilyoperated by people totally unfamiliar with cassette equipment hasjust been introduced by VideodeticsCorp.Called the VIDEOSETTE™

Communications System, PortableModel, the lightweight unit consistsof a color video cassette player anda 12-inch color receiver. The playeraccommodates standard 3/4-inchtapes and utilizes the popular UMATIC format.

Unlike other cassette systems, nomanual adjustments are required.The operator just inserts a prerecorded tape into the player, andthe player and rnonitor turn onautomatically. At the conclusion ofthe tape, or a predeterminedposition, the tape rewinds to theSTART position and turns itselfoff. Monitor fine tuning is alsoautomatic.Totally automatic operation en

ables the instructor to train a student without supervision and without being present; thus he cangreatly increase his productivity.The new Portable VIDEOSETTE

unit also features automatic reset ofthe tape counter, built-in stereoamplifier, automatic repeat forcontinuous programming, built-in

volume control, and internal phonejacks for head phones to accomodate individual viewing.For More Details Circle (60) on Reply Card

DigitalMultimeter

A new multimeter designed tomeet the needs of users throughoutscience, technology, and industryhas been introduced by the JohnFluke Company, Seattle, Washington.

Featuring a basic accuracy of0.1%. The new Fluke 8000A measures, in 26 ranges, AC and DCvoltages from 100 microvolts to1200 volts, AC and DC currentsfrom 100 nanoamps to 2 amperesand resistance from 100 milliohmsto 20 megohms. All instruments areguaranteed to meet specificationsfor one year.

According to the manufacturer,the Fluke 8000A is the first instrument to use both analog and digitallarge scale integration. The twochips used, equivalent to over 3,000circuit elements, help reduce theparts count to about one-third thatof typical 3-112 digit voltmeters.Because of the low parts count andLSI design the company says that itexpects high reliability.For More Details Circle (61) on Reply Card

Portable TVProduction Center

A portable television productioncenter designed for video-tapeoperations for smaller studios hasbeen introduced by GBC ClosedCircuit TV Corp., 74 Fifth Avenue,New York City.The GBC "Mini Console" is a

complete television productioncenter in one portable unit. Included is a special effects generatorwhich makes it possible to switch orfade from one camera to the other;to super-impose to six differentwipes (horizontal, vertical and thefour corners); and to do lapses anddissolves.

The GBC "Mini Console" accepts inputs from three differentcameras and a video-tape recorder.The unit also features a highquality four input audio mixer andthree 5" monitors. It is deliveredcomplete and ready to plug in.For More Details Circle (62) on Reply Card




IM Testing(Continued from page 43)

high it was. And boy can it behigh!

You can imagine the effect of alow tone on a stylus attempting totrack 6 or 7 kHz at the same time.A defective stylus, pickup or tonearm tracking error will quickly generate 10 percent distortion. Styluspressure can also be set as a function of IM, thus insuring maximumtracking performance with no morethan necessary record wear.

Monitor Speaker AnalysisOne of the more sophisticated

and interesting applications of IMtesting is monitor speaker analysis.Harmonic distortion data is usuallycontained in the manufacturer'sspecs .. but IM data frequently isnot. Multi-driver systems usuallyare less prone to IM for obviousreasons. The most likely offender isa single driver of small diameterbecause of the large cone excursions and the fact that the higherfrequencies must suffer from thenon-linearity that the voice coilencounters while attempting to follow a large low note.

This is a generality. Small singledriver systems with very large magnetic circuits can be quite good.Conversely a three-driver stystemdoesn't guarantee low IM, but, as ageneral case it does hold true.

Measuring this distortion is notdifficult, but the limitation of theelectro-acoustical link must betaken into account. A typical testsetup is shown in Figure 7. Careshould be taken to choose a microphone that exhibits inherently lowIM like a good pressure sensitivecondenser mic.

Room reflection can both assistand confuse. Reflections causingcancellations near the high frequency test tone should be avoidedby sweeping the frequency of thehigh test tone to 500 Hz each sideof center to be sure that the microphone is not in a null for one ofthose frequencies. If, however, themicrophone can be placed in a nullfor the low frequency test tone.thenthe probability of microphone induced IM in your readings is allbut eliminated.

If an on-axis reflection cannot be

August, 1973

arranged, an additional speakermay be used to produce a null spotat the low tone frequency. If thelow tone cannot be acousticallynulled and the microphone musthandle both tones, move the micfurther from the speaker and remeasure the distortion. If it doesnot decrease, the test is still validbecause the distortion measured isin the speaker, its drive level havingremained constant. While measuring monitor speaker distortion mayat first seem a bit far out; whowould purchase a console with amonitor amplifier that has 8 percent distortion?

One of the biggest surprises to abroadcast engineer making IM distortion measurements for the firsttime is the higher percent level ofIM than harmonic distortion thatusually exists in the same system. Ifyour FM rig is good for 0.5 percentharmonic distortion at 400 Hz,don't be too surprised if the IM isover I percent. There is no directrelationship between the numericalvalues of IM and harmonic distortion in the same system, but IMseems to relate more to listeningfatigue than harmonic distortion.Being harmonically related to amusical note seems to endear a

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D JENSEN TOOLS~ 4117 N. 44th Street, Phocn1•, Ariz. 85018

Cl: =For More Details Circle (41) on Reply Gard

AutomaticSplice Finder

Cart EraserIf you record over tape spl ces, you canmiss vital words or distort your audio.And now you can stop wasting man-hourssearching for those elusive splices. Justinsert any NAB tape cartridge into theSpotmaster SFE-1. It starts automatically,finds the splice and ejects the cart. Easy,foolproof operation; does not require apre-recorded signal. Built-in cart eraserfor added convenience.Other Spotmaster degaussing aids: Heavy.duty 300C table-top bulk eraser, handlesup to 1"-wide, 1OV2 "-dia. video tape reels

Model 200C hand-held pushbuttonbulk eraser . Tape head demagnetizerfor reel and cart machines.Contact us today for details.

BROADCAST ELECTRONICS, INC.---A Filmways Company---8810 Brookville Rd., Silver Spring. Md. 20910

(301) 588-4983 • TWX 710-825-0432

distortion component to the listener's ear, where the closely jumbledIM "no goods" cause an irritatingfuzziness. Since the IM figures fora piece of equipment don't usuallylook as good as the harmonic data,some manufacturers don't printsuch test results even if they haverun them, no matter how importantor informative they may be.

Perhaps if more engineers wouldinquire about IM performance ofnew or existing equipment, manufacturers would be more inclined topublish this spec. We wish to thankCrown International for their assistance in obtaining technical materials for this article. O

BibliographyCallendar, M. V. and S. Matthews"Relations Between Amplitudes ofHarmonics and IntermodulationFrequencies" Electronic Eng. (June1951)

Shorter, D. E. L. "The Influence ofHigh Order Products on Nonlinear Distortion" ElectronicsEngineering (April 1950)

W. l. Warren and W. R. Hewlett"An Analysis of the Intermodulation Method of Distortion Measurement" Proc. LR.E. (April 1948)

D. E. O'N. Waddington "Intermodulation Distortion Measuremerit" Jour. of Aud. Eng. Soc. (July1964)

Harold E. Ennes "AM-FM Broadcast Maintenance" Broadcast Engineering Notebook Howard W. SamsVol. 3

H. E. Roy "l.M. Distortion Analysisas Applied to Disk Recording andReproducing Equipment" Proc.LR.E. (Oct. 1947)

AM·RFamplifierTBM-8800

$4851.0 mV senstttvttye

excellent selectivity•rni ruma!e

signal degradationremote/local•

high-lowpower operation

adjustable•separate outputs

MClU~artin McMartin Industries Inc., 4500 South Seventy-sixth StreetOmaha. Nebraska 68127 Phone (402) 331-2000 Telex 048-485

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PllFESSIDUl $~&$VII JAMIS

CONSULTIN& RADIO EN61NEUSAppllc•tlons •nd Fleld En9lnurln9

145 Color•do llvd.Phone: IAru Code JOJ) lll-55'2

DENVER, COLORADO 80206Member AFCCE

SMITH and POWSTENKO

Broadcasting and TelecommunicationsConsultants

2000 N Street, N.W.Washington, D.C. 20036

(202) 293-7742

CAMllUDGE CRYSTALSPRECISION FREQUENCYMEASURING SEltYICI

SPECIALISTS FOR AM-l'M-TV445 Concord Ave. Phone 876-2110

C•mbrldqe. Mus. 021lt

RALPH E. EVANS ASSOCIATESConsultlnq ••dio Enqinur1AM . FM - TV· CATV· ITFS3500 North Shorm•n llvd.

MILWAUKEE, WISCONSIN 53218Phone: 414-442-421O

CHU ASSOCIATES, INC.Telecommunications Division

AM-FM-TV-CATVApplications- Facilities Planning

Field Surveys and ProofsAppraisals

800 FeslerSt., ElCajon,Ca.92020(714) 442-9459

TWX910 331 1178

SESCO, Inc.47 NICHOLS AVENUE

P. O. BOX 518

(206) 378-2137

FRIDAY HARBOR,WASHINGTON, 98250

Moving?Send Your Change

Of Address To:Broadcast Engineering

1014 WyandotteKansas City, Mo. 64105




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Each initial or abbreviation counts a full word.Upper cave words. JOc each.

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For ach on which replies arc sent to ll.\ forlorward ing. there ¡_... an additional charge of $2.00to cover dcpurtmcnt number. ct e.. which is printedin advertising copy. and processing of replies.

Clavvificd columnv arc not open to advertising of'any products regularly produced by manufacturersu n levv U.\Cd and no longer owned by themanufacturer or a distributor.

TRAININGPASS FCC EXAMS with Ameco books. Each bookcontains FCC questions plus simplified answersplus FCC.type exams and answers. 3rd class 75c.2nd class $2.25. ht class SI.SO. Free catalog.Ameen Publishing . .Jl4G Hillside Ave .. WillistonPark. N.Y. 115%. 8-72-tf

FIRST PllONE through 1;1pc recorded \e\.\Oll\ ath o ruc plu v one v cc k pcrs on a l i11 -, t ruct io n inWa •..liington. DC. Atlanta. Bovton . Detroit. NewOrl1.:;111v. Minncapoli v. Sc.u tlc. Denver. Portl.md .l.o-, Angl'IL'\. Proven rcvult v. Our l Zt h year1ead1i11g FCC liccuvc courvcs Bob Johnson Hadiol.iccu-v Prcpar.u iou. IOhOD Duncan. ManhattanHcavh. Calif. 802hh. l'ho11L' 21.\-.l7lJ-44hl. 1-hlJ-tf

PASS FCC lir\t and vecuud t·l~I\.\ exams with new21 lcv-uu . 4.)()-pagc cour-,c. St art s wit h hnvicdLTtriL·i1y. Owr 600 FCC-type. multiple-chokeqt1L'\Iiun-, and vam pk cxam-, inducted. No previoust cchn icel k nowlcdgv required. Commcrciul RndioOpvrat or Theory Co urvc. #15-01. 011ly $5.95.AnlLTO Puhl i•..hi11g . .114G Hillvid c Ave .. WilliviouPark . N.Y. 115%. 8-72-tf

EARN ELECTRONICS DEGREE, main ly hycorrcvpo n dc ncc. F.C.C. licc nvc preparation ineluded at your option. Accredited hy J\cneditingCo111111i\\it111 of NHS('. G.I. Bill .upprovcd. Freehrorh urc . Write: Dean. Grantham School ofF11gi11ccri11g. 1505 N. w c stcrn . Hollywood. Califor-11i" 'KK)27. 8-72-tf

FCC RADIO TELEPHONE OPERATORSLICENSE in six weeks. Classes (day & evening) inAtlanta. Dallas. Denver. Ft. Worth. Hartford,Houston. Memphis. Nashville. New Orleans.Oklahoma City". and San Antonio. For informationcontact Elkins Institute. 2727 Inwood Road,Dallas. Texas 75235. 214-357-4001. 5-73-tf

SERVICESCRYSTAL & MONITOR SERVICE. Frequencychu nuc. repair or r c p lacc m c n t of oven t y p ehro:ick:i\I l'l')'.\t~d'.'.. J\\.\11 trcqucnvy change andrccalihtatiun or repair of /\M Ircquc ncy rnouitorv.ami 11-P FM 111011it1H'\. Fa\t service at rcavonuhlcpricc-; JO yea rs cx pcricncc! Call or write: EidsonElectronic Co. Box %. Temple. Tx. 7h501 Pho.817 77.l-.l'K)l 9-70-tf

CAHTRIDGES SPOTLESSLY CLEANED,HE BUILT AND HE LOADED with Scotch IG7.Like new al approximately half price. Also,B~:ST PRICES anywhere on new FlllELIPACcarts, :JM professional Lape and other studiosupplies. YOUR ORDEH IS YOUH CHAl{(;EACCOUNT' Full guaranle<'. FREE CATALOCUE. Lauderdale Electronic Labs. lfi S.W.13th Street. Fl. l.audr-rd alc. Fla. :¡:¡:¡I !i l:!O!iJ5:l!i-0478. 4-7:!-nt

August, 1973

WANTEDWANTED: All vu rplu x hr o a d cas t c q uip mc n tcvpec ia ll y clean J\.M. & F.M. t r a n s ruittc rv.t'11111r;1c1or\. capacitors. Sur pluss Equipment Sulcv.2 Th111·1K·lilfr Pk. Dr. Unit 28 Toronto 17. Ont:Canada. 1-7.1-tf

TUBES WANTED-All types-CeCo 2115 AvenueX. Brooklyn. N.Y. 11235. 212-646-6300-Anytime.

7-73-12X

EQUIPMENT FOR SALE

SURPLUS AUDIO PATCH PANELS. All Standard Configurations. Gulf Telephone & Electronics.Inc .. !'.O.Box 42130. Houston. Texas 77042. 7-72-tf

MOTORS FOR SPOTMASTERSl·:W P:t¡l\ hy.\terc\is synchrouous motor HSZ

20.S0-4-470[) as uxcd in series 400 and 500111;1L'lli11l'\. Pr ice $39.00 each prepaid. while they1;i,1. 90 d ay warranty. Terms check with orderonly. no COIY.\. Not rL'l'0111111e1Htcd for Tupccastcr\1..'l'iL'\ h()() 1.H' 70().

TA l'ITASTEK TCM. INC.. Box 662.Rockville. Maryland 20851

1-72-TF

"NEW & USED TOWERS, Buy. Sell or Trade.Frn·1. Ground wire 85L' lh. Bill Angle. 919-752-.1040. Bux 55. Grvcuviflc. N.C. 278.l4." 2-71 ·tf

ONE STOP for all your p ro lcs sio na l audiorvquircrncntv. Bottom line oriented. F. T. C.HrL'\\ cr (\1111 pa ny. P. O. Box 805 7. Pensacola.Flnrida .12505. 7-71-tf

QUALITY AUDIO CONSOLES arc our specialty.M1.Hkr11 -,1yli11g with vlidc potcntiornctcrx and..voft" audio \\\·i1rhing. Wl· manufacture 8 standard vuuvolcv at very competitive prices. However.v cT! ru a u u f'act urc ;i cuvt urn syx t c m to your'Pl'l'ilkatirn1\ if you prefer. Al\o plug-in audioruodulc-, including divttihut iun amplifiers. pre.uupliticrv. monitor amplifiers. ctr. Write or phonefor pricing and \pl·cili...-;1tions. SYSTEMS EN·GINEERING COMAPNY, P.O. Box 49224. Atkuua. üa .. 10.124. 404-482-2446. 2-7.J- l 2x

HEL.IAX-STYROFLEX. Large stock-bargain\H'il'l'\-IL'\ted und ccrt ilicd. Writl' for price andvtcu'k li\h. Sicrru Wcstcru Elcctric, Box 2J872.Oak land. Calif. 94'12.l. Telephone (415) 8J2-JS27.

¡.73-tf

NATIONAL TAPE CARTRIDGE SERVICESPECIAL Pressure Sensitive Labels. Fits All Cartridges. Comes in 5 Colors. Write for FREESample. MASTERTONE COMPANY. 1105 MapleWest Des Moines, Iowa 50265 515-274-2551 8-73-tf

NATIONAL TAPE CARTRIDGE SERVICECARTRIDGES RECONDITIONED - NEW TAPE12 Years Experienced Personnel. Write for newand reconditioned price sheet. Mastertone Co.,1105 Maple. Dept. B-E I, West Des Moines, Iowa515-274-2551 8-73-tf

APECO VIDEO VALUES: Below O.E.M.importers cost. ..a complete product line close out,including cameras, monitors and accessories. Ordernew and used equipment in any quantity while thesupply lasts. Sample Bargains: 9" Monitor: Was$140.00 ... Now $95.00. 4-Position Passive Switcher:Was $35.00 Now $20.00. Viewfinder Camera:Was $220.00 Now $140.00. 25MM f/1.4 Lens:Was $40.50 Now $30.00. Call for more Informa-tion: Apeco Video Systems, 2100 Dempster Street,Evanston. Illinois 60204. 312/869-9000 8-73-lt

AMPEX 7500 COLOR VIDEO TAPERECORDER - mint condition - spare head.$525.00. Stan Nazimek, 506 Mount ProspectAvenue; Clifton, New Jersey 07012. 8-73-lt

EQUIPMENT FOR SALE CONT.

SURPLUS MICA ANO VACUUM TRANSMITTING CAPACITORS. Large stock; immediatedelivery. Price lists on request. SURCOMASSOCIATES, 1147 Venice Blvd .. Los Angeles,Ca. soots (213) 382-6985. 5-73-121

BROADCAST TOWER for sale. 200' best offeraccepted. Contact Mel Gleason, Box 531, York.Nebraska 6846 7 8- 73-1 t

COMPLETE UHF IZKW TV Transmitter andsupporting gear for sale. RCA TTU 12B, 760' of 6118 transmission line. CH 18 TFU24DL antenna,600' tower. misc other equipment. Call 317-463-3516 Bob Hardie Chief Engineer or write P.O. Box18. Lafayette. INDIANA 47902. 8- 73-1 t

RCA 'ITU12A transmitter. On Channel 33 but canbe retuned for other frequencies. Including: I TTUI B Driver; 2 12 KW power amplifiers with powersupply; I lilterplexer, I heat exchanger with sparewater coil; I set of spare cavities for all stages; Iset of miscellaneous parts and tubes. This transmitter was recently removed from service and isavailable immediately. 600 ft. 6 1/8" EIA boltflange type transmission line. Used and in goodcondition. Contact A. W. Taylor, WYTV, Inc.,Youngstown. Ohio 216-783-2930. 8-73-lt

SCHAFER 800 AUTOMATIONSTEREOSYSTEM for sale. Good/ExcellentMake Offer. (405) 478-0444.

condition.8-73-lt

TELEX STEREO TAPE DECKS - 1048 and 1024in mint condition. Purchased for business thatnever developed. Same decks used by NASA forrecording moon flights. Also Universal AudioLimiting Amplifier 1176 LN. Must sell. ContactHerbert Benton. Jr .. 607 Georgetown Rd .. Cleveland, Tenn. 37311. Phone 615-479-4094 after 9PM. 8-73-lt

CARTRIDGE TAPE EQUIPMENT-Rebuilt. Newpaint. heads. flywheel. pressure roller. belts. etc.Spotlessly clean and thoroughly tested. 30 daymoney-back guarantee, 90 day warranty. Alsocontact us for possible discounts on new equipmentand accessories. AUTOOYNE. Box 1004, Rockville. Maryland 20850. (3011762-7626). 8-73-tf

AM RADIO STATION 5,000 KW Eastern Arizona- substantial cash. KHIL. Willcox. Arizona, 384-2780 - 384-2367 8-73-41

TWO, GENERAL ELECTRIC PE-250 ColorCamera Chains less mounting and monitoringequipment. $9000 each. WKNO-TV % MemphisState University. Box 80,000, Memphis, Tennessee38152. (901) 458-2521. 8-73-lt

BUILD YOUR OWN TV ANO RADIO PRODUCTION EQUIPMENT. Eas y. inexpensive.(mostly IC). Plans or kits: Special EffectsGenerator. Automatic Logger. Vertical IntervalVideo Switcher. Solid State Lighting Board. PresetAudio-Video Board. Preset Lighting Board. CrystalControlled Wireless Mikes with matching receivers.Subsonic Tone Control for audio tapes. 8MM SOFCameras and Projectors. Distribution Amplifierst Syn c. Video. Audio). Audio Control Boards(Studio ,i;, Remote) Proc-Amp with compensationand regeneration for adapting Helical Scan VTR'sto broadcast standards. PLUS specialized corre·sp o nde ncc courses in Telephone Engineering($39.50). and Integrated Circuit Engineering ($49.50). Plans from $5.lJS to $15. SUPER CATALOGplus years updatcing of new devices A ir MailedSl.()0. Do11 Britton Enterprises. PO Drawer G.Waikiki. Ha. %815. 4-73-121

FOR SALE: Random access unit for carouselGates RA-I. Used seven months. In perfect condition. $1200.00. W ACL, Waycross, Georgia. 8-73-2!

IMMEDIATE DELIVERY Revox 1302, Scully270-2, Sennheiser H04!4, Carousel 250-Rs,Carousel Selector. VJ F International. Box 1555,Min. View. Ca. 94040. (408) 739-9740. 8-73-lt

55



EQUIPMENT FOR SALE CONT

FIDELIPAC CARTRIDGES, Type A, used, assorted lengths. Over 700 in all. Open to offers,cash or equipment. Okanagan Broadcasters Ltd.,P.O. Box 100. Kelowna. B.C. Ph. 604-762-3331.

7-73-2t

CARTRIDGES-65 cents each. Used Fidelipacs invarious lengths and excellent condition. Minimumordcr-25. Send check or money order to Kartco,Box 291. Route #l. Stone Ridge, N.Y. 12484.Telephone (914) 687-9355. 7-73-3t

NEW AND USED TOWERS lSO ft. & I. 175 ft.Self Supporting Microwave Towers. 11 GHZ Antenna complete. 5 ft. X 8 ft. Reflector. AM FMand Communication Guyed Tower. Write DiSCO,P.O. Box 1029. Bradenton, Florida 33505 or call81J-745-6285 8-73-3t

HELP WANTED

CHIEF ENGINEER for like new non-directionali\M and automated FM. Southwest resort area.Full maintenance. Light air watch. Excellent working conditions. Medium-small market. LocalOwnership. 5800.00 per month start. Successfuloperation. Write Box: 284 Broadcast Engineering,1014 Wyandotte s., Kansas City. Mo. 64105.

6-73-3t

HELP WANTED CONT.

MOVE UP from your present job in broadcastengineering. We handle all engineering jobs andopenings coast to coast. Send full resume confidentially now. The AMPS Agency. 11661 SanVicente Blvd.. Los Angeles, Calif. 90049 8-73-tf

CHIEF ENGINEER - Announcer. W/First Ticket,for 2-tower directional daytimer. Modern CountryFormat. Excellent working conditions and facilities. Send resume. tape to: Irv Schwartz, WCLURadio, 1115 Ist Natl Bk Bldg, Cincinnati, Ohio45202 8-73-1t

PURDUE UNIVERSITY has an immediate position for an engineer to assume responsibility forclosed circuit TV facility. Must have experiencewith color cameras, VTR. system design andmaintenance. FCC first phone required sendresume and salary requirements to: Bruce Bahlke,Life Science Bldg.. Purdue University. WestLafayette, Indiana 47907. An Equal OpportunityEmplayer. 8-73-It

WELL QUALIFIED TECHNICIAN needed foroperation and maintenance of Ampex I200B,Ampex 3000 and Norelco LDH cameras. Sendresumes to Varicom, lnc., 485 West Milwaukee,Detroit. Michigan 48202. 8-73-2t

Growth Opportunities in TV& Radio Broadcast Equipment!

We are a leading producer of TV andRadio broadcast equipment with thefollowing openings in our Quincy, Illinoisoffice:

TV BROADCAST SALES ENGINEERS-QuincyOurTV SalesDepartmentis seekingwell trainedand experiencedsalesengineersto handleproductapplicationengineeringand preparationof bids and proposals.Experiencein TV stationoperations,TV marketing,transmitterand antennainstallations,and systemsplanning,is essential.

TV & RADIO BROADCAST FIELDENGINEERS-Quincy

OurServiceDepartmentis seekingwell trainedand experiencedTV and RadioField Engineers.TVserviceexperienceshould be in transmitters,antennas.or studio equipment.Extensivetravel isrequired. expensespaid. Radio serviceshould be in automationsystemsor highpower,highfrequencytransmitters.

ASSISTANT MANAGERBroadcast Engineering ExperiencedFor Our NYC Merchandising Center

Yourresponsibilitieswill includebroadcastequipmentsalesand retail operations.Formaltechnicaltraining is desired.Experiencein station operationsand engineeringrequired. Salesexperiencehelpful.Salariescommensuratewith experience,full companybenefits. including hospitalization,lifeinsurance.profit sharing, plus µaid relocation expenses.Send resume and salary history inconfidence(indicate positiondesired) to: TOM BEDFORD,EmploymentSupervisoror CALL (217)222 8200.

GATES DIVISION

HARRIS-INTERTYPE CORPORATION

Au Eouut Opportuuity Employer M/F

123 HAMPSHIRESTREET•QUINCY,ILLINOIS62301 U.S.A.

NEEDED IMMEDIATELY: Systems and Operating Technicians for Chicago with an independentproduction house. Experience in maintaining andoperating AVR-1"s. VR3000's, 1200-B's and C's,HS-200. color cameras. switchers and all associatedequipment. Salary commensurate with experience.Resumes should be sent to the operations manager,Edite) Productions Inc .. 1920 N. Lincoln Avenue,Chicago. Illinois 60614. 8-73-lt

56

SITUATIONS WANTED

WELL-TRAINED TECHNICIAN has 11 yearsexperience in electronics; latter 8 in network TVbroadcasting. Seeks desirable position in midAtlantic area. Particulars available. Write to Box286. Broadcast Engineering. 1014 Wyandotte,Kansas City, Mo. 64105 8-73-lt

advertisers·íloo~~mAmerican Data Corp. . 1

Belar ElectronicsLaboratory, Inc. . Cover 2

Robert Bosch Corporation 22-23Boston Insulated Wire &

Cable Co. . 8Broadcast Electronics, Inc .. 12, 51, 54

Cambridge Thermionic Corp 54Chu Associates, Inc. . 54Cleveland Institute of

Electronics .. .. 45Colorado Video 39

Danscoll 46Delta Electronics 44Ditch Witch Trenchers CE-2Dynair Electronics, Inc 47

Electro-Voice, Inc. . 9Ralph E. Evans Associates 54

Gates Radio Co. Div.Harris lntertype Corp 11, 27, 56

Grass Valley Group, Inc 3

Clifford B. Hannay & Son, Inc 50

International Tapetronics Corp 15

Vir James ConsultingRadio Engineers 54

Jensen Tools & Alloys _....•... 54

McBee Laboratories 17McMartin Industries, Inc 43, 54Mincom Div., 3M Co CE-7Minneapolis Magnetics, Inc. . 50Mosely Associates, Inc 43Mountain West Alarm Supply Co 51

Nasco Television Systems CE-8

Pacific Recorders &Engineering Corp. . 49

Polyline Corp _ 54

Oualitape Inc _ _ 48

Ramko ResearchRapid-O

.......... 52......... 53

SC Electronics Cover 3Sesco, Inc 54Shure Brothers, Inc Cover 4Spindler&Sauppe 16Spotmaster 12, 51, 54Smith & Powstenko 54Superior Continental Corp. . CE-5Switchcraft, Inc 48

Taber Manufacturing &Engineering Co 33

Technology, Inc 33Television Microtime, Inc 5

Ultra Audio Products ........•.... 17United Recording.

Electronics, ¡;re'. . ...•.......... 1O

"Vista Systems, Pnc .Vital Industries, Inc.

. . . . . . . . . . . . . . 46.. 7

Wilkinson Electronics, Inc. . ... 28, 53




Can ThreeAttractive SinglesShare A Unit WithNo Cross Talk?

If they are attractive 6-inch monochrome monitors from Setchell Carlsonthey can!

These uniquely designed monitorsgive you three, 16 sq. inch screens,while occupying only 7 inches of vertical rack panel space. Yet there is nocrosstalk between adjacent units due toeffective inter-compartment shielding.

Professional qualityand Americanmade, the moni-tors have a horizontal resolutionof 600 lines ...plus 100°/o solidstate circuitry,

and the most advanced single modulecircuit board currently available.

This unique SINGLE MODULE is aone-piece, easily removable chassiswhich permits rapid, on-the-spot maintenance for reduced maintenance costsand the elimination of valuable downtime. ALL components are readilyaccessible for ease of maintenance andtesting.

For broadcast preview, security andsurveillance, education,industry, medic a I monitoring,VTR and data display ... the SetchellCarlson Single &Triple-6 monochrome monitors... are the finestyou can buy.

Single-6also available.

SC ELECTRONICS, INC.A SUBSIDIARY OF AUDIOTRONICS CORPORATION

530 5th AVE. N.W. ST. PAUL, MINNESOTA 55112PHONE (612) 633·3131




modular roend control center 3.*Coordinate 1ound reinforcement a live TVfor 1455.40

Problem: An in-studio musical event with input signals from various sources - andyou have to make sure that the combined output meets both the special requirements of the housesound reinforcement systemand a live TV station feed. Soundstough, but Shure cuts it down to size with a pair of M6'7Mixers, stacked with ournew M610Feedback Controller. The M67's provide up to eight microphone inputs,each individually balanced, adjusted for signal llevel,a111dready to run "flat" into thebroadcast line. The combiinedoutput also runs fintothe M610Feedback Controllerbefore it reaches the PA system, where the M610's eight slide-switch filters plushigh and low frequency roll-off controls provide the house system with a "roomtailored" signal, shaped for optimum feedback control and maximumsystem gain!Result: good sound in the room ... and on the air.• More to come .. , other ingenioos sound control centers will be discussed in future 'issues.

Shure Brothers Inc.222HartreyAve., Evanston,Ill. 60204In Canada, A. C. Simmonds & Sons Ltd. H ®

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August, 1973/75cents BR08DC----- · PDF fileAugust, 1973/75cents ... down, an Indianapolis...

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