IFROMTHEMAKERSOFTHEFAMOUSGALAXYTRANSCEIVERSTheGalaxyFM-210 2MeterFM Transceiver Nowevery Amateur can buy Gal axy' s well-known qualityandperformancein a FM Transceiver! Thi s American-made ,soli d-state,FETfronte ndtransceiver offers no compromiseperform-ance fordirect or repeatercommunicati ons ... a full 5wattsof Power(or 10wattswiththe optional AC-DCPower Booster! ) Checkthe sespecs and you'll agree it's a lot of Transceiver for onl y $199.95!Seeone ... tryone!___--------- SPECIFICATIONS ---- ,Frequency range: 143-149MHz.AntennaImpedance : 50 OhmsNominalPower Req'mts: 12-14 VDC (or optional power booster)Transmitter: Power Input: 5 watts (10 W. with pow. booste r) Freq. Con-trol: 3Chan. crystal controlled Microphone: Hi ghImpedancereq'd. Deviati on: Adj' . narroworwidebandwithcl ipper filteralso adj. for optimum cippi ng level.Receiver: Sensitivity: SINAD.5uv forI2db, luv provi des 20 db quieting. Adj ustable squelch Modul ati on Acceptance: FMwideband(narrow band available) Type: Dual Conversion, FET front endfor minimumcross modul ati onandoverload IFFrequenci es:1O.7MHz and455 KHz Freq. Control : 3 chan. crystal controlled Audi o Output: 3 watts (intr' nl 3.2 spkr. )PowerBooster: Provideshighpoweroperationfromeither12-14VDC or117 VAC. Makes an ideal fixed station accessory. ($39.95). galaxy electronics " Pacesetter i n Amateur/Commerciai EquipmentDesign"10 South34th Street Dept. 7JFF46CouncilBluffs, Iowa 51501MAGAZINEP E TER BOROUG H, NEW HAMP SHIRE 0 345 873Magazine #109, October1969ContentsFeatures2 de W2NSDI111 Sold e ri ngAid19 TrV This One3 1 Autobandwidth39 :Mob ileHeater Switching49 :Shield ed Sreid75 Simp le Code()s(:i llalor111 New Produets113 PJ"opagat ion114 CrosswOI"d Punle122 BuV0. Rent128 Zl to SM Moonbounce128 NewAmateurTVRecord inVKI128 New1296mhzVKRecord131 ErrOl!iI134 l etters14 1 Caveat Empt or144 IndextoAdvert isersSTAFFEdit orsWayneGreenW2NS0l1KaylaBloakW1EMVAdverti singDiane ShawProduct ionRoger BlockPhil Pr iceNellie Si ldarJeff BarsantiJaneTraceyWhitneyTobi asAnBill MorelloMikeBalunCirculat ionLinGreenDorothyGibsonCarol RingComptroll erJoe La VignePro pagationJohnNelsonWTWEditorDave Mann K2AGZBooksWalter ManekMar k Kearney8 A Super -GainAnte nna for40Meters W4NVKNine db on40meters mightbecall ed"super ."12 OXCorner _.. . .. . . . . . . . . . . . . . . . _. K2AGZWTW report s and ot her OX jazz.20 FET Chirper . .. .. .. ... . . . . . . . . . ..... . . . . . . . . _. _ K6QK LS ignal sourcefo r peaking convert ers for optimum signa l/notse.24 TheInsideInfoon Alexa nder Graham .. . .... . , W2FEZOr- how thetelephonereall y works.28 LeakyLines .. . .. .. .. . .... . ........ . .. . . .. . .... K2AGZSimi larto"Grumb les:' but by alicensed amateur,no t a CB'er32 ScopeCalibrator _. . . . . . . . . . ... . . .. .._..Wl0lPGadget youcanbuild toimproveyour scope.34 Vidiou ThatHaveKnown Me K1YSOSense of humortest. If youfl unk. gobackto11meters.40 TheProtector ... .. ... ... . . . . . ... .. .... .. .. . . . . WACl HKCProtects yourgear from suddenline vo ltagesurges andinterr upti ons.42 Slower Tuni ng Rat es f orOlderReceivers . .. .. .. . . . . _. W4RNLJ ust li keband spread. '46 Posit iveIdent ificat ion ofCali bratorHarmonics K5 l LlKeeps youoff 6950 and o ther poor OXbands.50 Adapting AM Transmitters toFM. . .... ... ... . . . . . WA4UZMGoodHea vens.is everyone goi ng onVHFFM?52 CB Sets on Six .. .. .. ... .. ... .. . . ... . . . . . .. .. . WB2 FHWNoneed t ojunk thatCB rig whenyou ge tyo ur Tech t icket .54 Proporti onal Co ntrolCryst al Oven . . . .. .... . . . . . . . .W2CllYouneed this sort oft hing for moonbounceworkand such.58 A Crystal Filt erPhasing Control . ... .... .. . . . . . . .... ..W2l Tlook at theif responseinFig. 10 and be amazed.62 GroundedGridFilament Chokes . . .. . .... . . . . . . . . . . .. W21KYo u needthesefor linear amp lifiers.64 Equi pmentCabinets with St yle W20LPMakeit loo k commerc ial.66 VHFFM: Part I ..~ . . . . .. . . . . . . . . . ... .... WB2A EBAdvantages and practi ces. When are you go ing onFM?68 BringBackthe QMultiplier ... . .. . . . . . . . . . . . . . W8RHRInval uable forCW,no tches outAMcarriers. etc.70 Activati oninVP2 . . . . . . . . . . .. . . . . . . . . . .. .. . . . . VP2ACAngui llaIsland activated.73 The CRBeam . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . WA4FOQTwometer corner ref lector beam.76 TheARRL BoardandAma teurRadio . . . . .. . . .. . .. .. W7ZCAn ex ARRLDirector eva luates t helatestboard meeting.83 A Cheap andEasyPower Supply . . . . . . . . . . . . _. K4 FQUFor a sidebandtran sceiver .86 ExtraClass licenseCourse, Part IX StaffModulation. We'lI havelots ofargu ments onthis one.108 HamJa mboree . . . . . . .... .. ... .. .. . . . WB61ZFScouts h itt he hambands every October.116 OperationCat's Paw . .. . . . . . . . . ..... . . . .. W1ZCWhi msy.123 Knight V-l07VFO forSi x andTwoMeters K6GKXTest reportby ahappy user .124 CareersintheFAA W6J TTGet onthe governmentpayroll.132 Yout hForum . .. . . . . .._ . .. . WA1GEKTeenagers. arise!7 3 Magazine is published by 7 3 Jnc ., Peterb oro ugh. N. H.03458. Subscript ionr ate : $12.00for thre ey ears, $6.00 fo r one year . Second Class Po sta ljte paid a t Pet erborough , New Hamp s h ire , an d a taddit ional maili ng o ffices. Print ed a t Pontia c, Iutnots. U.S. A. Ent ire co n tents copyr igh t 19 69 b y 73Inc ., Pe t erbor o u gh , NewHamp shire 03458. Ad dress labelcyp her: yourcallle ttersshou ldf ollowy ourname . If we' ve had to make upa call just dro p u s a n ote a ndwe' ll changeit toyour r ea l call . T henumber under the call is o ur cod e for the last issue o n your s u bscri p ti o n . T hefirst n u mb er is themon t h , theseco n d they earof thelast issue. 50 wouldindicate expirationwithMay. 1 9 70. Renewaln o ti cesare preparedaheado f time an d youmayr eceive o neor twoafter yours ub s cri p ti o n has beenr en e we d . Viewthis si t u a t i o n withhumor andtolerance. Tell your friends ab o u t it. if youmust, butd on'tfeel it necessarytotell u s. Wea lr ea d yknow all toowell about it.OCTOBER1969 1GravityWavesSolution toVietnam?Making ExtraMoneyMaking $1,000,0001ReactionariesMarathonNets 'FCCActions... de W2NSD/lWayneGreenGravity WavesMythankstooldfriendNeil W20LU forsending in a clipping fromthe NewYorkTimes announcing that ProfessorWeberofthe University of Maryland has detectedgravitation waves. Theexistenceofgravita-tional radiation is predicted by Einstein'sGeneral Theoryof RelativityandProfessorWeber believes that he has experimentallyverifiedEinstein's prediction.Acentury ago Maxwell predicted frommathematical calculations that there wereother types of electro-magnetic radiationthan light rays. In 1888 Hertz confirmedMaxwell'spredictions andopenedthe radiospectrum.AsI mentioneda fewmonths ago, here isa field that is wide openfor the amateur.Thereare no professionals in the fieldyet.What, allofuswant toknow, is the velocityof propagationof agravitywave?Speedoflight? Instantaneous? If it isfaster thenitwould make a wonderful communicationmediumfor interstellar contacts ...andmight explain howthose pesky UFO's areable toget herefromplanetarysystems sofar away that reputable scientists say thatthey cannot exist just because there is nopossible wayfor themtocome that distance.If you have any info to pass alongongravitygenerators or detectors, let's pass italongthrough73.Vietnam Solution?The educated opinion seems tobe thatPresident Nixon has been hoping that hecouldusethe same route for settling the warthat Eisenhower used for closing out theKorean conflict. That meant workingthrough Moscow, who, becauseof theChi-nese difficulties, were supposed to beanxious to accomodate theU.S.This approach doesn't seem to haveworked out in practice at all, a situation2which leaves us still boiling in our ownkettleof soup. Unilateral disengagement means,essentially, theslaughter of most of SouthVietnam, thehistoric consequence of losinga warinAsia. This, inturn, canhardly helpthenon-communist forces in Laos, Thailand,Cambodia, Malaysia, BurmaandIndia. Anypromises we have made inthepast of helpwill hardlybe honored after thedisaster inVietnam, and theyknow this.Obviously, getting out of Vietnam unilat-erallyis a very bad solution to our problems.Should we then turn around and escalateagain?We have seen that the communists areable to match every escalation. They havenointention whatever of losingthe war. Theyhave beenatit formany years there and arenot about to drop it now.Thisis a subject that can better be arguedinabook-lengthformthanabriefeditorialcomment such asthis, howeverI would liketomake anabbreviated suggestion for a newcourse of action that might possibly provemore rewarding. I wroteabout this a coupleyears ago upon my return fromAsia, but notmuchcame of it. Theideasstillseemquitevalid ...perhaps evenmorevalidthan ever,since more options have beentriedinthemeanwhile withoutnoticeable success.Basically, I propose that the Pentagonand the State Departments do not have acornerontheU.S. brain market. Experiencehas rather indicated negatively in this re-spect. Possibly then, we could do better thandepend upon themfor our total effort inVietnam, directing the fighting and peacetalks, which about sums up our activitiesthere.Just suppose that we decided to fight amuch more basic fight, using our biggestweapon? The bomb? No, not at all. Thebattlebetween communism and capitalism is73 MAGAZINEor experimenter!International EX Crystal &EXKitsOSCILLATOR/ RFMIXER/ RFAMPLIFIER/ POWERAMPLIFIEROXOSCILLATORWri t ef or completecat alog.SAX' Transistor RFAmplifier $3.50Asmal l signal amplifier todriveMXX-1 mixer.Si ngletunedinput andl inkout put.LaKit 3to20 MHzHi Kit20 to170 MHz(Spec ifywhenordering)PAX-1 Transistor RFPower Amplifier $3.75A single tuned out put ampl ifier desi gned tofollowtheOX oscil lator.Out putsupt o200mwcanbe obtained depending onthe frequencyandvoltage. Amplifiercanbeamplitudemodu-latedf orlowpowercommunicat ion. Frequencyrange3,000to30,000KHz.BAX-1 Broadband Amplifier $3.75General purposeunit whi chmaybeusedasatuned or untuned ampli fier in RF and audioapplicat ions 20 Hz to 150 MHz. Provides 6to30dbgain. Ideal for SWL, Experimenter orAmateur.SAX-,Crystal controlledtransistorty pe.LoKi t 3,000to19,999KHz $ 295Hi Kit 20,000to 60,000KHz(Speci fywhenordering)MXX,MXXl Transistor RFMixer $3.50Asingletunedci rcu it intendedfor signal con-versioninthe3to170MHzrange. Harmonicsof the OXosc ill ator are used for injection inthe60to170 MHzrange.LaKit 3to20MHzHiKit 20 t o170 MHz(Speci fywhenordering)PAX-' BAX'CRYSTALMFG. CO. INC.10 NO . LEE OKLA, CI TY. OKLA. 7310 2OCTOBER 19693most fundamental. Whynot use capitalismas aweapon? This isone weaponthat hasbeenalmost irrestibleso far and yetwe havemade little effort to use it.For afractionofthe $100millionadaywe arespendinginVietnamwe couldshipproduction machinery fromthe U.S. tosetup factories around Vietnam. I envisionachange fromthepresent agriculturalsystemtoahalf agricultural, halfindustrialsystem,with factories spread out so that workers cancontinuetofarm part time. ]wonder if thisisn't a happier way of living than ourall-or-not hing arrangement?Factories in undeveloped countries arerather basic affairs and far less expensivethanthoseinourcountry. Witharelativelysmall investment we couldspreadfactoriesall overVietnam, providing jobs part time inhundredsof villages. Would the people makethe change? If theincent iveis there, theywill. The incentive that I haveseenchangeone country after another into industrialcountries has been the availabilityof inex-pensive cars and televisionsets. Peoplewillwork incredibly hardfor these pleasures.Suppose weset upa fewdozenfactoriesmaking prefabhutsandbasicfurnitureandgave these products to the Vietnamese, alongwitha small plot oflandfor agarden?Notonly would we be able to clean up themiserable camps nowhousingthousands ofrefugees, but wewouldalsohavesomething,veryinterestingto offerdefectors fromt heNorth. Cars, TV, and other luxuries wouldhave to beearned.The whole bill for agive-away programlikethai might cometo$1000 per defector,but that is asmall fraction ofwhat wearepaying right now to try andkill them as theycome down to fight. It iscostingus some500 times thatmuch!Oncewe convertVietnam to a capitalisticsystem, they will be forever broken awayfrom the old patterns and can soon taketheirplace among those Asian countries whohave made the change ... Singapore ...Thailand ... Japan. There are plenty ofmarkets inAsiafor productsmanufacturedin Vietnam since few of the neighboringcountries are developed.Does that sound betterthanthealterna-4tives of fight harder or quit?DangerAsthose of youwhoknowme personallyknow, ] love to eat and as a result Iamgenerally a bit on the heavy side. Everycouple ofyearsorso] go on a diet and takeoff the accumulated layer. This summer,egged on by the wonders of the Doctor'sDiet, a lovely invention wherein you catmeat and drink water. . .and not much else, ]decided to maketheplunge. Thebooksaidthat Icouldalsodrinkallofthediet soda Iwanted alongwiththe diet, soIloadedupon my favorite flavors of "tonic,"astheycall it up here in NewHampshire, all sugarfree.Fat free beef andfat freechickenleft mewith plenty of hunger pangs, but the dietsodafilleduptheemptyspacesandI foundthat I was drinking more and more each day,getting up tosome four bottles aday. Noharm done, so whynot?Alongabout thethirddayI began to findit difficult to focus my eyes and I startedhavingperiodsof vertigo. This got progress-ively worse and by the seventh day Icouldn't even.see to type, muchless readmanuscri pts andproof-read articles. My eyesjust couldn'tfocus anymore at all. I realizedthat meat certainlywouldn't dothistome,and sincetheonlyotherthingIwaseatingwasdiet soda, it obviouslyhadtobethat. Istopped.Within a couple of days the headachesstopped, the vertigo stopped and my eye-sight beganto improve. After a week I couldread medium-sized print again and type.Thesecret wasrightthereoneachbottle,ifIhadtakenthe timeto read the fineprintwhilemyeyeswerestill working. That stuffis supposedtobeonlyfor peoplewhohavebeenrequestedbya doctor torestrict theirintakeof sugar. .. diabetics. InmoderationI suppose it would not cause noticeabledifficulty. Whowouldnotice his eyes slowlydeteriorating over a period of weeks ormonths and tie it inwithdiet soda? Evenoccasional headaches andvertigomight notbe suspected. And who knows what otherdamagethesebeveragesmay bedoing? Theycertainly must be able to have a profoundeffect on thehumanbodytobeableto dome in so quickly on such a small dose.73 MAGAZINEWorld'sLargestElectronic Kit CatalogNew1970 Edition ... Over 300 Kits ForEvery Interest. Save Up To 50%Learn how you can build sophisticated el ectronics at 50%savi ngs ... nospecial skillsneed ed. famousHeathkitinstruc-t ionsshowyouhow, f reet ec hnical consultationavaila ble ...enjoy t hefunandsatisfactiono f b ui ldi ngthebest ... Delu.. Color TV . .. The . eUyo u've heard a nd r. adabout thatgive better performance vet conno more ; ,i.model . : 295. 227. &.180 I C! . in . rectangul ar ; with orwithout AFT ; all with exclusivebuilt -in self-se rvicing aids f or bestpictures a lways; c usto m. wall o rcabi ne t insta lletion ; opt ional wire -le ss remot e cont rols. Als o newHeethkit antennas. t o wers. and de -luxe1Z" B lit Wportable TV.e Stereo/HI-FI Components ...Transistor stereo rece ivers (inc lud-ing the w orld famous HeathkitAR-1S). amplifiers .tuners. speak -ers . turnUbhts . cart ri d ges. f ur-nit u re.e Transistor Organs . .. Oeluxe19- vo ice "P..a moun t " a nd lowcost 10-voice Tho me s modal s inkit formw ithinstant -play Col or-Glo" keys- saveupt o.500. Als oPercussion e nd Rhythmacc esso-ri es.8 Music Instrument Amplifi ers .. 20. 25 lit 120 wett amplifiersfor le.d a nd bass i n. trume nts : dis-t ort io n booster hll8dphone .mps.plus mikes a ndsunds .e Home Equipment . .. Intercom.tableradios . garaged ooro pene rs.portsbler.diosandphonographs.homeprotect ion syst ems .8 Shor'tW.ve Redios . .. Mu lti _bend s ho rt weve receivers. solid-stete.ndtube-tyP'0'''-c-'0'. ;j- 0000" , ' ,-, , MOOUI.ATORIISPOT1."' - '-,.,.BMi"lzFig. 1. Circuit d iagramof theconverter transmitterus ingthe8 mhz osci llator-triplerand thedoubter stage. Coils L 1, L3. L4were a lready in theset. L 2wasobtai nedfroma noldTVchassis. This circuit diagrammayseema b it incomplete. b ut sinceeveryCBset is differentt hec irc u it must beb road e no ughtocover a ll models. Asa resul t. some exper imentat ionw il ibe necessary to determine thep roper coils tobeused .transmitter conversion is now complete.Tune UpProcedure: I. Hook a No. 47pilot lampon the antenna jack or terminals.2. Set each coil for the approximatefrequency indicatedonthecircuit diagram.3. Makesuretheoscillator isfunctioningproperly. This can be determined by lis-teningtothesignal inanearbyreceiver. Ifthere is aspot switchontheset it can beused to list en to the oscillator in thetransceiver's receiver.4. Put the rf probe of the vtvmonthegridof the doubler stage, and tune Ll formaximum rf indicationonthemeter (maxi-mumpointer deflection). If anrf probe isnot available, put oneendof a I N34or anequivalent diodeonthe end of the vtvm's deprobe, and touch thefreeendofthediodet o the circuittobemeasured.5. Place therf probe on the gridof thefinal, and tune L2 for maximumrfindica-tion.6. Place the loading capacitor at mini-mumcapacitance, andtunetheplate tuningcapacitor for maximumbrilliance of the No.47 pilot lamp previously hooked up. In-crease the loading byincreasingthecapac-itanceoftheloading capacitor,andthendipthecurrent usingt heplatetuning capacitor.7. If an overtone crystal is used instead ofthe8 mhz oscillator-tripier, thetransmittershouldbetunedbyresonating the oscillatorplatecoil to50mhz. Therest ofthe tuningis done as described above.You now have a complete lowpowerstationforsixmeters. All that remains to bedone is to hook up the antenna anda mike. Imight add that there is really no need tohave to switch the beamfromt he bigsixmeterrig, t ha t is if you have one; the set gotout quite well ona simpledipolemountedon a stick of board. The total cost ofconverting the rig was nothing, as all thenecessaryextra parts were available from t heshack junk box. Soif you want to have somefun on the band which is becoming morepopular every day, t ry this simple con-version; you' ll be glad you did!. . . WB2FHW &WA2HNJoscillotortrnonitor 11'1 udi"l.hMl. holI'Io..ihorth. RF oJ . ")1 cwtr....", itt.rfro",10M.hoIk. (,100kc to1000Me.u.i.., Otlly ... a",.ic...., . ..t.n.... unIN IJ-tritt.reel lor cod.pr.me. 01' Ul. keti..,oJ ..lid.t.tt. compo...nts .nd circ.. its . .id. in tun;", .. , (, t .d;.. , RF..a ll"or .r.4 power eire.. its. ,. tr.n.idor, 2diodecirc.. it,.""'."." ton dj...t,. AA ,enc.n,-" Id., a' .nt., {" ",. , nwc...... . 1495c_ , leh, i. 16 '.Ut. "'U"{" cl ., ppd....a&c.n......i..d . I..min.. m, 3." _ 2.3_ 1.2" . e nd a d '-ck Ot' m.e.US -.I. (,t ...,.nwMfwI)lM r .bymall onl yJa mes Research compa ny,dep't: A R-M20 WillitsRoad , GlenCove, NY11542V -IBR0 P LEXENJOYEASY,RESTFUL KEYING520.95t o543.95THE VIIROPLEXCO. , INC.833 Broadway,N .Y. , N .Y. 10003OCTOBER 196953!Proportional ControlCrystal OvenRobert S. Larkin, W2CLLRFD1 Box 28RFlanders, New Jersey 07836... c. FEE DBACKFig. 1. Simplifieddiagramofoven tempera-ture control.DC- - ----OETECTOR,,.... ----all offandall onandstays there. If there isa change in the temperature outside the oven,theheaterpowerwill readjust automaticallyto keep theoven temperature constant. Thistypeof ovenis usedinalmost all precisionfrequency standards in commercial use today.Manyideas usedin the designof thisovencame from an article by W.L. Smithl.Aninterestingaspect tothis type of ovenisitsrelatively lowcost. Withanykindofjunk box at all, this proportional oven can bebuilt for lessthanthecost of a thermostatictype crystal oven., II '_ IT HR Ill \S ,QRI HEATER II II I: OVEN IL ...1When theultimateinstabilityis requiredin an oscillator, a temperature controlled ovenmust be used. Until recently, ovens took theformof aboxsurroundedbyaheatingele-ment and containing a thermostat. When thetemperature is too low the thermostat closes,causing the heating element to come on. Af-ter the temperature rises to thethermostatswitching temperature the heater goes off, al-lowing theboxtocooldown. Thisprocesscontinues with a full cycleusuallytakingafew seconds. One limitation of this system ishaving the heater either on or off Thismeansthat at all times there is either too lit-tleortoomuchheat beingapplied. The re-sult is acyclingof the box temperatureastheheater goes on and off.Inthe course of someuhf communica-tions experiments,wherea stablefrequencyand time reference were required, the oven des-cribedhere was built. This oven is capable ofmuch better temperature control than the oldthermostatic type of oven. Proportional con-trol is used toallowthecorrect amount ofheat tobe applied. Once the temperature ofthe oven reaches thecorrect temperature, theheater poweradjuststosomelevel betweenVector board is used for the electronics.The 2 watt heater resistors can be seenclamped around the Minibox oven. Whenused, the oveniscoveredbyinsulatingma-terial.54 73 MAGAZINEJULY 20, 1969Astronauts beam "live"TVpictures direct from moonto mrth!!Join the SPACE-AGE"Jet-set.. .bu ild II Solid-Stnr: 'FV Csun orn:If you'relooking for aNEWchallenge, we offer you pioneering in home telecasting.EventhoughYOU can't go to TRANQUILITYBASE...YOUCAN TELEVISEYOUROWN "Live" TV!! The onlyknown solid-state camera kit availablein USA. Completely self-contained including powersupply. High performance. straightforwardcircuitry. Over four years of laband field testing.SPEOAl FACTORY -DI RECT PRICE AVAILABlE TO CUSTQl.\ERS O;: DERINGDIRECT FI/(),\ THIS ADORWITHIN T\I(l wEEKS AFTER RECEI VINGOJR C(lVCATALOG. REGJl ARPRICE: $1 29.950 V1D1CCNneeMlT INQ.UDED. AVAILABlE SEPARATELYFOR $36.MoDn XNA, SERIESC-2 SPECIFICATIONSPOrER REWIREIoENTS: 12l)..a,PHONE fOR fASnST SElMCE1 DIAl. 402-987-3771DAKOTA CITY, NEBR. 6B731, ,L ...JCir cuit is formed so when the resistanceofthethermist orisequal t othat of resistorR,novoltageisfed backt othe inputof theacamplifier. When the thermistor is cooled, it sresistanceincreases. By choosingthe correctphasing of the transformer windings this will6 00 CT, knownasW2EWL sset r ansfo r m er .,;:];"0causepositivefeedba ck around the ac ampli.,0'00- , ."+ 12V 3AWP WA)(TEMPSE Tro. '" I I E 600'000JC.T.33'" !l200r'0'+CT .,ri.r/" IN29!l

2: HI6T'"..,..:;+L!l V.cr." 0]'00 / 2J'o14 04" 00" 00 IH29 !l " 02 N404l l .// hr r 2NI 14CAPACITANCE I NUFD ......- - -- -F ig. 2 . Diagram of p ropor tion al ovenc ontrolas descr i bedint ext., ,,HEATER,R 1 T her m i st o r , lOOOf! at 2SoC,G E 20102., ,, 161l !l OHW ,avail ab lefromNewar k E l ec. .5 0 0N . Pulask i , 2WATT ,Rd.,Ch icagoIL, part no .3 0 F 1 13 1, $ 1,60, ,S20 0CT : 22 ,OOOCT:, ,T1 A u d io Tr ansfor m er - , ,CircuitOperationof theovencont rolisbest un-derstood fromthe simplifieddi agram. Thether mistor is a temperature sensitive re-sist or2. Mechanically, it is at tachedt otheinside of the ovencase. Elect rically, a bridgeOCTOSE R 196955Thethermistor canbeseenmou ntedon theinsideof the Minibox oven. Paint was re-movedfromthebox wheretheresistors aremounted. Anunpaintedboxwouldbe pre-ferable.fier creatinganaudio oscillator. The voltagelevel fromtheoscillatoris converted to a devoltagebythedetector. A deamplifierrai-ses thepowerlevel toa maximumof about25 watts todrive the ovenheater. Astheheater warms the ovenand the thermistor,thebridgeis brought back to balance by thelowering ofthethermistorresistance. If thethermistorresistance is lower than that of R,negative feedback occurs around the ac ampli-fier andno oscillation will exist. In this way,poweris applied to the heater only when thetemperature oftheovencase is less than thedesired temperature.Between thepoint of no oscillation of theac amplifier and fullclipped oscillation, thereis some voltage level that allows the heater tosupplyexactlytheheat lost fromtheoven.Rather amazingly, this feedback arrangementwill eventually find this balance point andbringthe heater power toaconstant level.Typically, this takes about 30 minutes.The actual circuit uses two 2NI67transis-tors in the ac amplifier, and two2N404'sanda2Nl74inthe de amplifier. These par-ticular transistor types were used becausethey were readily available. Almost any simi-lar type should perform satisfactorily.Withthe componentsshown, oscillationoccurs atabout800 hz. A fullwave detectorprovidesamaximumofabout 8 volts to thedeamplifier. Thisamplifier uses three emit-ter followers for unityvoltagegain, withacurrent gainofabout 20,000. The heater isbuilt fromsixISohm,2watt carbonresis-tors in parallel.ConstructionThelayout isnot at all critical. Aheat56sinkof about 8squareinchesareawasusedon the2N174.Astandard 2-3/4"x2-1 /8"xl-5/8" Mini-box(BudCU 3000A) forms thewalls of theoven. AISohm2wattresistorisfastenedby a cable clamp on each of the six sides. Toprovide good thermal contact , the sideofeachresistorisfiledflat to a width of about1/8". Transistor heat sink thermal compoundis appliedbetweentheresistor and the Mini-box. All sixresistors are wired inparallel toformthe heater.In order to minimize the time requiredforthe thermistor tosensetheheater tempera-ture, the thermistor is mounted inside the boxbehind one of the resistors. This gives a ther-mal lag of about 30 seconds and allows a rea-sonable warm-up time for the oven. Thethermistor iscarefully solderedtoa groundlug that is thenelectricallyinsulatedfromthe side of the ovenby a mica washer. Again,heat sinkcompound is usedtoincreasethethermal conductivity.OperationThe only initial adjustment required is the0~~z INSIDE TEMPERATUREu>I , ,-~ . HEATERiVOLTAGE~z!!e,.TIME MINUTESFig. 3 . Ovenwarm-upcharacteristics. Tem-perature measurements were made lit thecenter of theoven.phasing of TL If oscillation does not occur,orif operationis veryerratic, the 600ohmwinding connections should be reversed.Normaloperationisindicatedby a warm-upcharacteristic similar to theone shown in thegraph.Theovenshouldbeenclosed in an insula-tedbox. This reduces both the heat loss andthe magnitude of harmful transient events73 MAGAZINENEW FROMHEAVY DUTY SSBPOWERTRIODETYPE 572B/T160L Ideally suited for grounded gridli near ampli fier service. Rugged graphiteanode. Compact Envelope, Durable bondedthori atedt ungsten f ilament. Relat ivelylow operating vol tageminimizespowersupply cost. Zerobias- nobulky auxi liarypower supplies. Maybeusedininst ant-on, no warmupampl if iers,forhomebrewl inears. Inmost instancesthe572B/T1 60L di rect ly repl aces the 81l Aprovidinggreaterpeak powercapabi lityandlongerlife.MA.XIMUMICASRATINGSPERTUBEDCplatevol tage 2750vol tsDCplatecurrent 275Ma .Platedissipat ion 160watt sFilament power 6:3V@4.0AmpsAMECODIVISION OF AEROTRON, INC.u. S. HIGHWAY1, NORTH. P.O. BOX6527 RALEIGH, N. C. 27608 RadioAmateurs'Prefiusby Countrin! A,R.R.L. Phonetic Alphbet! WhereToBu)'! Grut Circle BearinlS! International PostalInformationl PJus much more!GETYOURNEWISSUENOW!Over 283,000 QTHsin theU.S. edition$7.95Over 135.000 QTHsin the OX editi on$4.95your favorite deal er ororder dire ct (add25fo rma ili ng inU.S., Posses sions& Ca nada. Elsewh ere addSO ).RADIOAMATEUR 116 kl.tc a 00 INC.Dept. 8. 925 SherwoodDriveLake Bluff. III, 60044 QSL ManleenAroundtheWorld! Census of hdio Amateursthrour;l'Iout the world! RadioAmateurs' LicenseClan! WorldPrefitMap! I nternat ionalRadioAmateur Prefil"',,,' ..;..:===='- _ThesevaluableEXTRA featuresincludedin both edit ions!WI'''. w'ORfRttBROCHURE!...W2CLLsuchascoldbreezes. AI"to 2"layer offoamrubberorfiberglassis adequate insula-tion around the oven.The contents of theoven should not touchthewalls. Components insidetheoven arebest mountedbyathermal insulator such asfoam rubber.Byadjusting R, the temperatureintheovencan be set toalmost any temperature a-bove the ambient. Themaximumtempera-tureattainableis limited by the25 watts de-liverabletotheoven. If theoven is well in-sulatedfromtheair thiscanmeantempera-tures over 100' C sobecarefulor youmaymelt your new precision standard! Evenabove about 75' C somecomponents maydeteriorate. The oven takes about 30 minutesfor the insides to warm up to a constant tem-perature. Asshowninthe graph, the heaterpower steadiesupinabout 10 minutes afterhaving considerable overshoot.Bibliography:I. W. L. Smith, "Miniature Tramistorized Crystal-Controlled Precision Oscillators," IRE Transactionson Instrumentation. September 1960.2. C.K. Klinert, "The Thermistor," 73 Magazine,November 1968, p. 78.OCTOBER 1969 57Donald MeadW2LT235 SouthIrving StreetRidgewood, NJ 07450A Crystal FilterControl"They can make friends enemies, andenemiesfriends, byphilters,"TheAnatomyof Melancholy, Burton, 1621.Yes, even back in the 1600s, it seemsthey were usingfilters ... er, philters, thatis ...' toperformuseful featsofmagic. Andwhat betterlegerdemaincan be found in themodern communications receiver than acrystal philter .. . filter, Imean.Fig. 1. Frontviewof the unmodifiedcapa-citor.A crystal filter is useful in improvingreceiver selectivitybecause of its abilitytopass one frequency while attenuating allothers. It has another useful attribute aswell - its ability to null out a specificfrequency near the acceptance frequency.Theuse of a phasing control permits the nullfrequency to be varied slightly so that anear-byinterferingsignal can beeliminatedwithout unpeaking the desired signal.Althoughthecontroldescribedwasusedinthe "SecondChance"circuit," it canbeused injust about any standard ifcrystalfiltercircuit withuntunedgrid. The phasingcontrol, which issimplya three-plate vari-"A Second Chance Crystal Filter for theBC-348", 73, June, 1966.58able capacitor, is mounted and wired inplace of the rotary"crystal on-off' switchon the front panel of the BC-348. Theproblem is - try to find a small variable withaninsulatedrotor shaft inanyof thepartscatalogs! After much looking, we becameconvinced that the only way wecouldgetwhat we needed was to make one. Thevictimwas a small APCvariable capacitorwitha short slotted shaft and locknut. Thesehave beenadrugonthesurplusmarket foryears and can be found very cheap. Figs.I- 4 show details of the modification.Surgery is performed as follows:a. Remove anddiscard the locknut. Next,withaknife blade or slender screwdriver,spread the four slotted parts of the shaftbushing apart andbend them away fromtheshaft. Flex thembackand forthuntil theysnap off.b.Remove thecollarfromthetipof theshaft by filing a slot in the collar. It ismounted on the shaft witha force fit andcan easily be pushed off onceit has beenweakened by filing.c.Positiontheshaft so that the plates areFig. 2 . Sideviewof theunmodifiedcapa-citor.73 MAGAZINE""I ,"HIGH, ,,, PEOA'OC EFig. 5. The variation of impedance as afunctionof frequency .(B)Fig. 4 . Shaft details; (a) before modifica-tion, (b) after modification.coversthetwomachinescrew heads holdingthecapacitor inplace. A small piece of blackplastic tape may be placed on the back ofthe panel tocoverthesmall holewhichtheswitch anti-rotation lug occupied.Bybendingonecorner of the rotor plate,the capacitor will short-circuit itself whentheplatesarefullymeshed. This will disablethe crystal filter and provide normal low-selectivity reception.One wordofcautiononconnectingthephasing capacitor across the crystal - besureyouconnect thegridside of the crystaltothestator. Weinadvertentlyconnecteditthe other way first and heard a beat noteevery time we touched the metal knob. Itturned out that a local Bestation, onlyakhzawayfromthe if frequency, was gettinginto the if amplifier through the shaftinsulation capacitance, tiny as it is! Re-versing the connections cured this.To understand howthe filter is able toperform this dual role, a small dose oftheory may be helpful. First of all, it isimportant toaccept the fact that aquartzcrystal hastworesonant frequencies. Oneistheseries-resonant frequency. at which thecrystal offers almost zero impedance; theother, about I khz higher, is the parallel-resonant frequency. at whichthe impedanceis veryhigh. The variation of impedance as afunctionoffrequencyis shown in Fig. 5. Atthe series-resonant frequency. the crystalacts like a series-connected coil and capa-citor. L-Ccombinations like this areusefulas wave-traps toshort-circuit undesiredfre-disengaged. Thenwithdrawtherotorassem-bly, takingcarenot to bend the three-leggedflat shaft spring (one legis therotor con-nection terminal lug). File the rough surfacesof the shaft bushing on the front of thecapacitor until the bushing presents asmooth bearing surface. Removeall but thetwo stator plates and the one rotor platenearest the ceramic body of the capacitor bygently bending the plates back and forthuntil thesoldered joint fractures. File or clipoff the excess portion of the stator platesupport pins and the rotor shaft.Fig. 3. Side view of the modified c apac ito r.d. Prepare aninsulating sleeve that canbeforced over the rotor shaft to receive thetuning knob. The sleeve must be 1/4" indiameter and can be about I/Z" in length.We used a plastic test prod handle, cut tolength, that merely needed enlargement ofthe bore down the middle. ANo. ZI drillmakesaholethat fitssnuglyoverthemetalrotor shaft. The tight fit is importantbecausethesleeve mustbe forced on in sucha way that the rotor contact spring iscompressedandtheproper spacingbetweenthe plates is maintained. Incidentally, therotorspringmaybe flatteneda bit to relievesomeof thepressureit exerts. Itneedonlymake good electrical contact against theshaft shoulder whentheplatesareproperlyspaced. A small metal washer is usedbetweenthebearing end of theplastic sleeveand the filed surface of the bushing topreventabrasionof thesleeve. To assemble,place the rotor contact springinposition,insert therotorshaft through the spring andbushing, add the metal washer over theshaft, andforce the plastic sleeve over therotor shaft until the pia tes are properlyspaced, noting that the spring is slightlycompressed and makinggoodcontact withtherotorshaft. This completes the capacitormodification.Thephasingcapacitorismountedonthepanelinplaceofthe"crystal on-off" rotaryswitch. The original knob is re-used andOCTOBER 196959quencies in the output circuit of a trans-mitter orintheinput circuit of a receiver,for example. Onthe otherhand, thecrystalalsolooks likeaparallel-connectedcoil andcapacitor at aslightlyhigher frequency. Thecrystal in the grid circuit ofaconventionalcrystal oscillator stage makes use of thisconfiguration. Almost everyone is familiarwiththefact that thefrequency of a crystaloscillator can be lowered slightly byshunting a small trimmer capacitor acrossthe crystal ... a point to keep inmind.c,o.II01.... ...I0)1o.Fig. 6 . Theequivalent "blackbox"electri-cal circuit .How can the crystal do two things atonce? Let's take a look at Fig. 6 whichshows the equivalent"blackbox"electricalcircuit. It is clear that Cx and Lx arearranged in aseries circuit. However, Ch,representing Ibe capacitance of the holderand.wiring, is shunted across ex and Lx.definiteeffect onfrequency. If thevalueofChisincreasedslightly, the parallel-resonantfrequency of the crystal will be loweredslightly.Inthe conventional if bridge filter circuit,showninFig. 8, the phasing capacitor, Cp isadjustedtobalanceout theholdercapacityChso the crystal will passonlyfrequenciesat which it is series-resonant. Cp can bevariedslightlyeitherwayfromthe balancedcondition to indirectly affect the parallelresonant frequencyof the crystal. Anotherway of doingthis, especiallyintheBC-348receiver, is to connect a small variablecapacitor, Ca, directlyacross the crystal topermit smallincrements of theholdercapa-cityasshowninFig. 9. If trimmerCp is settobalanceout the holder capacity plus, let'ssay, half ofCa, thenanychangeinCawillcause Cpto have a surplus ordeficiencyofcapacity as far as balance is con-cerned- exactly the same effect as if Cpwas the variable control.o.oc.o. --,--4-1I"Fig. 7. The parallel resonant combination.Redrawing it, as showninFig. 7, reveals theparallel-resonant combination. Consideringthe series-resonant condition, the presenceof Ch has little effect on the resonantfrequency; all it does is to act as aninsignificant by-pass capacitor. However, inthe parallel-resonant mode, Ch exerts a.1. ,,;: "'-----4I,.Fig. 8 . Conventional bridge circuit with thephasing capacitor adjusted to balance outthe holder capacity.60.",.Fig. 9 . Asmall variable capacitor is con-nected direCtly acrossthecrystal topermitsmall increments of the holder capacity.Aword about if alignment isin order.The BC-348 selectivitycurvewiththefilterout isas wide asthe proverbial barndoor.To make things worse, theiftransformersare slightly overcoupled, making for adouble-humped response curve. Originally,we felt pangs of sympathyfor thedesignerwhohad toaccommodate boththebeaconbandand thehfbands, withtheresuIt thatthe if landed in the be band. But to. deliberately broaden the selectivity thatmuch! No doubt the military wanted areceiver that stoodachance of gettingthemessage through when tuned roughly toaspot frequency.The rough alignment can be made onbackground noise. With. thebfoonandthe73 MAGAZINEs

--!I'","-," . , , ., ."-, ,, ,'ll ' , , ,,,, ,, , ,:1 , ,, ,

, , ,I FRESPONSE,, ,,, ,CURVE,,,, ,,,,,,,:i,,,, ,, ,,,,,,\ ,, ,/,, ,, ,I!x T4L,,,,,OU',,XT4 Ll lIN,tionslot. Tryother offsets fromthe align-ment frequency; at least onesettingshouldresult in almost infinite rejection as thephasing control is tuned through it.When operating the receiver inthe "single-signal" mode, the phasing control is usu-ally set so audio images fall in the re-jection slot. That is, the bfo is set to adesired pitch that corresponds with thecrystal filter peak frequency. Then, thereceiver is tunedto the same pitchontheothersideof zerobeat. Thephasing controlisthenadjustedtoeliminatethissignal (theaudioimage). Inthis way, half thepotentialinterfering signals are automatically elimi-natedwheneverthe desired signal is tuned inon the crystal filter peak.Fig. 10. The beforeand after if responsecurves.90B 9 10 91" 91 4 916 91B 9 z0 9 aaFREQ ,,,'0a,-,

-Theproof of the pudding is, of course, inthe ability of the receiver to dig thatrareDXout of the pile-ups. Using a homebrewconverterwhichtranslates 10, 15and20tothe 80 meter band on the BC-348, weworked20newcountriesintwo weeks. Forthemorescientifically inclined brethren, the"before" and "after"if responsecurves areshown inFig. 10. Needwe say more?. . . W2LTcrystal filter in, advance the phasing con-denser until it is half meshed. Then adjustthe trimmer Cp untilthenoisehas atinny,ringing sound. Then peak up theiftrans-formers (top and bottom) for theloudestnoise with this characteristic sound. Thiscompletes the rough adjustment.Forthe final if alignment, youwill needastable signal generator, preferablyone thatcanbemodulated. Wefoundthatthe vener-ableBC-22l-AKisperfect for the job. Also,you will need an ac voltmeter (say o-5V)that canbebridgedacrosstheaudiooutputas a tuning indicator. The object of theexerciseis tofind theexactseriesresonantfrequencyofthe crystal After this has beendetermined, the signal generator is parked onthis frequency, and the final adjustment ofall if transformers ismade.Couple the signal generatortothemixergrid throughagimmickcondensermadebytwisting two pieces of insulated wire to-gethersotheyoverlapfor about one or twoinches. Theendof onewirecanbe strippedand wrapped around pin 5 of the 6SA7mixer tube which is then replaced in itssocket. Tune the signal generator slowlythrough 915 khz (with the modulationonand the bfo off) and carefully adjust thefrequency for a maximum on the audiooutput meter. If youhave hit itonthe nose,the phasing control can be varied + I 0degrees rolation without appreciablyaffecting the output. Peak up theiftrans-formers. Repeat the procedure to doublecheckthealignment. Acoupleofhints: usenomore couplingfromthe signalgeneratorthanis neededfor a goodoutput indicationso the ifchain won't be overloaded; also,short the antennabinding post tothe groundbinding post to prevent the reception ofspurious signals which may interfere withthe desired signal fromthe generator.Before disconnecting the alignment set-up, try testing the action of the phasingcontrolinnullingoutaweak. signal near thepeakfrequency. Detunethesignal generatorabout I khz higher than the alignmentfrequency. Slowlytune thephasingcontroluntil the output drops drastically. Thisadjustment is very critical and takes afinetouch. You should get at least 15 - 20dbattenuationasthesignaldrops intherejec-OCTOBE R 196961Grounded GridRalphS. Yeandle, W21KP. O. Box 252Schoharie, NewYork 12157Filament Chokes'Duringthecourseof construction of mylinearamplifier employing two type 4-400 Atubes, the market price of a 30 amperefilament choke was suddenly raised fromabout $9 to around $25. Whether this was dueto the high price of copper, theenamel onthewire, or becauseabeautiful doll neededa new diamond, did not interest me one iota.It was high time for ingenuitytobe sum-moned forth.A lookat thedriving impedance of thosetubesin this typeof operationindicatedavalue of 300to500ohms or thereabouts,which washalvedfor twotubesinparallel.Thismeant that thechoke impedance at thelowest frequency tobe used should haveavalue of, say, five times this inorder tomaintainalow rf loss through the choke. Sowe are then talkingabout a chokeimped-ance intheorderof1000ohms. Onecouldwind this kind of a choke with his eyesclosed unless he considered the currentrequirement of the tubes. This required averyheavy wire, size No. 8orNo. . l 0, andeventhenagoodfractionof a volt could belost between the filament transformer andthe tubes. When a coil takes on theseproportions, there must be a better way thanrolling your own.Thesolutionwas easy. Mount thetrans-former oninsulators at least ~ " thickness,thus isolating it fromall chassis grounds.Thenconnect thesecondarydirectlytothetubesusingwireof sufficient size to preventanyappreciabledrop in voltage to the tubes.If you find that the transformer has anelectrostaticshield, asdidmine, disconnectit andlet it float. Thesecondarycentertapmay be connected through a choke toground by employing one of those smallmultiple-Pi types, but if youare particular62about getting toomuchderesistance in thiscircuit, and about wasting a good highimpedance choke where it is not needed,then here is a place where a simply con-structed device can be used. Oneof quiteadequate characteristics can be made on a1"diameter formabout 3" long, wound withabout No. 30 wire. Aprimarychokeinthe110volt line was wound in bifilar fashionwith No. 24 wire, I" diameter and about4*" long. The heavy capacitance existingbetween primary and secondary. comingabout either by direct couplingor via thecore, indicates that thereis littledifferenceinthemagnitudeofthe rf voltageoneitherwindingand therefore thesame amount ofchoke impedance is needed for each.Formex insulated wire was used on thebifilar and no indication of breakdownbetweenadjacent turns has beenevident inthe three years of use. If preferred, twoseparate line chokes may be used in theprimaryin which case each can bephysicallysmallerthanthebifilar. A .01mfd by-pass isused fromeach side of the line to ground, onthelinesideonly. The above dimensions areapproximate and have served well in myamplifierthroughout 80to10meters. Theywere duplicated more or less for anotheramplifier using 2 type 813tubes. Of course ahighquality coil formmay beused, but inthiscase the circuit impedance is sufficientlylowto allowan old broomstick, hammer-handle, or a dried out sapling to beused - even at 10 meters.So the $25 with which I almost partedwasusedfor muchmore important things.Cometothinkofit, 1 believethat1 boughtananti-gravitymachinefroma door-to-doorsalesman.. . W21K73 MAGAZINEMini-AFGenerator forthelaboratory orhamworkbench. 10 to 100-,000 hz in four bands, sineorsquarewave. Worlo'ssmallest. 7Y," x 3%' x4" 2Ibsl Built-in ACpower supply stabilized to O. ~ %The output is maintainedat minimumdistortionandconstantlevelwithFET oscillator andthermis-terandheavyinverse feedback .torized PCtest equipment. Now a complete servicelab,including RF and AF signal generators, is buillinto a case aboutthe size of an old VOM!MINIATUREAFGENERATORThe day ofthe great bigpieceof test equip-ment ispast, made a memoryby moderntrensis-TESTMINIATURE TEST LABORATORYONLY $59.95.. -.':-. I- .This is by far the singlemost valuablepieceof testequipment. Built in meterfor measuringgainofeachstage under test . Easy tofind weak or defectivestages. Output speakerbuilt in or to VTVM orscope. Noline cordsinceitisselfpowered. ONl VModel SE350 Signal Tracer $22.50RFFieldStrengthMeter1-400 mhzComes with a-sectton antenna and earphone formodulation checking. Invaluable for tuning anytransmitter. Magneticbase formobileuse.Model FL-30 ONLY $8.95Model 6803 AFGenerator52 Ohm1 KWSWRMeterISimpleInexpensiveEffective$14.95ModelSE-405ACVoltmeter DC VoltmeterOhmmeter MilliammeterRFSignal Generator AFSignal GeneratorResistance Substitution Capacitance Substitution9VDC Supply AFFieldStrenp,thSelf Powered 7%"x 3%"x 3l4", n ~ l b s .Thanks totransistorsandprintedcircuitsyoucanholdthiscomplete lab inonehand. Not longagothis would have been 8 whole shelf full of testequipment. 455khzgenerator foraligning11'5,.400hzgeneratorfor audio circuits.Plus anormal yOMand A&C substitution. Field Strength meter fortuning transmitters. Everything in onesmall box IModelSE-400 Mini-Lab ONLY $25.00Buy DGPMiniature Test Equipment fromYourLocal Distributor or Order Direct Mail fromREDLINE CO., JAFFREY, NH 03452. Pleaseallow a little extra forpostage charges.Distributors:Write forour distributor pricesManufacturers Reps: Weneed you-WriteEnclose check orMO for:IUIIllS1EI III"alIC __I_.nIHCallMiniature TestLab $25.00Miniature AFGenerator $59.95AFMeter $8.95SWAMeter $14.95Miniature Signal Tracer $22.50Power Supply $16.95ZipooooooAddress ---tWorth itsweight inbatteries. I nvaluable for tintingtransistorizedor Ie gear. Savesits priceinbatteriesCity State -----I for long range operation of radio1J.. cassettetaperecorders, etc. 0 20 VDC@1502uurna. Meteredandregulated. .Model SE-l00 Power Supply ONLY $16.95Name -IOCTOBER 196963IGeorgeWilson W10LP318 Fisher St .Walpole, MA 02081Equipment Cabinetswith StyleSIDEVIEw-_.--- --... - - --REARCOVER1-_ ASAPPROPRIATE

VIE W3/4 'SECTIONAL VIEWFRONT VI EW1'- - 0SCREWINTOPANE l STOP --(IF NECESSARYIontheheight anddepthof your cabinets sothat theywill present a uniform appearance.Thequarter-inchplywood recommendedforthesidesofthecabinetswili provideplentyofstrengthforeven relatively large cabinets.However, if you have asource ofanotherthickness or another material, it canproba-bly beused.Building SuggestionsThe quarter-inch plywoodsidesand topand a three-quarter-inch pine or fir basematerialsappeartobeanideal combinationof availabilityandusefulness. It is suggestedthat thesematerialsbecut onatablesaw ifone is available. Atable sawwill providesquare, relativelysmoothedgesthat canbeassembled without further furnishing. Solittlecuttingisrequiredthat any friendwhohasasawshouldbegladtomake the piecesforyou. Cut thesidesandtopfroma singleoMost experimenters and homebrew equip-ment builders settle for commercial cabinets,boxes andchassis to house theirelectroniccreations. Thisarticle will describe amethodof building cabinets that are simple andstylishandthat canbebuilt ina wide rangeof sizes. Thesecabinetshaveminimumcostandyet havethegoodappearance necessaryto make your radio room and workshoplook highly professional.Thesolutiontothecabinetproblem is tobuild wooden cabinets like those shown inthe photographs. Considerabledevelopmenthasgoneintothesecabinets. At thispointIfeel that maximum simplicity has beenachieved without sacrificing utility and style.Theaccompanyingdrawingsandthe textthat follows describes a"type" of cabinetratherthanaspecificcabinet. If this type ofcabinet is attractive to you, alittle fore-thought isin order so that you mayadaptthe design to your own needs andtothemost readily obtained materials. Thewidthdimensionwillvarydepending on the equip-ment that is to be housed. On theother-hand, perhapsyouwill want to standardize6473 MAGAZINEpiecethat has been cut to thefinished depthdimension. Thiswill assurethat thetop andsides are all thesame depth and that theywill match perfectly when assembled.Thepanel stopsin the upper corners maybe glued tothetopofthesidesasthefirstassembly step. Use white glue and half-orthree-quarter-inch brads to fastenthe variousparts. Next, attachthe sides to thebase and,last, attach the top. Use the white gluegenerously, but wipeany excess off exposedsurfaces witha damprag. Whentheglueisdry- about an hour, the exposed surfacesshould be sanded to eliminate any ridgesbetween the sides andthe top and toprovideasmoothsurfacefor finishing. A belt sanderis handy for this operation, but handsandingis easy andadequate.The assembled cabinet should be sealedwith shellacoracommercial sealer. It canthen be spray painted using one of thequick-dryingenamels orlacquersthat comeinspray cans. Buildupthreeorfour coats.Each individual coat should consist of sev-eral light sprays withspecial attention(re-sprayings) being given to any spots thattendtosoak up the paint. Allowat least ahalf-an-hour betweencoatseventhoughthelabel will claim that the paint "dries inminutes". The last coat should provide ahigh-glossfinishthat will beanasset toanyshelf in your house.Nothinghasbeen said about choosing thecolorfor your cabinets and very little willbesaid. However, don't overlookthepossibilltyof choosingoneor more bright colorsthatwill fit with your decor. I use a "mix-and-match" scheme. In the workshop,cabinets are "colorcoded". Power suppliesare redandtest instruments are black. Thespeaker that goes with the commercial re-ceiver in the radio roomis blacklike thereceiver.Panelsmaybemetal. wood, "hardboard"OCTOBER 1969negatives forp. c. boardsBIGELOW ELECTRONICSBLUFFTON OHIO45817or a plastic such as Bakelite dependingontheneeds oftheequipment tobehoused inthecabinet. HardMasonitewitha couple ofcoats of a sealer like Firzite makes anattractivelooking panel that is easily workedusing woodtools.Panels for speakercabinets canbemadefromperforatedmetal orwithopenings andgrill clothintheacceptedmanner. The backof acabinet maybe left open; closed tightlywith wood or metal; or it may beclosedusing perforated metal or screening.Openings in the back and sides may beprovidedfor cooling. Heatingofthe cabinettopcanbelessenedbycementinga piece ofaluminum foil to the inside of the top.Thefront panel canbemountedinmostcases by using three-quarter-inch round-head-wood screws through the panel into thethree-quarter-inch base. The panel stops atthe top will prevent the panel frombeingpushedin. If added security is desired, woodscrews can be used in the upper panelcorners. If anextra long cabinet is built, it isrecommended that anadditional panel stopbe installed on the inside of thetopat thecenter of the cabinet.UsesCabinetsofthe sort described hereinmaybe used formany types of devices.Power SuppliesTimersSpeakersSignal GeneratorsBridgesClocksChargersMetersReceiversTransmittersStanding Wave MetersIntercomsThe listabove is just a fraction of the use,that can be found. These cabinets free theequipment designer from size limitationsand, at the same time, provide himwith ~source of easily made cabinets that wilenhance the appearance of his equipment....WIOLf65Richard J. Zach WB2AEB33 Pike Place, RFD-4Mahopac, NewYork10541VHF-FM:Advantage s andPart IPracti cesWhen you operate, what do you want in asyst em? You maysayreliability, qualityofequipment , as well as ease of operation.Perhaps you have as insatiable thirst tot inker wit h equipment t oget theabsolutebest performance. VHF-FMcan sat isfy allthese requirements and more.As you may know, VHF-FMisgrowingfa sterthananyothermode. Whyhas such arelatively newconcept enjoyedsuchpopu-larity?Perhaps wecan answer thi s by askingstillanother quest ion. What isVHF-FM?Ofcourse, youcould say that youFMaVHFtransmitt er. But VHF-FM (or just "FM"fromnowon) isalso anentirelydifferentsystem of communications.About 75% ofall FMactivity is operat edfromthe mobile. The rigsare surplusgeartaken out of commercial service (taxis,poli ce cars, fire trucks, etc.). When youpurchase these rigs, they come with allaccessories ... transmitter, receiver, powersupply, mike, speaker, control head andcables, but lesscrystals and ant enna. Theyseldomrun over 60 watts, with most rigsrunning 30 watts or under. Antennapolarizationis always vertical. FMdeviationis usuallywide-band(+15 khz)but there area fe w scatt ered narrow-band outfit s (+5khz). The trend today is toward narrow-band operation, though. You can get acomplete rig for as little as $25, but theusual pri cerunsbetween$40and$90 whenobtained froma dealer. The possibilityofobtainingtheusedequipmentdirectlyfromthe commercial user should not be over-looked.As noted, just about all FMactivity iscrystal controlled and hence, operates on66"channels." Because of accepted channels,repeater stations can be utilized. Suchrepeater stations, usually located on highgroundwithhigher power, receive signals onone frequency and simultaneously retrans-mit the received signal on a differentfrequency. Going through a repeater, youcancover a50mileradius using just a onewatt walkie-talkie. However, in speakingwithotherhams, Ifindthat there is one bigmisconception aboutFM. It seems that quitea fewpeople think that you mustgo througha repeater. Quite to the contrary. As amatter of fact, Insoutheastern NewYork,mostFM activity is "direct ," without the aidof a repeater.Anotheradvantageof channelizing is thatmoststations can, anddo monitor. When anFM'ergets out of work, ongoesthemobilerig. When he gets home, ongoes the basestation. After a while, you know whenthe different stations are monitoring. You arenowapproachingthereliabilityoftheland-line via ham radio.Emergency communications is one ofFM's strongest points. The fact that allstations are always on frequency and FMreceivers are not susceptible tolightning orignition noise provides for an extremelyreliablesituation. With some repeaters, if thecommercial power fails, an emergencygeneratorautomaticallykicksin. Theabun-dance ofmobile andportableequipment aswell as the fact that much of this wasdesigned originallyfor emergencyuse, givesFM theupper handinmost any emergency.Operatingprocedure onchannelized FMis somewhat unique. Insome parts of the73 MAGAZINECODEMASTERtapes are 2track monaural; ava il able intwo sizes: Jinch reel ( H ~ IPS) and 31;Hnch reel (11'. IPS).Will playon anybut full track machine. SPECIFYboth typ. and,II' of tap. you want. Any tape, $5.95 postpa id USA4th class. Any two tapes, $11. 00: .11 three, $15.00 PPD. Immediate delivery. CODEMASTER tapes are made only byf' lckeri na: RadioCompan" P. O. BOl 29A.Porbmouth, R. I. 02871. Satisfaction Euaranteed. neeters: inquire.CM2: For Edr. Class licensestudy. Mosl ly slraiEht ted; somecodegroups. 1hour al 20WPM;1/ 2 hour each II 25and30WPM.For real QRQ, play this lape attwicespeed!eM-1 1ft:Anintermediate tape, especially for General Class eumsludy. No instruct ion; just prae-uee. 1,1 hr II WPM; I hr 14 WPM;'12 hrat 17WPM. Includes codedgroupsandstraighltext ,CM.l: For the bea:inner. Aeem-plete course of inslruction is onthe tape. Practice material at5, J, 9 WPM. Prepares you forNovice exam. Includes code groupsandpunctuation.YOURTAPERECORDERIS READYTOTEACHCODE!That ' s r ight! Your t ape recorder is ready t o help your code st udy.The CODEMASTER t apes give you professional instruction via your ownt apemachine. Nowgeneratedbydigital computer, t heCODEMASTERt apes areunsurpassedfort i mingaccuracy, Whetheryou'rejust start.ing, going for your Amateur Extra, or somewhere i n between, theCODEMASTER t apes are yourbest code- learni ngbuy! FindyourCODE-MASTER t apebelow!-Dept. H, 1 t ~ 2 3 JamaIca Aye. , Hollis, N.Y. 11423Modol407$34.95.pd.THE BEST2 METERCONVERTER:-::JAll leoding linesof erneteur geor:We give best trode-in allowoncefor your gear on newequipment :Call us for the best deol:WEPAYCASH fOR HAM&CI RADIOSCALL ORWRITEBOB'S AMATEUR ELECTRONICS927N.W. 1st. St.. OKLA. CITY, OKLA. 73106Phono 405CE56387VANGUARDLABS"THE COMPLETE HAMSTORE"WHERE YOUR DOlLAR BUYS THE MOST144-146MHz I... 28-30MHz outor 146>-148MHz w""as.codcrystalA full deecr-int lon of t bill fantastic converterwould fill this page, but you ca n t ake our wordfor It (or those of hundr eds of lIatisfied users)t hat it's t he best. The reason is et mnle-cwe usethree RCAdual gate MOSFETs , one bipolar, and3 diodes in t he best dreuit ever. Still not eon -vtneed TThen send f or our free catalDI' and getthe full dl!llcri ption, plus photoll and even t heschematic.Can't wait TThen send ue a postal money orderfor $34.95 and we' ll rush t he 407 out t o you ,NOTE : The Model 4.07 is also avail able in an yf requency combination up t o 4.S0 MHz (some athigher prices) as Hsted in our catalog.N.wYorkCity. rId St. t. rati d.nts .dd local w itn.country, thecommercial "IO-eode"isused .This does provide for quicker QSO's, butthisaspect of operation has not been usedtoany extent intheNewYorkCity area as wellasmanyothers. "CQ" is never heardon FM,sincet hereis just noneedfor it. All stationsareonfrequency, sonolongcall isneeded.Youmight simplysay, "Thisis WB2AEBmonitoring nine-four," and that's it. Ifanybodywants togab, they'llanswer. Sincethechannelsarewell known, when referringtothemyousimplysaythenumberstotheright ofthe decimal point. Thuswhenyourefer to 146.94 mhz you say "nine-four."When referring to 52 .525 mhz you say"five-twa-five."Even where six-meters AMmay reign king,two-meters is often wherethe FMham stays.On a national scale, two-meters isalso themost popularchannelizedFMband . 146. 94is the national two-meter frequency withother side channels such as 146.76. Thenational 6-meter frequency is 52.525 mhz.Thereisalsoanational ten-meter freq uencyand this is 29.6 mhz. There are about 300hamsonthis frequencyandmore are joiningeveryday. Thisbandispopular becausetheskip comes in more often than the VHFbands. Toget on teu-metersFM, you simplytune the rigdownto29.6 mhz instead of52.525mhz. The low-band rigs tune from25to 50 mhz often with fewmodifications.Asfor UHF, the *meter bandis popularfor your own "secret" repeater. To theFM'er, six-meters is called "low-band,"two-meters is called "high-band,"whilethe'A meter band is called "450" or simply"UHF"As you can see, FM is different.. . . WB2AEBOCTOBE R196967Robert L. Grenell, exW8RHR3926 Beech StreetCincinnati, Ohio 45227Bring- BacktheQMultiplierFig. 1. The Grenell Q-multiplier. L 1 &L2canbeeither theHeathcoi ls, ifyourebuild,or Miller numbers 4414 and 4409 respec-tively.,EPTH,,,00'zz\-2200~ 5,.t,"-O-"' f'02201< ,.U00', ,,r- ,RIRT """---,..-J'f--~,s1STIf'a.a."'"'0 ,.'"-_ 10wavepieceisslippedintothe \1to,l,)(DRIVEN I" 11 OR OTHER1J2' XI9"AjUM MATERIAL ':_" ' ::>WOOl) SCREWS...... , \ '1/4),. TRANSFQRhlERBOOhl IINSIDE DRIVEN ELEhl II A PIPECLAhlPSFig. 2. Details ofdri ven element."o. . 35"OZ' 35 314"0 3 36 "'O"_I-'O"---JREFLECTOR ELEMENTS4 9" 10SPACEO "'AX OF e",,',,'ADJUSTFOR MAX 03GAIN--// '1/4114" )( 4"8 01..TADJUSTFORMIN..,- 0"'OHMM __COAX-3/ 4"ORI" AU/fll .- -Drill holes in the tubing for bolting the58-inchlengths of cedar, approximately281>inches either side of centerand drill thesamesizeholes (topassI>x 4" bolts) in the58-inch cedar strips about 39W' fromoneend of each st rip (the ends that will formtheapex). Drill holes, for force fitting thealuminumclothesline reflector elementsinthe cedarstrips every 8 inches, measuringfromthe apex orcorner end(youmayputan additional element at the apex if youwish - I never got aroundtoit). Straightenthe clothes line byanchoring oneendtoatreeor otherfirmobj ect andtugging gentlybut fir mlywithacaronthe ot her end. Youwill windup withanice, straight piece ofaluminum wire from which to cut your49-inch reflector elements. Force the ele-ment s intotheholes inthe cedar strips untilthey are halfway through. I put a drop ofweldwoodglueoneach side of each elementand have never touched them since.Animportant thingto' remember at thispoint : don't put the reflector elements inuntil youhavelayedthisout onthe groundwiththe reflector framestrips loosely boltedto the mast , because you will have todrillanother hole in the mast for a bolt tosupport the boom. Theboomwill bemadeintwopieces so that thedirector elementswill beinline(horizontally) with the drivenelement, andthedrivenelement in line withALl. WOOD PARTSI II 2CEOARYOU CANPUT TCUl, __TURN STl l. E HERE -7473 MAGAZI NECQCQ CQde B&WTVl Low Pass Filter t KW85 dbonTV bands, 52 ohmscharac. imp.,80-10mtrs. 1, "'x3"'x2".# 425 $22.50Coax Switching Sureand EasySinglepete. 2 positi on. UHF-typeconnectors,radial mounted .# 5S0A-2 $10.20Singlepole, S posit ion, UHF-typeconnectorsmountedonbackpl ate.;t590G $11.55... ..B, I"Coaxial Dipole AntennaI Connector . Rugged,WatertightWeatherproof, strong. Al umi numhousing, rustproof parts, steati tei nsul ation. Dependableconnectionsunder all condi tions.# CCSO $6.60wave dipoleleavingthefour-foot sectionofcoaxfor feedline.You can solder your coax feed directlywithout the four-foot piece, but I like theconvenience ofa short length fortesting andpruningpurposes. When I builtmine, 1 madeeach driven element about 19 3/4 incheslongandmounted themonapieceof scrap~ inchplexiglass. AnygoodH. F.insulatingmaterial will do, evenbakelite, but 1 preferthehighpolish of theplastic for our salt andweather conditions. After mounting thedrivenelement, I pruneit t o 145mhzusingmygriddipper, animpedancebridge,andacheap (95c) tubing cutter. The final touchup was made by sliding the element backand forth for lowest SWRand doing t hesameforthedirectors forhighest front gain.Thesketches should makeeveryt hi ngclear.That about does it. I'msurethat ifyoufoll ow the pies and diagrams reasonablyclosely, you will wind up wit h as good asignal squirt er as mine. Goodhunting on "2"and "73"5.. . . WB4FDQReferences" I nfinite I rnpedance Match," 73, March. 1963p. 20.1965ARRLVHFManual . pp. 208and225, Figs.9-31.Write for complete catal ogand pricesBarker & Will iamson, Inc.CanalStreet, Bristol , Pa. 19007.(215) 788-5581.The unit is assembledon a 5 x21'>inchpiece of phenolic board. All the part s exceptthe I megohm pot and 27 k resistor aremounted onthe underside of theboard.RayEzelle, WA8YWKASimple CodeOscillat orThis code keyer has awiderangeof fre-quenciest opleasethet astesofanyonewhowants to learn the code. It uses very fewpart s andcanbehousedinthe basewiththekey. Thecircuit usestwoinexpensivetran-sistors, oneaPNP, the ot her anNPN; almostany type canbe used.~ ~R 48hr.DELIVERYORDERDIRECTwithcheckor money order toS pec ia l QuantitvPricesto Jobbers andDealers2400BCrystal Dr., Ft. My,rl. Fla. ISIO ICRYSTALSWehaveinstockoversix million cryst alswhi ch include types CRI A/AR, FT243 ,FT241 , MC7, FT249, HC6/V, HCl3/ V.etc. Send lOi forour 1970cat alogwit hoscillator circuit s, listing thousands of fre-quenciesinstockfor immediate delivery.(Add lOi per crystal t oabovepri cesforshipment 1st class mail; l Si eachfor airmail.)SPECIALSColor TVcryslal (3578. 545KHz) wire leads S1.60 4 tor S5.00100KHz frequency standard crvstal (HC13/U) 4.50lQOQKHlfr equency standard(HC6!U) 3.50Any CBcrystal transmi t or receive 2.25AnV amateur band crystal (except 80 meters) 1.50 4 for $5.00Any marine frequency (HC6/ U) 2.8580 meter cyrstals inFT243 holders 2.50.,.----'N,--,-",EEDCRYSTALS?80MMSPII RtoJA simplec o d eo scillator"I meg,,,2NZ33 OR AIrl YGENPURPOSEcNPNTRANSISTOR, , cNY GE NERAL, ,IRPOSEPNP , svRANSISTOR , ,,,"" rOCTOSE R 1969 75T'lLe ARRL BoardA. David Midde/!onW7ZCBox303Spr ingdale, UT 8476 7and A mateur RadioT he Annual meet ingof the ARRLBoard washeld in NewOrleans on Muy 2. 1969. fo ll owingseveral days of infor mal ga t her ings. committeemeeti ngs andsocia lizing.Aseriousattemptwasmade inthe earl y'50stohold every o ther Annual meet ingina placeawayfrom t he shadows of the lvor v Tower in theHar t ford area. Denver '54 and'65 aretwo local esof t his meet ing of theBoardand theIIQentourage . There mayhavebeenother travelsfor th isimpor tant ( toamateur radi o) affair wherethe fate of AR may be decided or at leastintlucnccd. However. most suchmeetings archeldncarIIQ.Present in NewOrl eans were fift een di rectorsandonevicedi rector act ing for his ailing direct or.Also presen t; adutch of VPs: theGeneral Mana-get-Secretary, theTreasurer andfour vice direct ors(wh o did not get thei r expenses paid by ARRL)a nd a bevy of IIQ per sonnel. Missing from therost erwas ARRL's Publi cRel ations Counsel (Item101 of t he 1966 minutes reques ts t hat astudybemadeof retai ningPRcounsel toa ttendall Boardand Executive Committeemee tings). Alsomissing-anyrepresentati ve of IIQ' s technical staff.In repor ti ng the activiti es of thi s meeting,mat erial has been placed i nassocia tedareas, eachli stedina tenta tive "order ofimpor tance"rel atedtothepresen t andfut ureof bothARandARRL.References arc madebyItemnumber andarcnotin the order Found in the mincocd minut esprepa red and distribut ed by the Secreta ry. Cate-goryheadings we re selec tedbythis repor ter.Public Rcl ati ons-Amoti on (It em 12) passed(114) that a stu dy of. and recommendations bemadefor. aformofheldOrganizationwhi chwillprovide contact bet ween HQand those memberswhose interestsdonot presentlycoincidewiththeinterests of theCommunica tions Dept.What ever became of the request for a Fi eldOrganizati on setup- made by a previous Board afewyears ago'! Such al'. O. islongover dueandbadlvneededtobrine ARRLtothefi eld!J\ ft erextendeddiscussion,duringwhichit wasalmos t tabled. It em 39 req uests 03-3) that asuita ble publica tion be writt en by ARRL (aftercons ult ation with reading specialists) directed atthe 12- 16year old gro up.The idea is commendable. T he nega tivevot esarcine xcusabl e.A unanimous affi rma tive vote (Item41) in-structcdtheGeneral Manager totakeste ps leadingto the additi on of an " int roduc t ion 10 Amat eurRad io" course to highschoolandad ult educa tionclasses.Th istooisanexcellent idea, butit will requi reheavyfo llow-up.i\ unanimous vo te (aft er d iscussion Item44)instructed tile General Manager to periodically76publish inQSTinformationonARRL' s structure,including dire ctors and SCMs, and to include aglossary of hamterminology.T his will be excellent PRand shouldenhancerelationsbetween ARRL andthe ARbody. All toofew licenses knowwhat ARRL is all about andmanycareless!Suchindifferencedocsnot alwaysinvolve personalit ies but is oftenrelated toignor-anceof basic ARRL concepts. aimsand goals. Withnew blood coming into AR. and with the everexpandingfieldsofendeavorin AR. ARRLsho ulddo a better selling job of itself.According to Item 60, a unanimous voterequested the General Manager to have the PRCounsel prepare material for distribution to pro-spective members that will convey the tangiblevalue of ARRL affiliationtothe individual.This idea , together withthat immediatelypre-ceding it, may make ARRL membership moremeaningfu l to amateurs. This PRwork is in therigh t directionsince HQhasfailedto doitsiob onthis. Follow-upisnecessary, if itis tosucceed.Item81 states that W4GSXwill be presentedwith ARRL' s 1969 Technica l Merit Awardfor hisanalysis of typical ama teur antennasusing moderncomputertechniques.\V4GSX' s work will beawaitedimpatientlybymany whohavebeen looking for atypical antenna!Maybe he hasth e answers!This reporter (the originator of ARRL'sMeri tAward) is alwaysdelighted and proud toseethisAward made as some times the Committee haspassed it over being unable (?) to find anyoneworthyof theAward. It should benot ed that theoriginal motioncreatingthi s Merit AwardincludedHQ act ions t o properly circulate news of theAward to non-amateur media in order to obtainthegreatest possiblePRfromtheamateur ' s work,whichresult edinhi s Award . SuchPRhas notbeenproperly done and much of the value in thenon-amateur PRworldhas bee n los tTheGeneral Manager wasreq uested(l tcm87)to" continueanadvertisingca mpaigninmagazineswhichmight be readbyindividual s whoarc likelytohaveaninterest inbecomingradioamateurs, inan attempt to attract more individuals into theamateurservice."Suchadver tisements shouldbeof greatvalue toAR and to ARRL. The word "cont inue" impliest hat such adver ti sine has appeared. This reporterwould be grateful fo r clippings of such ARRL-placed ads as so far they have escapedhis noticewith one except ion.Defense of Amateur Rad io Frequencies-TheDec. 31. 1968 ARRL financial report ind ica tesunder " Reserves -for d efense ofamateurfrequen-cies-S62,4 13.52. "T his is the balance of a SI 00,000 fund fur-nished ARRL's Pre sident Hoover, \v6ZH, some73 MAGAZINEyears agoandwhichhad become depleted with PRstudies and other expenses.Item30 states "on motionofMr. Chapman,unanimouslyvoted(MessersSpencer and Thurstonabstaining [italics supplied - ADM]) that, inviewofan announcement of aforthcomingconferenceof the International Telecommunications Union,the Board replenishesthe $100,000fund for thedefense of amateur frequencies. "Althoughlittle has been heard fromthe originalS100Kor thenearl yS37K spentto date, thi s fundcould become a vital weapon in the battle topreserve and prot ect our frequencies in a worldthat seems determined to take over all lowandmedium high amateur bands in their obnoxiousspreading of their own brand of propaganda.All amateurs should be keenly interested inwhat ARRLdoesandwhat it accomplisheswiththi s S100Kfund. Thisreporter hasseenlittleoftheresults except the Stanford and Waters reports.The latter, at least, was worthit! That, plussomeHQ st aff junketstoforeignlandsis what has beenseen in QST.ARRL can afford to spend almost its entireresources inorder to effect suitable safeguards thatwill help preserve and retain our useage of aUbands. $1OOK. if properly expended, can do a greatdeal of good forAR!ARRLMembership-Item42 orders that apostpaidinsertinvitingmembershipbe includedinselected ARRL publications andinQST, once ayear.Thenecessityfor such a Board directive escapesthisreporter. HQshouldhavebeen doingthisforyears. Suchamotion, or theneed for it, raises thequestion-does ARRLHQreally want ARRLtohave moremembers?More members-more work-remember? How about an ARRL membershipcontest -with prizes?This idea (Item42) shouldbring results-if it is followedup.QST- A motion to include a propagationcolumninQSTwaslost whenit was tabled(I tem66) by a vote of 12-4.Some will argue that thi sinformationappearsin other publicati ons. True, andsome have widecirculation, but what about thosedie-hards whoreadonly' QST- andneedthi s information? ARRLshould serve its membership regardless of otherpublications.Item68 requests ast udytosecuremorerapiddeliveryof QSTin6-1and, KH6,KL7andaU partsofUS andCanadaandrequeststhat theresultsofthi sstudy(byt he General Manager)bemadenotlater t han the next Board meeting.Inby-gonedays onecouldtell thedatebythearrival of QST. This reporter believes that the poordeliveryis not the fault oftheQSTandHQstaff,and offers a thought that perhaps the postalemployees are delaying QST by reading thembefore delivery! Could be potential amateurs?Maybe! If theywereARRLmemberstheywouldget their own copy and thus perhaps speed upours!ARRL-rCCMatters-This category is lengthyandsomewhat confusing. An attempt will bemadetosimplify thevariousproposalsandtheirfateatthe hands of the Board.Item13requests that ARRLpetitionFCCtopermit Conditionals or higher in the KL7, KII6,KP4andUSAinsularpossessionstousephoneon21.2to21.25mhz. Also, t hat ARRL consult withIARUregardinga futurepetition to FCC to permitphone on these same frequencies byExtras. AnOCTOBER 1969amendment withdrew the IARU bit, but theamendedmotionwas defeated. Novote count wasgwen.Item14 would petition FCCto permit Techs touse 29.0-29.7 mhz. This was amended to read29.5-29.7. Vote -14-1 with theCanadiandirectorabstaining as is donein matters pertaining to FCC.ThePlanningCommittee wasinstructed(Item19) toconsider the feasibilityofpetitioningFCCto-Expand75-fone to 3750-4000.Move SO-Novice to 3650-3700.Expand 40-foncto 7150-73UO.Move 40-Novice to 71007150.Expand20-foneto14175-14350.Move15-Novice to 21100-21200.This Item19also instructed that a report bemade by the next Annual Board Meeting. Thismotion was amended to establish liaison withIARU to evaluate international aspects of thesepossiblechanges andtoreport bythe next AnnualBoardMeeting. The amended motionwas passed.A large follow-uptag, please, Miss Blue!IFItem 37 is followedthrough andIFFCC actsfavorably, devotees of the art of EME, MSandother valued VHF/UHF pursuits will be grantedhigher power.Note t he IFs in that statement. High powerwould tremendously aid important work beingdone by pioneers in the most valuable facet ofamateur radio yet encountered and which may wellbecome our only area of activityin the near future.Item53 requests FCCtomake144-148avail-abl e for Technicians instead of 145-147. ARRLwill so petition FCC.After all somebody has to use those highlyvaluable 4 megs! It isassumed theTechs wouldhave the sameIone-cw regs as ot hers.If FCCagrees with the motionmade inItem55, potential Extras will only have to wait one yeartotaketheExtraexaminsteadof the currenttwoyears.NotetheIF. This is agood idea, and let's hopeFCClikesit. Novices andTechnicians willbenefitif the intent of Item55 is OK'ed by FCCandpermissionis grantedforTechstoobtain a Novicelicense without surrenderingtheir present licenseandwaiting one year.Anexcellent proposal will bemade to FCC thatatypewriter (providedbytheamateur) be permit-tedin copying code exams. Item73 (always a goodnumber) covers this but its originator, the well-known contester and triple-A CWop, W4KFC.overlookedpetitioningFCCtopermit headphonesover theears of aspiring examinees!Anytremblinggun-shyneophytewillwelcomeamill andmaybe,someday, headphones again..Item74 (which waspassed) requests FCCtoassign lx3 (preferred) callstoExtras who requestand pay the fee, such calls to be assigned onarandom basis.If this ideagetsFCC' snod. some Extras mayget desirable calls. Oh, for the old days ofcall-swappingandinitialsin your call andall thatsor t of thing, sans computers!MMboys will be pleased if ARRL' ssupport(Item95) leads toFCC'sapproval ofMMon7to7.1mhz.AR will benefit if MM is so allowed, asMM-working is both exciting and valuable forcontactees.RTTY addicts will probably rejoi ce if FCCgrantsRTTYoperationon28-28.5mhz(Item 96)77but thisis notlikelytobefavoredbynon-RTTYten-meter ops!This same It em96 asks FCCto move "ewonl y" operationfrom147.9-148 to144-144.1. Itshould havebeentherelong ago. ARRLendorsedFCC's docket 18508 covering this item.Although belatedly, immigrants to our shoreswill be permitted hamlicenses(after filing theirfi rst papers) if K7UGA' s bill S-1466 and SJRes 27becomelaw. ARRLapprovesthi s (Item97) bill asshould aUother Americanamateurs. Reciprocit yworks wonders!ARRLHQStationW1AW-HQwas ordered byItem 15 to establish beacon stations on one ormore VHFbands, as soon aspractical, tooperateat regularhours and on a publishedschedule.This recognition by the Board ofthe impor-tance of VHF in the ARRL program, althoughbelated, will beappreciatedby all amateurswhorealizethenecessityforheavyHQparticipationinVHFresearchif ARRL is to keepup with thestateof the art andadvance VHFj UHF. Thisreporterfirml yrequests t hat ARRLput an EME station ontheair, without delay!ARRLHQshouldleadtheway-notfollow the crowd!Item 21 would have moved ARRL' sWIAWcodepractice andbulletintransmissions out of theExtraClass portions of thebands, butthemotionwas defeated.WlAWshould be operatedonthe border (intheopinionof thi sreporter andothers) betweenthehighandlower class segments, where practical.ARRL' sargument that WIAWisnotafrequencystandard station may be true, but perhaps theComm. Dept. should investigate 1969-typehigh-stabili tytransmissionpossibilities. Few stations areequippedwith25-khzmarkers (even if they have acalibrator) and WIAW could help them knowwhere theseborderslie.ARRLcouldnot beheldresponsible for a legal WWV-type frequency ac-curacy, butbeingnear theborder (ano-mans landfor the holders of the lower classes of license)could be a boon forall.Item 49 (debated and fi nally adopted -vote14-2) callsforWIAWtomakeasixmonths trialrun of arepeat oft he0230GMTscheduledcodepractice at1300 or so, five days a week.Whywouldanydirector (twodid) vote againstsuchanidea?Maybethese two didnot wishto riseat1300to improve their code.TheARRLBoardhas consistentlypersistedinusing an irritating practi ce of "referral to acommittee for study," or ot her delaying tacticswhenfacedwitha st icky probl emwit h whichtheydidnot wish to cope or make a firm decision.Item 67 is just such a delaying tactic as itauthorizes acommitteetoworkwiththeOSCARgroupand Foothills College in California to investi-gate the establi shment ofajoint ARRLjOSCARstation at OSCARIIQ.Is this to be the "west coast official ARRLstation" mentioned in League Lines, June, 1969QST or is this to be the $1500 ARRL SpaceStation?The Electronics group (plus able volunteersfromindustry) demonstrated theirmany capabili-ties and abilities in the well-executed OSCARprograms t o which ARRLgave lipservice, someQSTspace. andthe ARRL Technical Merit Award.Thi s r ep orter believes that a jointOSCAR/ARRLstationwouldbelike the infamous"horse-rabbit" meatloaf, madeof equal parts, onehorse and one rabbit. Name thehorse OSCAR.78The ideaofawest coast locationfor eitheraWIAW-typeoperationor aSpacesta tionis merit-ori ous and should implemented without furtherdelay! Yes, Virginia, thereIS a west coast !If thi s is the HQ' s answer t o the1967(Item24)directive allotting $1500 for an ARRL SpaceStation, then whywait any longer?Thedirector of the Pacifi cDivi sion(inwhichOSCARHQis located)is to he commendedforhisfortitudeandsuccessingetting a "study" ordered.But, whyast udyonawest coastARRLstation?Therehasbeenadireneedfor suchafacilityformanyyearsand it will be welcomed by all who livewest of t he Hudson!TheBoardrecognizedAMSAT(seeJune QSnand OSCAR by (Item 99) appointing liaisondir ectors to these timely andvital programs.However, by their omissionofNASTARtheyindicatedeither their indifferenceto the placing ofahamrepeater ontheMoon, ortheir ignorance ofNASTAR, or both.SI500 for an ARRL Space St ation? ManyVHFers have antennas that cost that much.ARRL' s stated worth (Dec. 31, 1968) was$1,244,288.45!Is ARRLreallyinterestedinVHFornot?ARRL and VHf Repeaters-the modusoper-andi of the Board can not be more clearlydemonstrated than in the progressi on ofagoodidea toaweakone-as showninItems 20, 38, 51and89.Item 20 (tabled) comprehensive reporting ofand aninterest inVHFrepeateroperationbyHQpersonnel andin QST space. Itern20 also called fora sect ion of the ARRL H'Book to cover VHFrepeaters and their operations. This motion waswell organized, vitally needed by thosewhogettheir kicks formthi snewest facet of hamradio, aphase that is rapidly growing in popularity andusefulness.Item38(tabled by a vote of ARRL' s President ,aft er a tie vote by the directors) called for aseparat eVHF REPEATERhandbookto be writtenandpublished by ARRL.InItem51 thedirector who madethe proposalin It em20 (apparently in a desper ate effor t tosal vage something fromhis goodidea) amendedhisoriginal motion, albeit emasculated, to requestQSTtocarrynews ofVHFrepeater activities in aprinciple subsecti onofTheWorldabove 50 MC.This amended motion was then passed.The same directorthen proposed (Item 89) t hatARRLincludea sectiononVHFrepeaters inthe1970 H-Bk. This motionpassed.Notethat Item 89calls only for a section inthe'70 H-Bk.Yourattentionis calledtoIt ems 20-38-51and89asastudy in Boardprocedure, whenfaced withHQoppositionandBoardindifference! This st udyshould be entitled- "how to have a good idearuinedwithou treallytrying! "Thereporteris surethat ardent VHr repeater fans will have less than ahuzzah fortheBoardonthis matter.Item61 authorizesthe General Counsel tofil ecomment and to petitionFCCto impliment thereport of the VHF Advisory committee withconsideration given the sta tus of various relatedrule-making procedures nowpending with FCC.ARRL-RTTYMatters-ARRLapproved(Item17) FCC's Rm 132 (pending) permitting RTTYoperationat 60, 75and100 wpm. Goodthinking!Director Affairs-Several motions were maderegarding direct ors, theirduties andother matters.73 MAGAZINEDept. H, 19623JamaIcaAve ., Hollls, N.Y. 11423Model 407$49.95ppd.THE BEST3/4 METERCONVERTERVANGUARDLABS430.0432MHzIn. 2830MHz o"torupto440MHzwIthadditional crystals.available at $4.95 eachA f ull descript ion of this fant astic converterwould fill this page, but you can take our wordfor it (or t hose of hundreds of s a tis fi ed users)t hat it' s the best. The reason is s imp le--we usethree RCAdual gate MOSFETs, t wo birlan, and3 diodes in the best cir cu it ever. StH not con -vinced? Then send for ou r free ca t a log and getthe full description, plus photos and even t heschematic.Can't wait? The n se nd us a postal mone y orderfo r S49.95 and we'll rush t he 407 out t o you.NOTE : The Model 407 is al so available i n a nyfrequency combination up t o 450 MHz (some atlower pri ces) as listed i n our catalog. NewYorkCity a nd State residents add loca l sales tax..\\I H.; U \ L I..... I!ot ..> .U" .. r . ta.UI.Ir'\l;t s WI ,UIl 5 '\ 11l\ u"'d 1!oI 9 .UUtI It 100.\ .....,,9. 00&< W 5'\ 1-11; V H) .. I!U.H I', W Il ..., .. . !I;J, OO SIt1 50 1t5.01l PSlt,Olt l' !l,( l(l...." :l!l. OO,lr, !! V tO .. , :I!/ J IO SIt(,ou 22",Oll 'NOllC1. H ; G SX117 . , . .2t5,01l ... " 0 NATIOSALKw. 1 25.00 r ra NC ..> . 69.00"11000 795 .00...110.00 :>OC I 55 99.003 10VFO -19.00 NCUli 69.0075_\ 2 2 19.00 \ 1It" 2 -1 9 .00 NC I 09 50.007 5,\ 3 29 5 .00 H!:i150 115.00 HIt050T 129.007 5 ,\-1 ... 395.00 II 5 0 189.110 SCX5.\b.rIlI1395.00KWS I -1 9 5 .00239.00 NCXA ..... 85.001 til ,00 II 180,\ C .299.00 NCX5 VFO 149.003t V:! I 25.0(} 51' 0 0 .....2 25 .on NCX500 &U,SI 275. 0 11 .HEATH KIT ,\ C500 , .. -149.00DRAKE T X l 9\J.(HI 1'OLY.CO\lM2C I 75.ll0 D X 3" 29.ll0 PC6 1 7 5 .002RIt 2 BQ. . 199,llO G P11 10 .00 1'C6&2 1 7 5 .00E1CO DX411 3 4.00 RME147 W.OO DXlOO 39.00 VHF" 152,\ .. 3 4 .00ELDICO H W29 A 34.110 R.\If,: 45.... 49.00Vto11 15 .110 HDII 10.00 R.\IE4300 . . 69.00TR I 100.00 II GI O 2.,1 .00 R;\I E D B2 3 .25.00ELMAC H.\ 20 79.00 R EG E NCY1' ;\I R8 . .. 69.00 HX 30 1 2 5 .0 0 H R 10;\I o n ..59,001' ;\I R7 39.00 D X60B 69.110 S WA N EI.. T ub 4 -&.3Mc BC-457 I 6 ,96 .. .. '1B.9& j ' , .966 .3 _7M C., BC 56 .. .. 696 895.., 12 .9 57 -9 . 1Mc BC_4S9 , 1795 19.50 23.502 .' -3M e.... . .. ".T18 " , 9 .95 ... .. ... .. .. .. 11 .951 -4 ....c -- .. . . . .. T 19. , . " 0 50 . __ 12.SO.. .. ,,, .. ,, 16,95BC 906 FREO METER. l...... ' l y IY I'"10Me Com"'''' '' '''' ' '' .on-, ,. ..n . ""n".' 0" , ni11 Ci1" h , i1 I ,On .00. All menU F0 n our .... anho\l,l", ;,\ YC. All me n-h andlse subject t oprior u kl>r il l' G& GRADIOSUPPLYCOMPANY778 LeonardSt., NYC10013.. Ph. 212267-4605CUSTOM TRANSFORMER D ESIGN & MA,NUFACTURE\ \ 'r ilp t orl Wlwe",.puGn)SIL ts. Sendonlfck. mol IndplypoIl ..... n COOplllSOft I rnnlOf sendfuU pnco rorPOII 'p-',d Compl.t. , n.nll"oonl lneillded.WESTERN n.ec RONlCS ne I , bl'IIU . "'47OCTOBER 196995-Heising modulationcan be lookedat ineither of two ways. We'll try both: Tocompare it to the picture of series platemodulation which we've just presented, intheabsenceofmodulatingsignal themodu-lated stage gets full dc power from thepower supply. Whenthe modulatingsignalgoes positive, it adds tothe de power andthe series choke prevents it fromaffectingthings onthesupplysideofthechoke, butthe modulated stage gets more de thanbefore. Similarly, when the modulatingsignal goes negative it subtracts fromthepower level on the modulated-stage sideofthe choke, and the choke prevents thesupplyfrommakingthe level up. Thustheeffect onthemodulatedstageis the same aswith series modulation.The otherwayof viewingHeisingmodu-lation is basedonthebehaviorofvacuumtubes. Both the modulated stage and theamplifier producing the modulating signalare fed from the same power supply,through the same series choke. When nomodulatingsignal is present, bothtubesarefurnished the same supplyvoltageandeachdraws the current determined by its ownoperating conditions.When the grid of the modulating tubegoes less negative, that tube draws morecurrent. Theadditional current throughthechoke produces avoltage dropandreducesthe voltage available for both tubes at thesame time. Thiscutsdownthepoweravail-able to the modulatedstageandsoreducesitsoutput. Whenthegridofthe modulatingtubegoesmorenegative, the tube draws lesscurrent. The reduced current through thechoke releases energy from the choke'smagnetic field and raises thevoltageavail-able for both tubes. The modulatingtubehas nouse forthe increased voltage, sotheeffect is to raise the power input to themodulated state, and thus increase output.This second viewpoint indicates that alarge part of theactionofHeisingmodula-tioncouldbeaccomplishedbyusing alargeresistor instead ofthechoke - andthiscanbe done. In low-power equipment wherebothspaceandcost are important, Heisingmodulation with resistor instead of chokecanbe used. Thepercentageofmodulationobtained when this is done depends uponthe ratiobetweenthecurrent drawnbythemodulating tube and that drawn by themodulated tube. If the modulating tubedraws less current, modulation percentageremains comparatively low. If the modu-lating tube draws more current than does themodulated stage, though, it's even possibleWAVEFORMS200 __==-,-__

0-----200 _--,..... _CD8. FAOMPOWERSUP9t.y"T"BYPASS..... CAP "AF PWRFor such a scheme towork, the modu-lated stage's output power level must bedetermined directly by its de power inputlevel;theamount ofinput signal fed into itsgridcircuit must not be able to affect poweroutput. As it happens, a ClassCamplifierthat is drivenslightlyharderthannecessarytosaturateit fulfills this requirement. Thisfact makeshigh-level series plate modulationexceptionally simple to adjust.It isn't necessary toconnect the modu-lating signal in series with the de powerinput as shown in Fig. 8. There's anotherwayofdoingit that gets by with a little lessinthewayof components, but is somewhatrestricted in other areas.This alternate way is actually an oldertechnique. Insteadof connecting themodu-latingacandthe power supply's dein series,we can connect theminparallel. We mustplace a choke in series with thede powersupplysothat it won't short the ac signal toground. Theresult lookslikeFig. 9, and thetechnique is known as "Heising" modula-tion.Flg. 9 . Parallel connection ofmodulator andmodulatedstage isalsopossible. The circuitisknown as " Haising" modulationandhasmany variants. It isespecially popular forlow-power equipment since it avoids needfor bulky modulation transformers and iscapable of excellent modulation quality.Disadvantage is that modualtor mustbe abletodissipatepowerequal tothat suppliedtorf stage.96 73 MAGAZINEAll Gear Unconditionally GuaranteedBO X3 7A PH ONE 6 0 588 6 5 749WATERTOWN. SO. DAKOTA 57201$299.00$139.00$449.00$ 49.00$ 89.00$199.00$199.00$109.00$269.00$ 79.00$ 49.00$ 79.00$ 89.00$ 89.00$199.00GETYOURNEWISSUENOW!Over 283. 000 QTHsin t heU.S. edit ion$7.95Over 135,000 QTHsin the ox edition$4.95 RadioAmilteurs 'Prefiusbr Countr ies! " .R.R.L. Phonetic Alphabet ! WhereToBur ! Great Circle Bur inl;S! International PostalInformation! Plus much more!t=.t:...>'-'S; see your f avori te dealer ororder direct (add2Se f ormaili nginU.S., Possessions& Canada. rt sewn er e add50e)." RADIOAMATEUR 116 kJsc a 00 INCDept . B. 925 SherwoodDrivel,ke Bluff. II I. 60044 QSL MiinaCersAroundtheWorld! Census of RadioAmateursthrouchoutthewor ld! RadioAmateurs' LicenseClass! World Pre'i.Map! International RadioAmateurPrefilUTheseva luabl e EXTRA f eaturesi ncludedin bot h edit ions!, enca'sMost Reliable ,AMATEUR DEALER SINCE 1937Now Featuring Drake and Swan EqUipmentplus a Full Line of Amateur Accessories.CURRENT USED GEAR LISTCollins 755 1 Revr. w/wts rjtn. tuningDrake 2A withmatching speakerDrake TR3 w/ACsupply &RV3remote vfoEico 762 DCmobile power supplvHallieralters HT30 SSB/AM/CW xmtr,Hallicrafters HT32 SSB/AM/CW xmtr,Hallieraltars HT37 SSB/AM/CW xmtr,Hallierafrers SR42 2 meter transceiverHammarlund HQ170A-VHFall bands160 thru2Heathkit TX-l Apache transmissionsHeathkit DX100 transmitter-asis-JohnsonViking RangerLafayette TR106 6 meter transceiverSwan 410 vlo (new) lor 350e/5000Swan TV2(14me. ifl2 mtr, xcvr,

to overmodulate.Some circuits used for screen modulation,incidentally, amount to the application oftheHeisingtechnique tojust the screenofthemodulatedstage. Anotableexampleisthat known as " clamp-t ube" modulation,which uses the Heising technique with aresistor rather than a choke.Cathodemodulation, whichis sometimesemployed, isacrossbetweengridandplatemodulation, becausein most amplifiersthecathodeiscommontoboth the grid and theplatecircuits. It shares most of the disadvan-tages of grid modulation and achieves few oftheadvantagesof plate modulation, andsohas not found its way into general use.Now that we've looked at the variouswayst oproduceAMby varyingtheampli-tude characteristicofthecarrier, let's tumour attention to FMand PM. Since theoutput signalsproducedbyFM andPMareso similar, we'll look at these types ofmodulation together.WeproduceFM by varying the frequencyofthecarrier, andPMbyvarying the phase.However it ' s not possible to change thefrequency of a signal without at the sametimechangingits phase, norcanwe changethephasewithout anaccompa