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1、 HP Archive This vintage Hewlett Packard document was preserved and distributed by www. Please visit us on the web ! On-line curator: Glenn Robb This document is for FREE distribution only! RadioFans.CN 收音机爱 好者资料库 INSTRUCTIONS LOWFREQUENCYSTANDARD MODELIOOA GENERALDESCRIPTION The Model100ALowFrequen
2、cyStandardconsistsofa 100 kccrystal-controlledoscillator,and aseriesofthree10 to1regenerativemodulatortypefrequencydividersproviding frequenciesof10kc,1kc,and 100cps.Output fromeachfre- quencyisbroughttoseparateterminalsattherearofthechassis throughbufferstageshavinga lowoutputimpedance.Twooutput te
3、rminalsarealsoprovidedonthefrontpanel,togetherwitha switchtoselectanyoneoftheoutputfrequenciesdesired.Out- putonallfrequenciesisessentiallysinusoidal. 100 kcOscillator:The 100 kcoscillatorconsistsof a 100 kccrystalhavingatemperaturecoefficientof2cyclesper megacycleperdegreeCentigrade,inamodifiedColp
4、ittscircuit usinga 6SJ7oscillatortube.Thecrystalisinserieswiththe tankinductance,thecircuitoscillatingundercontrolofthe crystalwhenthetankcircuitistunedapproximatelytothecrys- talfrequency.Oscillationswillbemaintainedoverafairrange ofthetuningcapacitor,whichisusedtoadjustthecrystalto exactly100kc. F
5、requencyDividers:Thefrequencyofthe100 kcoscil- latorisdividedinstepsof10to1,bymeansofthreeregener- ativemodulatortypefrequencydividers.Thefirstdividersteps the100kcdownto10kc,theseconddividerstepsthe10lecdown to1kc,andthethirdstepsthe1 kcdownto100cps.Theaction ofallthreedividersisalike,althoughtheex
6、actmethodofob- tainingtheresultdiffersslightlyineach.Thefundamental actionisasfollows: Afrequencyfisintroducedintothefirstgridofa 6L7modulator.tube whichhasitsplatecircuittunedtoafre- quencyf/lO.Theplatecircuitisalsocoupledtooneofthe gridsofanother6L7actingasafrequencymultiplier,andhaving itsplateci
7、rcuittunedtoafrequency9f/lO.Theplatecircuit ofthemultiplierisinturncoupledbacktothethirdgridof themodulatortube. Assume atransientofsomesorthasstartedasmall voltageofafrequencyfllOintheplatecircuitofthemodula- tor.ThisismultipliedbythemultiPLiertubetoafrequency 9f/lO,andfedtothethirdgridofthemodulat
8、orwhereitmixes withthefrequencyfcominginonthefirstgridtogive-afre- quencyf-/10,orfllO,inthemodulatorplatecircuit,in- creasingthef/IOvoltagestartedoutbytheinitialtransient. 1 RadioFans.CN 收音机爱 好者资料库 Theactiongoes aroundthecircuitagain,thefilO voltagesoonbuildinguptoastablemaximumvalue.Ifthein- coming
9、frequencyfisremoved,thefilOvoltagewillimmediately stop,forthereisnothingtomixwithtomaintainitselfin operation. Inordertofacilitatethemultiplyingactionincertain cases,someofthefrequency!isintroducedinoneoftheother grids-ofthemultipliertubewhere amodulatingactionthentakes place,similartothatinthemodul
10、atortUbe,thefrequency-fcom- biningwiththefrequencyfllOtogiveafrequencyf -fllO,or 9f/lO,initsplutecircuit. BufferStages:Output fromthe100 kcoscillator,and eachofthedividersistakenfromseparatebufferstagesconsist- ingof6AC7striodeconnected,inacathodeloadcircuit.This providesa lowoutputimpedance,sothatl
11、oadsaslowas1000 ohns maybeplacedacrosstheoutputwithoutappreciablyloweringthe outputvoltage.Thecathodeloadcircuitalsoprovidescomplete isolationofthedifferentoutputfrequencies. PowerSupply:The powersourceshouldbe a 115volt, 60cyclesupplyline.Thehighvoltageisobtainedfromanelec- tronically-regulatedrect
12、ifiersupplysothatthelinevoltage mayvaryfrom 105to125voltswithoutaffectingtheoperation. Regulatingthehighvoltagesupplyalsoprovidesa low aUdioim- pedanceintheplatesupplycircuit,andaidsinpreventinginter- actionbetweenthevariousoutputfrequencies. OPERATION InitialInstallation:Whentheinstrumentisfirst pu
13、tintooperation,thefollowingprocedureshouldbeobserved: 1.MakesurealltUbesarefirmlyintheirsockets, andthatthegridclipsareonallthe6L7tubes. 2.Plugpowercordintoa 115volt,60cyclepower supply.Itwilltakeabout24hoursofheating forthecrystalitselftocomeuptotheproper operatingtemperature.Attheendofthattime, ch
14、ecxtheratiosbetweenthevariousfrequency dividerswithanoscilloscope,asfollows: g.Conneetthehorizontaldeflectingplatesto the10 kcbindingposts,andtheverticaldeflectingplatesto the100 kcbindingposts.Astationarypatternwith10peaks acrossthetopshouldbeobtained.Ifthispatternisnotsta- tionary,orisblurred,adju
15、stthetuningcapacitorinthe10kc divideruntilaclear,stationary10to1patternisobtained. Thecapacitorshouldbeleftinthecentralpositionbetweenthe twopointswherethepatternceasestobestationary.Each dividercircuitisdirectlyinline,fronttorear,withits correspondingoutputterminalsattherearofthechassis. 2 RadioFan
16、s.CN 收音机爱 好者资料库 .Repeattheaboveprocedure,usingthe10 kc andthe1kcoutput,andthetuningcapacitoronthe1kcdivider. .Repeat,usingthe1kc and100cpsoutput,and thetap-switchcapacitoradjustmentforthe100cpsdivider. Outputvoltagesfromallfrequenciesshouldbe5volts orbetteron opencircuitafteraboveadjustments.Theinst
17、ru- mentisnowreadyforoperation. Outputfrom anyoftheoutputfrequenciesmaybeobtained separatelyfromthemarkedbindingpostsattherearofthechassis, orifdesired,anyofthefrequenciesmaybeobtainedfromthebind- ingpostsonthefrontpanelbysettingtheselectorswitchtothe desiredfrequency.Outputatallfrequenciesispractic
18、allysinusoi- dal,sothatfrequenciesmaybeusedforfrequencydeterminationby meansofLissajousfiguresuptoquitehighand complexratios. Leadingtheoutputwithlessthan1000ohmsloadwill lowertheoutputvoltageconsiderably,andwillalsocausesome distortionwhichmightbeobjectionableforusewithhighmultiple orcomplexpattern
19、s.Ifharmonicsoftheoutputaredesired,see page4forcompleteinstructions. Adjustmentof100lecOscillatorFrequency:Thefre- quencyofthe100kcoscillatorhasbeensetatthefactoryto withinacycleortwoof100kcattheexistingroomtemperature. Avariationof330Cwillcauseonlya0.0066%changeinfre- quency. MAINTENANCE Afterthein
20、itialadjustmentshavebeenmade, nofur- theradjustmentshouldberequired,exceptforoccasionalblowing outoftheunit,and acheckontheconditionofthetubes. Thefanshouldbecleanedandoiledeverythirtydays. Onecheckitiswelltomakeperiodicallyisthatof thefrequencyratioofthedividers,asexplainedintheoperat- ingsection,u
21、nderinitialadjustments.Thosedividersshould remaininoperationindefinitelywithoutchange,butextreme temperaturechangesoragingofthetUbes,etc.,maycausethem tobecomede-tuned,and beofffrequency,sothatanoccasional checkisasafetyprecaution. 111lERCIRCUIT foruse withthe -hp- 1oo-Aorloo-BLowFrequency Standard.
22、 Willsupply10kcharmonics upto20me UnknownSignal 1= Variable Coupling C5 50PIJ/ lC 8 Rlo-OK T r z 1 a: :6 lCC1 l:0 l:l: 0.n .001/ 0 a.X/ l1)I 0 0 0 I. t dJ ./ 11 Qr-GT . 4,- .-_.;- . o., ,2 - . :; 1 . . . , ,. . ., H , . ., u , ., - , , ., ., v-;. ._.- ., . .J.-:!,a A,h,c:!c-_:. -. ,. .-. .1l.3. .g.:.-.,=- - . - , - . , V-Ii:!. ., - . - . 0 . ;. V9 L v-6 h ,. -. . r.:ct f-.-. -. ,