HP-404A-Manual-sn-462 电路图.pdf

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 1 INSTRUCTIONANDOPERATINGMANUAL FOR MODEL404A VACUUMTUBEVOLTMETER (PORTABLE) Serial462andAbove Copyright1954byHewlett-PackardCOtnpany Theinform.ationcontainedinthisbooklet isintendedfortheoperationandm.ain- tenanceofHewlett-Packardequipm.entand isnottobeusedotherwiseorreproduced withoutthewrittenconsentoftheHewlett- PackardCom.pany. HEWLETT-PACKARDCOMPANY 395PAGEMILLROAD,PALOALTO,CALIFORNIA,U.S.A. RadioFans.CN 收音机爱 好者资料库 GeneralDescription TheModel404AVacuumTubeVoltmeterisdesignedforgeneralvoltage measurementswherealternatingcurrentpowerisnotavailable.Itisaneasily handledportablevoltmeterusingself-containedstandarddrybatteries. Measurementsofvoltagesfrom.00Ito300voltsatfrequenciesfrom2 to20,000cycles/sec.mayQemadewiththisinstrument.Thesevoltageand frequencyrangesmakethisinstrumentsuitableforremotebroadcastlineand carriercurrentchecks,straingaugesystemtests,geophysicalandtelemetering circuitmeasurements.Itm.ayalsobeusedasastandardamplifierof60db gain. CAUTION THEMAIMUMVOLTAGEAPPLIEDTOTHEINPUTTERMINALSOFTHE MODEL404AVACUUMTUBEVOLTMETERMUSTNOTEXCEED600VOLTS THESUMOFTH,EDCVOLTAGEANDTHEACPEAKVOLTAGE.HIGHERVOL- TAGEsWILLBREAKDOWNTHECAPACITORINTHEINPUTSYSTEMOFTHE INSTRUMENT. CAUTION INORDERTOOBTAINMAXIMUMUSEFULLIFEFROMTHEBATTERIES INTHISINSTRUMENT,ALWAYSTURNOFFTHEPOWERSWITCHWHENTHE INSTRUMENTISNOTINUSE. PartsSubstitutions Difficultiesinprocuringsomeofthepartsusedinthisinstrumentmay causetheelectricalorphysicalvaluestodeviatefromthoseshowninthisin- structionmanual.Thesesubstitutionshavebeenmadesoasnottoimpairthe performanceofthisinstrument.Wheneverthereplacementofanyoftheseparts isnecessary,eitherthesubstitutevalueortheoriginalvaluemaybeused. RadioFans.CN 收音机爱 好者资料库 TABLEOFCONTENTS MODEL404A VACUUMTUBEVOLTMETER (PORTABLE) PageNo. Specifications. oooootJ...oo.,o1 OperatingInstructions Inspection . . ControlsandTerminals Operation CircuitDescription Maintenance BatteryReplacement TubeReplacement. _ CalibrationProcedure.. TroubleShooting TableofReplaceableParts 2 2 3 7 8 8 9 11 12 f INSTRUCTIONS MODEL404A VACUUMTUBEVOLTMETER (PORTABLE) Specifications VoltageRanges-- VoltsFullScale(RMS)- .003,.01,.03,.1,.3.1,3,10,30,100,and300 DB- -50,-40, -30, -20,-10,0,+10,+20, +30,+40,and+50 FrequencyRange-- 2to50.000cycles/second Accuracy-- 3%offullscale.2to20,000cycles/sec. 7%offullscale,2to50.000cycles/sec. Includingcalibrationerror,tubeaging,andbatteryaging. MeterCalibration-- MetercalibratedtoRMSvalueofasinewave. Linearvoltagescales0 -IVand0 -3V. DBscale--12to+2db Voltagerangesrelatedby10DBsteps. Zerolevel=1milliwattinto600ohms. Inputhnpedance-- 10megohmsshuntedbyapproximately20I-L..tf. Amplifier-- Maximumgain-60db5dbintoanopencircuit Maximumoutputvoltage-15voltsintoanopencircuit -1- PowerSource(SelfContained)-- Filament- 5BurgessNo.Z(orequivalent)flashlightbatteries(l-l/Zvolts each) Plate3Burgess#Z30NX(orequivalent)batteries(45voltseach) BatteryLife-60hourstotalwhenusedatarateof4hoursdaily. OverallDimensions lZ-1/8highx 9-7/8widex10-3/8deep Weight Approximately17lbs.includingbatteries OperatingInstructions Inspection-- Thisinstrumenthasbeenthoroughlytestedandinspectedbeforebeing shippedandisreadyforusewhenreceived. Aftertheinstrumentisunpacked,itshouldbecarefullyinspectedfor damagereceivedintransit.Ifanyshippingdamageisfound,followthepro- cedureoutlinedintheClairnforDamageinShipmentpageatthebackofthis instructionbook. .. ControlsandTerrninals BELOW10CPS-ABOVE10CPS-IntheBELOW10CPSswitchposition, additionalcapacityisconnectedacrossthemetertopreventthemeterpointer fromoscillatmgwhenmeasuringvoltagesatfrequenciesbelow10cycles/sec. ThisswitchdoesnotfunctionwhentheVOLTMETER-AMPLIFIERswitchisset toAMPLIFIER. OFFON-Thisrotaryswitchcontrolsthepowersuppliedtotheinstru- mentfromthebatteries.WhentheswitchisintheOFFposition,thefourfila- mentcircuitsandthetwohighvoltagewiresfromthebatteriesareopened.When theinstrumentisturnedon,theneonlamponthecontrolpanelwillflashperi- odically. VOLTMETER-AMPLIFIER-IntheVOLTMETERpositiontheinstru- mentfunctionsasavoltmeter.WhenthetoggleswitchischangedtotheAMPLI- FIERposition,themeterMlandthetwocrystalrectifiersareswitchedoutof thecircuitandtheinstrumentfunctionsasanamplifierwith60dbgain.This switchalsoconnectstheoutputoftheamplifiertotheOUTPUTterminalsand insertsthenecessarycompensatingresistorsintheamplifieroutputcircuit. -Z- Fig.IModel404AVacuumTubeVoltmeter INPUT-Thetwobindingposts,locatedinthelowerleftcornerofthe contropanelpareconnectedtotheinputcircuitoftheinstrument.Thelower bindingpostmarkedGisconnectedtothechassis. OUTPUT-Thetwobindingposts,locatedinthelowerrightcornerof thecontrolpanelparetheoutputterminalsoftheamplifier.Thelowerbinding postmarkedGisconnectedtothechassis. RMSVOLTS-DB-Thisrotaryswitchconnectsthepropermultiplier resistorsintothecircuitforthedesiredvoltagerange.Thepositionofthe switchindicatesthemeterscaleandfullscalevoltageoftherangeinuse.The switchpositionalsoindicatestheDBlevel(instrumentconnectedacross600 ohms)whenthemeterpointerindicateszeroontheDBscale. Operation-- CAUTION THEMAXIMUMVOLTAGEAPPLIEDTOTHEINPUTTERMINALSOFTHE MODEL404AVACUUMTUBEVOLTMETERMUSTNOTEXCEED600VOLTS, THESUMOFTHEDCVOLTAGEANDTHEACPEAKVOLTAGE.HIGHER VOLTAGESWILLBREAKDOWNTHECAPACITORINTHEINPUTSYSTEMOF THEINSTRUMENT. VoltageMeasurements-SettheDB-RMSVOLTSrangeswitchtothe desiredoltagerange.theVOLTMETER-AMPLIFIERswitchtoVOLTMETER and,e3LOW10CPS-ABOVE10CPSswitchtothecorrectpositionforthe frequencyofthevoltagetobemeasured.TurntheOFF-ONswitchtoONand connecttheINPUTterminalstothevoltagebeingmeasured.Themeterscale multiplyingfactor(DBRMSVOLTSswitchpositiondividedbythefullscale alueofthemeterscaleinusetimestheTIleterindicationequalsthevoltage beingmeasured. Examples: A.100(DB-RMSVOLTSswitchposition)-71(fullscalevalueofTIleter scaleinuse)=100(MeterscaleTIlultiplyingfactor) -3- 100(Meterscalemultiplyingfactor)x.83(meterscaleindication)=83 volts(measuredvoltage) B.30(DB-RMSVOLTSswitchposition)..;- 3(fullscalevalueofmeter scaleinuse)=10(meterscalemultiplyingfactor) 10(meterscalemultiplyingfactor)x2.3(meterscaleindication)=23 volts(measuredvoltage) Asaprecautioninmaintainingaccuracyofmeasurement,itmustbekept inmindthattheinstrumentisanaverage-readingdevice.Althoughthecalibra- tiononthefaceoftheinstrUlnentismarkedRMSVOLTS,thissimplymeans thatthemeterwillreadthermsvalueofatruesinewave.Ifthewaveformof thevoltagebeingmeasuredcontainsappreciableharmonicvoltagesorother spuriousvoltages,errorsinmeasurementwillbeencounteredofamagnitude indicatedbythefollowingtable. %TrueRMSMode1404APeakMeter HarmonicValueIndicationIndication 0100100100 10%2nd100.510090to100 20%2nd102100-10280to120 50%2nd112100-11075to150 10%3rd100.596-10490to110 20%3rd10294-10880to120 50%3rd11290-116108to150 DBMeasurement-Decibelmeasurementsaremadeinthesamewayas voltagemeasurelTIentsexceptthattheDBscaleisusedandthelTIeasurements mustbelTIadeacross600ohlTIs,ifthe1milliwattacross600ohmsreference levelistobeused.Thedifferencebetweentwoormorevoltages,measuredin decibels,maybereaddirectlyfromtheModel404Aprovidedeachmeasurement ismadeacrossthesamevalueofimpedance.Thedecibellevelbeingmeasured isdeterminedbysumordifferenceofthemeterscaleindicationandtherange switchindication.Theplusorminussignsbeforethemeterscalefigures,de- terminewhetherthemeterscaleindicationistobeaddedorsubtractedfromthe decibellevelshownbytherangeswitch. -4- 4) o ..c Examples: C.Interpretingtherangeswitchpositionandmeterscaleindicationfor aleveloft12db.Measuredacross600ohmswithonemilliwattacross600ohms asthereferencelevel. t10db(DB-RMSVOLTSswitchposition)plust2db(dbmeterscaleindi- cation)=t12dbor t20db(DB-RMSVOLTSswitchposition)plus-8db(dbmeterscaleindi- cation)=t 12db D.Interpretingtherangeswitchpositionandmeterscaleindication.for thedifferencebetweentwovoltages$measuredindecibels,acrossthesame valueofimpedance. Voltagesequal-37dbandt12db. -30db(DB-RMSVOLTSswitchposition)plus- 7db (dbmeterscaleindication)=-37db tlOdbplust2db(fromExampleC)=(-)t12db 49db(totaldecibeldifference betweenthetwovoltages) AnoscilloscopemaybeconnectedtotheOUTPUTterminalsoftheinstru- mentforobservingthewaveshapeofthevoltagebeingmeasured. ZeroMeterIndication-Themeterpointermaynotcoincidewiththezero scalemarkhentheinstrumentisturnedoff.Thisconditionisnormal. Thezeroadjustmentscrewissetforoptimummetertrackingaccuracy andthenthescrewissealed AmplifierOperation-Tochangetheinstrumenttooperateasanampli- fierpsettheVOLTMETER-AMPLIFIERswitchtoAMPLIFIER.Connectthe INPUTterminalstothevoltagetobeamplifiedandtheOUTPUTterminalstoa highimpedanceload(100,000ohmsormore)suchasanoscilloscope.Setthe RMS-DB(rangeswitch)sothattheinputvoltagedoesnotexceedthevaluesgiven inthefolIoingtable. RangeSithMaximumOverall PositionInputGain .003V.015V60db .01V.045V50db .03V 15V40db . 1V.45V30db .3V1.5V20db 1.0V4.5V10db 3.0V15.0Vodb -5- Themaximumgainobtainablefromthisamplifieris60db,overthefre- quencyrange2to20,000cycles/sec.,whentherangeswitchisinthe.003volt position.Themaximumoutputvoltageobtainablewithnegligibledistortionis 15voltsintoanopencircuitattherangeswitchpositions.003.01,I,.3.3 volts.Theoutputvoltageatthe.03and1voltrangeswitchpositionsislimited to7volts.Rangeswitchpositionsabovethe3voltrangeprovidelessthanunity amplifiergain. -6- .. CircuitDescription TheModel404AVacuumTubeVoltmeterconsistsoffrequencycompen- satedattenuator,amplifier,meterrectifiercircuit,anddrybatteriestosupply thefiamentandplatevoltages. Theunknownvoltageisa.ppliedtotheinputterminalsoftheinstrument whichareconnectedthroughCltothefirstsectionofthefrequencycompensated attenuaor.ThissectionoftheattenuatorconsistsofC2-CS,Rl-R6,andSlA- 5C,51H.Themannerinwhichthevariouselementsoftheattenuatorarecon- nectedforeachvoltagerangeisshowninFig.2. Aftertheunknownvoltagehasbeenattenuatedsufficientyitisappiedto thegridoftubeVI.TubesVIandV2formatwostageresistancecoupledampli- fierwhichisstabilizedbynegativefeedback.Theoutputofthisamplifierisfed tothesecondsectionofthefrequencycompensatedatenuatorthroughcapacitor C10. Theamplifiedunknownvoltageisreducedinthissectionoftheattenuator inthesamewayasinhefirstsectionbutinadifferentamount.Thesecond sectionconsistsof Cll-C14,R16-R20,51D,51G,5lI,5lJ.Theconnectionsof t evariouselementsoftheattenuatorforeachvoltagerangeareshownbelow. TubesV3andV4areconnectedasatwostageamplifierwithnegative feedback.Thisampifieramplifiestheunknownvotagefromthesecondsecion oftheattenuatorandfeedsittothemeterrectifiercircui.Thetwocrystal rectifiersCR1andCR2providefull-waverectificationoftheunknownvoltage andproduceadirectcurrentwhichcausesthemetertoindicatetheRMSvalue oftheoriginalnknownvoltage.Themetercircuitisreturnedtogroundthrough resistorsR30, R31.Votagefromthiscircuitisalsoappiedtothegridcircuit ofV3toprovidenegativefeedbackaroundtubesV3andV4. Whenheinsrumentisusedasanampifier,themeerrectifiercircui iremovedfromthecircuiandcompensatingresistorsareinseredtomain- tair.thecorrectnegativefeedback. -7- Maintenance BatteryReplacement-- MeasurementofBatteryVoltage-Themostconvenientmethodofmeas- uringthebatteryvoltageistounscrewtheclearplasticcoverandremovethe neonglowlampIl.Connectthenegativeterminalofahighresistancevoltmeter tothechassis.Turnontheinstrumentandconnectthepositiveterminalofthe voltmetertotheshellorcentercontact(thecontactproducingthehighestvolt- meterindication)oftheneonlampsocket.Forsatisfactoryoperationofthein- strumentthisvoltageshouldbe100volts(fllamentvoltage1.1volts)ormore withtheinstrumentinoperation. Whenthebatteryvoltagedropsbelow100volts,boththefilamentand platesupplybatteriesmustbereplaced.Ifthebatteriesareusedafterthevolt- agehasfallenbelow100voltsinaccuratevoltagemeasurementswillresult. Theinstrumentisdesignedsothattheplateandfilamentbatterieswill deteriorateatapproximatelythesamerate.Therefore,thetwosetsofbatteries mustbereplacedatthesametime. BatteryReplacementProcedure-Theprocedureforreplacingthebat- teriesisasfollows: 1.Removethecasecoverandunscrewthetwocaptivescrews.Slide theInstrumentoutofthecase. Z.Facethebackoftheinstrument.Removethefourscrewswhichhold thebackplateinplaceandremove.Loosenthebatteryterminalsandremove allthewiresfromthebatteries. 3.Liftoutthebatteriesandreplacewithasetoffreshbatteries.Con- nectthewirestotheproperterminals.(SeeFig.)Replacethebackplate. 4.Replacethefilamentsupplybatterieswithfreshbatteries. 5.Turnontheinstrumentandmeasurethebatteryvoltagesasdescribed intheMeasurementofBateryVoltagesection.Theplatebatteriesshouldbe atleast130voltsunderloadandfilamentbatteriesatleastl-l/Zvoltswhen loaded.Ifthebatteryvoltagesarenormal,thenreplacetheinstrumentinthe case. TubeReplacement Ifthetubesusedforreplacementinthisinstrumenthaveaveragecharac- teristics.therewillbelittleornochangeinthecalibration.However,ifthere isreasontosuspectthecalibrationaccuracy.theinstrumentshouldbechecked againstaknownsinewavevoltageorcomparedwithanothermeterthatisknown tobeaccurate.Theproceduresdescribedbelowmaybeusedtorestorethecali- brationtoapproximatelyItsspecifiedaccuracyortheinstrumentmaybereturned -8- - Fig.2 N totheHewlett-PackardCo.wherethisservicewillbeperformedforanominal charge. CalibrationProcedure ScreenVoltageAdjustment-ThisadjustmentisnecessarywhentubeVI orV2hasbeenreplaced.WhenthescreenresIstorR9hasbeensettotheopti- mumva.lue.theaccuracyoftheinstrumentispracticallyindependentofthede- creaseinvotageoftheplatesupplybatteriesoverthenormallifeofthebatteries. Theprocedureforthisadjustmentisasfollows: LRemovetheinstrumentfromthecaseandremovethebackplateso thatthebatteryconnectionsareaccessible. 2.OperatetheinstrumentasavoltmeterandapplyavoltageofIvolt RMSat100cycles/sec.totheINPUTterminals.Recordtheexactmeterindi- cation. 3.TurnofftheInstrument.Re-connectthehighvoltagewirestothe batteriesBT6.BT7,BT8)asfollows:SeeFig. +135V(redire)tothe112-1/2V.batteryterminal +112-1/2(orangewire)tothe+90V.batteryterminal +135Vbatteryterminalvaca.nt 4.Turnontheinstrument.Applyexactlythesamevoltage,asinstep 2.totheINPUTterminals.Ifthemeterindicationisthesameasbefore.no adjustmentisnecessary. 5.Iftheadjustmentiscorrect.thenreturnthebatterywirestotheir origmalterminals. 6.Ifadjustmentisnecessary.adjustR9(seeFig.3sothatthemeter Indicationisthesameaswasrecordedforstep2.Inputvoltagesameasinstep2. 7.Returnbatterywirestotheiroriginalterminals.Repeatstep2.If heoriginalmeterindicationandthemeterindIcationobtainedinthisstepare thesame,theadjustmentiscomplete.Ifthemeterindicationsarenotthesame. repeataltheaboveadjustments.Anothernewtubemaybenecessaryifthecor- rectadjustmentcannotbeobtaineda.fterseveraltries. CalibrationAdjustment- -Adjustmentofthe.003voltrangemaybeper- formedinthefieldandusuallythisadjustmentwillprovidesatisfactorycalibra- tionacuracy.Theadjustmentofthefrequencyresponseandothervoltageranges shouldnotbeattemptedinthefield. Theproedureforadjustingthecalibrationofthe.003voltrangeisas follows: 1.Settherangesitchto0