HP-411A-Manual-sn-131 电路图.pdf

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1、 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 011931 OPERATINGANDSERVICEMANUAL MODEL411A SERIALSPREFIXED:131- RFMILLIVOLTMETER (u.IHWLIII.A(IO(O.N.J ISOAv._OAO.,0AllOCUIONliS Printed:FEB1962 RadioFans.CN 收音机爱 好者资料库 Iodel-111; TAauOfCONTENTS TableofComent! ListsofIllustrationsandTables 1 SCctionPa

2、geSectionPage I GElERALINFORMinoI-IIVPHINCIPI.ESOFOl-ERATIO:(Comdl 1-J.Gener,IIDescription I - I4-16.CathodeFollower, -2 1-3.ProbeTip.:Avail3bleI-I420.1.1oduialOTand 100keO,.,cillator-2 1-6.InstrumentIJentification1-14-22.PowerAmplifier-2 8.PowerC.lble1-14-25.Feedback-2 PREPAH/TIONFORl:SE2-1 VMAlTEN

3、ANCE51 . 5-I.Introduction5-1 21.Unpackingor230Volt,:;2-1 5-16.Troubleshooting5-2 213.Hack-Mountr-.lcx1el2- 2-15.PreparationrOlStorageandShipment2- 519.MeasurePowerSupplyVoltages5-2 .5-21.ileasurcRipple;-3 2-18.StorClge2-1 5-24.DownscaleMeterCircuit ;-3 5-26.ModulatOrIfmIlifierTuning5;, Ol-F.:RATION

4、.3- , 5-30.Ihx:lulalOl/AmpllfierCHin55 3-I.PreliminaryConsiderations3- ,:;31.UpscaleIeterClrluit55 3-5.ProbeTips3-15-33.OutpUlCircuit55 3-17.SelectionofProbeTtp3-25-3.j.BiasAdjustment5-5 3-19.InstallationofProbeTips3-25-35.HumBalanct:!5-5 3-22.rvlechanic.l1t.lctcr-Zelo3-25-36.ZeroC.ontroJ5-5 3-2-1.Z

5、eroAdjuslmcl1t3-25-37.ChopperAmplifierGain5-5 3-27.InterpretingReading3-25-10.MaintenanceProcedures5-5 5-41.Tran;!stororTubeReplacement55 V PRINCIILESUFOPERATfO:H 5-43.Calibration5-5 4-1.Introduction4-, 545.FinalTest5-7 ) -1-7.Probe4-2 4-10.r-.lodulator. .4-2VIlEPI.ACEAUI.EPARTS6-, -I. I2.ChopperAmp

6、lifier-26-1.Introduction. 6- 4-14.Dcmoduldtor.-204.OrderingInformation 6- LISTOfILLUSTRATIONS 3-9. 3-10. 4-1. 5-1. 5-2. 5-3. 5-1. S-.i. 5-6. 57. NllIlbcrTitle 1-1.Model-IlIAHfMillivoltmeter 3-1.FrequencyResponseofliNeOpen Cln.;uilProbeTip. 2.InputImpedanceof81COpen CilTuitProbeTip. 3-3.FrequencyResp

7、onseofTyreN .TProbeTip. 3-4.FrCQuencyResponseofPenType ProbeTip.,. InputImpedanceofPen-IypcProbeTip. -requel1l-y Respon,.,cofViiiProbeTip Input lmped,nceofVIW P!ObcTip. Page 1-1 3-0 -o 3-0 -o 3-0 3-0 3-1 lumbcrTille 3-1l.!rcquency Respon:;eof CapacitiveDivider ElectricalZero.I,djustmel1l OpcnHinp.:P

8、rocedure. BlockDiagram . . . . . . ServicingEchedCircuitBoards C.llibrationTeslSetup RightSideInlernalView TestSetupforrinalTest LeftSideInternalView PowerSupply(SchematicDiagram) Voltmeter(SchematicDiagram) Page 3-1 3,1 3- H 5-1 5-6 56 5-7 5-8 510 5-1I OJI(3-1 LIST0TAaLIS NumbtorTitle I-I.Specific.

9、ltlons. 5-1.RecommendedTc,.,tEquipment 5-2.ComponcntReplacement 6-1.Hcfe1OnccDcignatiollIndex 6-2.lepl,KelbleParts Page 1-0 5- .)2 6-2 6-R Iii Section I TableI-I TableI-I.Specifications Model 411A 1-0 VOLTAGE RANGE: 10mvrmsfullscaleto10voltsrmsfullscale insevenranges.Fullscalereadings of0.01, 0.03,

10、0.3,I,3, and 10voltsrms. FREQUENCY RANGE: 500kcto1gcwithaccessoryprobe tips. ACCURACY: 500 kcto 50mc,3%of fullscale;50mcto 150mc,6%of fullscale;150mctoI gc, 1 db using appropriate probe tips. METER SCALES: Twolinearvoltagescales,0to1and0 to 3, calibrated in thermsvalue of asinewave. DBscale,calibrat

11、edfrom+3to-12db; 0 db= 1mwin50 ohms. PROBETIPFURNISHED: 411A- 21EBNCOpenCircuitProbeTip,500 kc to500mc.Shuntcapacity:Lessthan 4pC Maximum input:200 vdc.Inputresistanceat 10 mc:typicalIy 80Kohms. INPUT RESISTACEo Dependsonprobe tip, frequency and input voltage typically200KohmsatImcand Ivoltrms. ACCE

12、SSORIESAVAILABLE: ProbeTips: 411A-2IBPenTypeProbeTip,500 kcto 50mc.Shuntcapacity:Lessthan 4 pf. Maximum input:200 vdc.Inputresistanceat 10 mc:typically80Kohms. 411A-21C VHFProbeTip,500 kcto250mc. Shuntcapacity:Lessthan2-1/2pCMaximum input:200 vdc.Inputresistanceat 10 mc: typically80Kohms. 411A-31DTy

13、peTeeProbeTip,Imcto Igc.SWRislessthanLISwhenterminated in50 ohms.Maximuminput:10vdc. 411A-21FlOO:ICapacityDividerProbeTip, 500kcto250mc.Division Accuracy:1%; shunt capacity:2 pf.Maximum input:1000 voltspk (dc+pkac). PROBE KIT: 411A-2IGAccessoryProbeKit.Thiskitin- cludesthe4I1A-2IB,411A-21C, 411A-21D

14、, 411A-21FProbeTipsand a41IA-2IA-3 ReplacementDiodeCartridge. TERMINATION: .10-+-+-1 10K1-+-7 rli?411A-11EBNCOPENCIRCUITPROBETIP .SHUNTCAPACITANCE5pf lOOK TYPICAL SHUNTIKI-+.-:b- RESISTANCE0.01vRANGE IOHNS)IDO1-_+-_-+-_ 1Of-+-+-+-.:.:=-j +I1-_4-_-,-1+-_-1 IOVRANGE TYPICAL RELATIVE0 RESPONSE lOB)-IF-

15、t-t-t-j 411A-1IEBNCOPENCIRCUITPROBETIP +21-_+_-1+-_-1 0.01 V RANGE -3_l-_+-_l_-l 100KCIMC10MCIDOMC1000MC .-$_,UIfREQUENCYG - S _71 II:-:-l-_l,.-,-+-,-,- 100KCIMC10MCIDOMC1000MC fREOUENCY Figure3-LFrequencyResponseof BNC OpenCircuitProbeTip Figure3-2.Input Impedance of BNC OpenCircuitProbeTIp -2ff-+-

16、t-t-j G-S-Il IDOMC1000MC IIA-1IBPEN-TYPEPROBETIP +3 +2 +1 TYPICAL RELATIVE 0 RESPONSE lOBI -I -2 -3 100KCIMClOMe fREQUENCY O.OIVRANGE +II-:I:-:-:-:=:+-+-:;j IOVRANGE - 31-_-+.-_-+-_-1-_- 100KCIMC10MCIDOMC1000MC fREOUENCY t!ii411A-11DTYPENTCQNNECTOR +3,-,-r-,-, +21-+-+-+-1 TYPICAL RELATlVE0 RESPONSE

17、lOBI-I Figure3-3.FrequencyResponseof TypeNTProbeTip Figure3-4.FrequencyResponseof Pen-TypeProbeTip 5-5-.14 + I1-+-.,1-+-+-1 IOVRANGE rli?IIA-11CVHfPROBETIP +3,.-,-r-,-, O.OIVRANGE -2I-t-+-+-.I.i -31-_-1-_+-_+-_-1 100KCIMC10MCIDOMC1000MC +21-+-.,1-+-1 fREQUENCY TYPICAL RELATIVE0 RESPONSE lOB)- IP-II-

18、j-t-= I MEG r!iJ411A-11BPEN-TYPEPROBETIP SHUNTCAPACITANCE4pf OfcO=-KCC,-1IMCC-1IOCM-C-+IOCO-MCC-,OOOMC fREQUENCY 101-+-+-+-_1 lOOK 10KI-+-:7-+-,.=-_1 TYPICAL10VRANGE SHUNTIKI-+-;+-+-_1 RESISTANCE0.01vRANGE (OHMS)1001-_+-_-+-_-+_-j Figure3-5.Input Impedance of Pen-TypeProbeTip Figure3-6.FrequencyResp

19、onseof VHFProbeTip 3-001193-1 Model41lASectionIII Paragraphs3-1to3-15 SECTIONIII OPERATION 3-1.PRELIMINARYCONSIDERATIONS. 3-2.Forthe majority of youruses(measuringcomin- uoussinewaves) theModel 411A willindicatethe root-meao-squarevalue directly.Whenmeasuring unusual waveforms, a correction factor m

20、aybenec- essary.Seeparagraph3-27,InterpretingtheRead- ing,forfurtherdetails. 3-7.BNCOPENCIRCUITPROBETIP.Hewlett- Packardstocknumber411A-21 E.Frequencyrange 500 kcto500mc.Maximumvoltage200voltsdcor 30 volts peakac.Typicalfrequencyresponsewith voltage and frequencyisasshowninfigure3-L. 3-8.Typicalinpu

21、tresistancevarieswith voltage and frequencyasshowninfigure3-2. CAUTION BE SURE TO GROUND THIS INSTRUMENT BEFOREUSE. 3-3.Goodrf measurements require proper ground- ing.TheModel 411Acontainsalinefiltertoelim- inatestrayrffromthe power line.Therefore, you must ground the instrumentchassisproperly to ma

22、kesignificantmeasurements.Inaddition,the filterconfigurationissuch thatifyoudonotground the instrument,itschassisassumesavoltageof about one-half the line voltage.andyoucan damage circuitsundertest. 3-4.Togroundyourinstrumentproperlyusea NEMA receptaclewith a third-prong ground.If,however, youusethe

23、 two-prong power adaptorbesureto groundthethirdwirepigtail. 3-9.TYPETPROBETIP.Hewlett-Packard stocknumber411A-21D.FrequencyrangeImcto 1000mc.SWRislessthan 1.15 whenterminatedin 50ohms.Maximum input 10voltsdc and 30 volts ac.Typicalfrequencyresponsewith voltage and frequencyisasshowninfigure3-3. 3-10

24、.SWRislessthanLISwhenterminatedin 50 ohms.Insertionlossislessthan Idb(lessthan 0.1 db uptoISOmc). 3-11.PEN-TYPEPROBE TIP.Hewlett-Packardstock number411A-2IB.Frequencyrange500kcto50mc. Maximuminput 200 volts dc and 30 volts peakac. Typicalfrequencyresponsewith voltage andfrequency isasshowninfigure3-

25、4. 3-12.Typicalinputresistancevarieswith voltage andfrequencyasshowninfigure3-5. 3-S.PROlETIPS. 3-6.FiveprobetipsareavailablefortheModel411A. TheseprobetipsenableyoutousetheModel 411A foralmostany measuring application.Datatoguide you intheselectionoftheproperprobetipfollows (shadedareasindicateposs

26、iblevariations dueto temperature).Ifyou wishtomake yourownprobe tip thenecessarydataisalsogiven.The following probe tipsareavailable: 3-13.VHFPROBETIP.Hewlett-Packardstock number411A-21C.Frequencyrange500kcto250mc. Maximuminput 200 voltsdcand 30 volts peakac. Typical frequencyresponsewith voltageand

27、 frequency isasshowninfigure3-6. 3-14.Typicalinputresistancevarieswith voltage andfrequencyasshown infigure3-7. 3-15.CAPACITIVE D1VlDER(I00:I).Hewlett-Packard stocknumber411A-2IF.Frequencyrange500kcto IMEG lOOK -$-lU o -I +II-.,L-+-_+-_ +2I-+-+-l -2-:+:-+-+-1 -31-_-.4-_4.-_-1-_-1 100KCIMC10MCIOOMC10

28、00MC fREOUENC! TTPICAl RElATIVE RESPONSE (OBI I!i!411A-21fCAPACITIVEDIVIDERPROBETIP +3,.-r-,-,-, 10KI-+-;f- 10f-f-I-I-l 4I1A-ZICVHfPROBETIP SHUNTCAPACITANCE22pI I1:-:-.,-+-:-+-1-1 IOOKCIMC10MC100MC1000MC fREOUENC! TTPICAl INPUTIKf-c-c+-:-:.f-t- RESISTANCEO.OIVRANGE (OHMSI100I-_+-_+_+_ Figure3-7.Inpu

29、t Impedance of VHFProbeTip Figure3-8.FrequencyResponseof Capacitive Divider 01193-13-1 SectionIII Paragraphs3-16to3-29 250mc.Maximuminput 1000voltspeak(dc+peak ac).Shuntcapacity2 pf.Divisionaccuracy1%. TypicalfrequencyresponsewimvOltage andfrequency isshown infigure3-8. 3-16.MAKING PROBETIPS.Forspec

30、ialapplica- tionswherenOneoftheseprobetipsaresuitableyou maymakeyourownprobetip.Thesignalmustbe coupledthroughablockingcapacitortothecenter conductor(renninal)ofthediodecartridge.The ground-returnpathshouldgototheDurerconductor ofthecartridge.Theblockingcapacitorusedshould be130 pf1%.r$jJstockno. 01

31、50-0067. highleakage resistancetype(mylar),andhavea high enoughvolt- ageratingtoblockanyde.Thisblockingcapacitor isnecessaryfortheoperationofthemillivoltmeter andshouldbe used evenifthesignalsourcehasno decomponent. 3-17.SELECTIONOFPROBETIP. 3-18.Inchoosingtheproperprobetip.besidesthe obviousselecti

32、onofcoaxialornon-coaxialtypes, otherpropertiesof theprobesmustbeconsidered. Forinstance,at25meeitherthepen-typetiporthe vhftipmaybeused.However,thevhfhaslessshunt capacityandthereforeshouldbeusedinhighimped- anceapplications,orwheretheleastdisturbanceto thecircuitisdesired.Inasimilarmannerallthe spe

33、cificationsfortheprobetipsshouldbeconsidered whenselectingthebestonefortheapplication. 3-19.INSTALLATIONOFPROBETIPS. 3-20.Aftertheproperprobetiphasbeenselected. installiton theprobebody bylooseningthelocking collarandunscrewingthepresentproberip.ifany, andscrewingthenewprobetipinitsplace.Screw thene

34、wprobetipdownuntilitjustbonoms. CAUTION Excessivetorquewilldestroythecartridge. 3-21.Screwthecollaruptolocktheprobetipin place.Keepthediodecartridgewhich fitsintothe probetipclean.Donot touchthecartridgewhen installingthenewprobetip.Runthelockingcollar tightlyagainsttherearoftheprobetip(besurethe pr

35、obetipdoesnotrotatewhilethelockingcollaris beingtightened). 3-22.MECHANICALMETER-ZERO. 3-23.Whenmeterisproperlyzeroset,pointerrests overthezerocalibrationmarkonthemeterscale wheninstrumentis1)atnormaloperatingtemper- ature,2) initsnormaloperatingposition,and 3) turnedoff.Zero-setasfollowstoobtainbes

36、taccur- acyandmechanicalstability: 3-2 Mode1411A a. Allowtheinstrumenttooperateforatleast20 minutes;thisallowsmetermovementtoreachnormal operatingtemperature. b.Turninstrumentoff and allow 30secondsfor allcapacitorstodischarge. c.RotatemechanicaIzero-adjustmentscrewclock- wiseuntilmeterJXinteristole

37、ftofzeroand moving upscaletowardzero. d.Continuetorotateadjustmentscrewclockwise; stopwhenpointerisrightonzero.Ifpointerover- shootszero,repeatstepsc andd. e.Whenpointerisexactlyonzero,rotateadjust- mentscrewapproximatelyISdegreescounterclock- wise.Thisisenoughtofreeadjustmentscrewfrom themetersuspe

38、nsion.If.pointermovesduringthis stepyoumustrepeatstepscthroughe. 3-24.ZEROADJUSTMENT. 3-25.ProcedureforadjustingtheZEROcontrolis giveninfigure3-9.Asthiscontrolisturnedcounter- clockwiseithascontroluntilthemeterreacheszero. Whenthemeterreadsbelowzero.theactionofthe ZEROcontrolissluggish.However.theze

39、rodoes notalwayshavetobesetaccurately.Aslighterror inzero-settingbecomeslessimportant(atasquare- lawrate)astheinputvoltageisincreased.For example,ifthezero-setisoff 1minordivision, thiswould be about0.8IlVofdc,equivalenttoabout 0.2mvofrf.AtI mvofrf(IJlOthfullscale)about ISIlvdcisdevelopedattheprobeo

40、utput,meaning thattheerrorinzero-setwould be only5%ofthe reading.Atfullscaleitwould only beabout0.05%. 3-26.Ifthisprobetipisconnectedtoatestset-up whichisatadifferenttemperaturethantheprobetip thezeroindicationwilldriftuntil bothdiooesinthe probeareatthesametemperature. 3-27.INTERPRETINGREADING. 3-2

41、8.Nointerpretationofthemeterreadingis necessarywithcontinuoussinusoidalsignals.This meansforalmostallofyourmeasurementstheread- ingonthemeterwill bethermsvalueofthesignal. Theusualconditionsapplythatthefrequencyofthe signalmustbeintherangeoftheinstrumentandthe dccomponentisnotmeasured. 3-29.When ano

42、n-sinusoidalwaveformismeasured thereadingobtainedmustbeinterpretedwithrespect totheparticularwaveformbeingmeasured.Thedc voltagedevelopedbytheSignaliscomparedwithan almostequaldcvoltagedevelopedbythesinusoidal voltagefromthe100 kcoscillator.Sincethewave- formsofthetwovoltagesaredifferent,thepeak vol

43、tageneededtodeveloptheseequaldcvoltagesis different. 01193-1 Model 411A . Section1Il Figure3-9 - l.,-:=-:.-/;i.;=:-H-7 TIP I I I IRf IDC t- DIODE L DETECTOR I I I COMPARATORLDDP-CAIN CATHODE I I ANDI-EQUALIZINCI-AMPLIfiER - DEMODUlATORf-fOllOWER I II I MODULATORAITENUATOROUTPUT I ACfEEDBAC! I I DIOD

44、E I J I J I DC I DC IDETECTORI -TV+l00V I *rBIA -IV I I IZEROI I I I l_,-, I IMODULATED L_J I CLASSC4- 100!C I OSCILLATOR I AMPLIfiER I I I RANCESWITCH0-.- TUNED I IOUTPUT IAMPLIfiER I I I I I ICATHODE IfOllOWER ACfEEDBAC! RANCE 100!CAC IUP DOWN ATTENUATDR RECORDERMETER OUTPUTCIRCUIT ,. FIgure4-1,Bl

45、ock D13gram 01193-14-1 SectionIV Paragraphs4-6to4-26 4-6.Sincethegainof theamplifierishigh andthe feedbackloopisconnectedasaservosystem,the levelintheamplifierwillautomaticallyadjustitself untilthedcdevelopedbythe100 kcverynearlyequals thedcdevelopedbythesignalbeingmeasured.The rangeattenuatarsetsth

46、eratioofthe100 kcfeedback. Theloop-gainequalizingattenuatorkeepsthelOop- gainconstantwhen therangeattenuatorisswitched. 4-7.PROBE. 4-8.Keferringto theschematicdiagram,nocethat theprobetipsmaybesubstitutedforoneanotherso thattheparticularonebestsuitedforaparticular applicationmaybeused.Allprobetipsco

47、maina blockingcapacitor.Inadditiontablockingdc,this capacitoristhechargingcapacitorfortherfdetector diodeCRI. 4-9.Intheprobebodyitselfthereisacartridge containingthetwodetectordiodesandassociated componentsinclosethermalcontact.As theambient temperatureof theprobechanges,thetemperature of bothdiodes

48、changesinasimilarmannertendingta balanceoutthechangesinrectificationcharacteristics withtemperature. 4-10.MODULATOR. 4-11.Thesignaltobemeasured,whichiscoupled throughtheprobe-tipcapacitor,isrectifiedby CR1. Theresultantdcisfilteredby RIOandCll.and appliedtoachopper-typemodulatorcomainingtwo photo-conductivecells,V1 and12,whicharealter- natelyexposedtolight.Theoutput ofthemodulator isasquarewavewhichisproportionaltothediffer- encebetweentherectifiedcomparisonsignalandthe rectifiedincomingsignal. 4-1