philips-bx645a-translated-from-dutch 电路原理图.pdf
PhilipsBX645A TranslatedfromtheDutch. THE PHILIPS TYPE BX 645A AC RECEIVER W.Martens ThereceivertypeBX645Afrom1954isasuperheterodynereceiverwiththe followingrange: shortwaveKG2a:11.36-17.00m_(26.4-17.6MHz); shortwaveKG2b:17,00-25,87m(17.6-11.6MHz); shortwaveKG2c:23,07-32,96m(13.0-9.1MHz); shortwaveKG2d:32.25-60.00m(9.3-5.0MHz); shortwaveKG3:60,00-187,00m(5.0-1.604MHz); mediumwaveMG:187.00-580.00m(1605-517kHz). Thedeviceissuitableforconnectiontoalternatingvoltagesof90-110-125-180- 200and225V.Thefollowingtubeshavebeenused:pentodeEF41(B1)asradio frequencyamplifier,triode-heptodeECH81(B2)asoscillator-modulator,double diodepentodeEBF80(B3)asdetectorandintermediatefrequencyamplifier, doublediodetriodeEBC41(B4)aslowfrequencyamplifierandrectifieratthe serviceofthewaverangeswitch,andpentodeEL84(B5)asaudiofrequency poweramplifier.ThetypeEZ80(B6)servesasarectifierandthecathoderayin- dicatorEM34(B7)hasbeenusedforopticaltuning.Forthescalelighting,2 lights8045D-00(6.3V-0.32A)andfortheindicationofthesetwaverangethere are6lamps8023N-00(GV-0.18A). HIGHFREQUENCY ThecoilsofthefirstHFcircuit,S6forKG2a,S7forKG2bandS8forKG2c,are inductivelycoupledwiththeantennacoilsS1,S2andS3.Theyaretunedwith C1,whichisconnectedinserieswithC2toreducethetuningcapacity.S6,S7and S8areconnectedinparalleltoC3viasch.4andconnectedtoB1scontrolgridvia RadioFans.CN C4.ThecoilsS9forKG2dandS10forKG3areinductivelycoupledwiththe antennacoilsS4andS5.TheyaretunedwithC1andconnectedviaC4toB1s controlgrid.S11/S11aforMGisaferroceptor*),whichisconnectedtothe controlgridontheonehandandisgroundedviaC5ontheotherhand.Itis tunedwithC1.TheanodeofB1isconnectedviaC6withthecoilsofthesecond HFcircuit,S13forKG2a,S14forKG2bandS15forKG2c,whicharetunedwith C7.ThisisconnectedinserieswithC8toreducethetuningcapacity.S13,S14 andS15areconnectedviasch.3inparallelwithC9andviaC1Owiththecontrol gridoftheheptodepartofB2.TheSI6coilsforKG2d,S17forKG3andS18for MG,arematchedwithC7.S16andS17areconnectedtotheanodeofB1viaC6. S16isconnectedviaC10tothecontrolgridoftheheptodepartofB2,S17and S18viatheseriescircuitofC8andCIO.S18isinductivelycoupledwithS12, whichisincorporatedintoB1sanodecircuitviaC6. *)Aferroceptorisarotatablyarrangedferroxcuberodonwhichtheantennacoils aremounted,andwhichhasthesamepropertiesasawindowantenna. Theoscillatorcircuitsarethefollowing: KG2a:thecombinationS23-C11-S29-C12isontheonehandwiththegrid,onthe otherhandviaC13withtheanodeofthetriodepartofB2andisthereforeself- generating(ultraaudioswitching).IntuneisconnectedinserieswithC14,with C15. KG2b:aswithKG2a,butwithS24insteadofS23. KG2c:aswithKG2a,butwithS25insteadofS23. KG2d:thecombinationS26-C16-S30isconnectedviaC13withtheanodeofthe triodepartofB2.IntunewithC14.ThefeedbackcombinationS19-C17-S20is connectedviaC18withthegridofthetriode. KG3:S27withthepadderC19issentviatheseriesconnectionofC13andC15 withtheanode of the triode. Resonance occurs with C14. The feedback coil S21 is connected via R1 and C20 with the grid of the triode. MG: S28 with the padder C21 is through the series connection of C13 and C15 with the anode of the triode part of B2. It is tuned with C14. The return coupling coil S22 is connected to the grid of the triode. MIDANDLOWFREQUENCY ThethirdgridoftheheptodepartofB2isconnectedtothegridofthetriode.By mixingtheauxiliaryfrequencywiththereceivedfrequency,wegetintheanode circuitoftheheptodepartadifferencefrequencyof452kHz.Thisintermediate frequencyispassedthroughthefirstIFbandpassfilterS31-S32onthecontrol gridofthepentodepartofB3.ViathesecondIFbandpassfilterS33-S34comes theamplifiedIFsignalontothe2nddiodeplateofthattube.Thisiswhere detectiontakesplace,asaresultofwhichbyR2,R15andthepotentiometer R3/R4(thevolumecontrol)DCwiththesuperimposedaudioalternatingcurrent willflow.TheaudiovoltagesacrossthevolumecontrolarepassedviaC22for RadioFans.CN amplificationtoB4scontrolgrid.Finalamplificationtakesplacewiththe pentodeB5,passingthroughR5,R6andR.ThepotentiometerR8/R9,connected viaC23withtheanodeofB4,servesforthetonecontrolonthecontrolgridof B5.ForAVR(automaticvolumecontrol)thefirstdiodeplatefromB3through C24isconnectedtotheanodeofthattube.ThealternatingDCvoltagethatarises overRIO,isregardedasanegativevoltageviaR11tothecontrolgridofB3,and furtherviaR12tothecontrolgridoftheheptodepartofB2andviaR13tothe controlgridofBl.C25isusedforsmoothing. InserieswithR14,aportionoftheprimarywindingoftheloudspeaker transformerisusedasachokeinthesmoothingcircuitoftheanodeandscreen gridsupplies. THEWAVERANGESWITCH Thewavebandswitch(sch.1to5)ispoweredbytheelectricmotorM,setby switchessh.6.Thereare6pushbuttonsD1to6.If,forexample,D2(KG2b)is pressed,D1(KG2a),whichiscurrentlyclosed(mechanically)opens.The alternatingcurrent,takenfromS35ofthepowersupplytransformer,thengoes throughZI,themothercontactm,therotorjumpercontactA,therotorcontact2 andD2tothemotorMandthenbacktoS35.Theengineturns,drivingthe coupledsh.6on.AssoonastherecessinAforcontact2hascome,thecircuit becomesdisconnectedandtheenginestops.Thewavechangeswitchthenstays inposition2(KG2b),whichisindicatedbytheindicatorlampL2,whichreceives currentthroughtherotorcontactB,connectedtoA.Iftherotorofsch.6is movedonepositionplace,forexamplefrom1to2,thenthemotorgrindsone revolution.shinterruptsthepoweronceperrotationofsch.6onthemoment therecessisinAforoneofcontacts1to6.Thisalwaysguaranteesthecorrect RadioFans.CN positionofsch6.Ifthecurrentcircuitisbrokenalittletooearlyduetoaslightly incorrectpositionofastatorcontact,thensch7willremaincloseduntilthe motorhasmadeafullrevolution. Toavoiddisturbingnoisesduringswitching,thealternatingcurrentofS35via C26isrectifiedwiththeparallelswitcheddiodesfromB4.Theresultingnegative voltageisappliedtothegridofB4.Thispreventsflowofanode-currentthrough B4. THESERVICE Thereceiverhasonthefrontfivecontrolknobs,fromlefttoright:1.thevolume control,combinedwiththemainsswitch,2.thetonecontrol,3.thefinetuning, whichtakesplacebyshiftingtheironcoreinS29forKG2a,KG2bandKG2cand thoseinS30forKG2d. Knob4isforsettingtheferroceptorandturningiton andofffromtheantenna.Knob5isfornormaltuning.AtthetopleftofKnob1 arethepushbuttonsforcontrollingthewavebandswitchandtotherightabove knob5aretherelevantindicatorlights.Thespeechmusicswitch(sch.8)andthe radiogramophoneswitch(sch.9)arelocatedrespectivelybehindthevolume RadioFans.CN powerswitchknobandthetonecontrolknob.Sh.10istheantennaferroceptor switch. CURRENTANDVOLTAGETABLE ThevoltageacrossC27is270V,thatacrossC28is245V.Theconsumptionofthe receiverisapprox.53W. Keywords:Ferroceptor,Waverangeswitchwithmotor,ReceiverBX645A. RadioFans.CN RadioFans.CN
