Kenwood TS-770 Service Manual

Also see for TS-770: Service manual Operating manual

CIRCUITDESCRIPTION(From page 11.)aSelectorsignalourputtoIC34and35.Transmitprohibit signalatscan,search andFIX empty.Latchstrobesignal10 Hz ~ 400 kHz data ourputBanddataoutputFIXchannelfigureoutputBuzzer pulse outputALLASS'Y UNIT (X60-1050-00)ThePLLcwcurtincludes VCO,ALOOPand 8LOOPunits.1, B LOOP UnitAsignalof13.215MHzisoscillatedbyQ4.The10and100kHzdatafromthedigitalunitareconvertedintoananalogsignal a8abias signaltoD2bythe resistorsA25-37(0controlthefrequencyof0-980Hz.Thefrequency1sdoubledbyQ6as3HETsignaltotheBLOOP.Q1isVCOoscillatorforBLOOP.Thesignalfromtheoscillatorpasses throughthebutterO3andismixedwithCAR8.83MHzbyICT.thenthefrequencydifferenceismixedwithHETsignalfor8LOOPbyIC2_The1kHz-100kHzdatafromthedigitalunitisdividedbyIC3toproduce1kHzsignal.This signal1scomparedinphasewiththereferencesignalfromALOOPby14.Theoutputpassesthroughthelow passfilterQ6-810produceVCOcontrolvoltageforBLOOPtocontrolQ1Theoutput fromQ1passesthroughthe bufferQ2toproducetheoutputtoBLOOP2. A LOOPAsignalof14.190MHzisoscillatedbyQ1.This signalisdoubledbyQ2andtripledbyQ3toproduceHETsignalforALOOPThesignalfromtheVCOunitismixedwith theHETsignalby(C1,amplifiedby.IC2andthenmmxedwiththesignaltrom8LOOPbyIC3.TheBANDdatafromthedigitalunitisfedtoIC4sothatthesignalfromIC318dividedinto100kHa.Asignalof8MHz1soscillatedbyICS.Thissignalisdividedtoobtain100kHzsignalasreference signalsfor8LOOPandA.LOOP,andiscomparedinphasebyIC6.TheoutputfromIC6isVCV whichontrolsVCOof theVCOunitAnalogsignalfromtheBANDdataisobtained fromIC7ThissignalistunedbyT1andT2toobtain5MHzbandwidth‘Whenthe signal1sunlocked,D4ofD5isON. producingUKsignalofHlevel3.VCOUnit(X50-1520-00)Frequenciesarecontrolled bytheVCVvoltageofVCO[01)Thesignalpasses throughthe bufferQ2andisfedtoAloopQ3andQ4form the buffer ofVCO.Whenthe signal1sun-locked, theUKsignal turnsQ9toONand tumsQ8toOFF.80 the butfer stops and no outputisobtained from theVCOterrninalQ6 and Q6 forma circuit toshort theVCVterminalwhenthevoltageatPL8 drops momentarily.Whenthesignalisunlockedduringadjustmentsorrepairs,turnOFFthepowerswitchandthenturnON.ThesignalwillthenbelockedSesssaiaoe)‘Ai om (9CDv5Fig.19PLLIANC3 PLL(B)IC2ITA7310P)13