Kenwood TS-950S Service Manual

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TS-9505/SDCIRCUITDESCRIPTIONowe(C2:MFIOCCWM 1Clock inputSCAF12iea¢AFTSWH"SAFO—foan7iTats7703ae|2pCoyOFSKC"1Bas)|Inue(CsDtasSsac{b/4)1¢5feaie|IcsaaTerminalfunctionof IC2bazarig2,19:BandpassfilteroutputOG3,18:ConnectionofresistorforchangingOes4,17>InputAbC=®tao5,16:Analogground(+5V}eaeicotesa)ii7.8:Powersupply{+10V)i10,11:Clockinput1c?Flg.12BasicconfigurationFig. 11 AF VBT circuit» Auto antenna tunerWhen the AUTO/THRU switch is set to AUTO, ATAgoes low, the AUTO/THRU switching relay K1 closes,and the AT is inserted to prepare for tuning.When the AT TUNE is turned on, ATS goes high andQ10 turns on. !f the VSWR is greater than 1.2, Q7 alsoturns on. A pulse with the appropriate duty cycle forthe VSWR is obtained from the pulse control circuitconsisting of 1C8 and IC7 (a/2) and is used to drive 6and turn Q4 on and off. This produces the motorcontrol signal that controls the motor drive ICs (IC4 and+15VAUTO/ THRU.Cre,/AT TUNEvMAIN CPU MAIN CPUof IC2 (MF10CCWM)iC5).TheoutputfromthecollectorofQ7isdirectedtothedigitalunit asan"'OK''signal(lowwhentuningiscompleted)indicating thecompletionofATtuning.ATSisalsofedtotheRFunit.Thetransmitter outputduring tuningislimitedtoapproximately10W.TheVSWRiscalculatedfromtheforwardwaveandreflectedwavevoltagesVSFandVSR,anddetected byfilterunitL1viathemicroprocessorinthedigitalunit.TheVSWRisconvertedtoananalogvoltageintherangeof0to5Vaccordingtotheresults ofthiscalculation,andisthenappliedtotheVSWRline.VSWRfe)LegCompletion : LowWhen SWR is high : HighMotor controlFig. 13 Auto antenna tuner circuit24