Kenwood TS-950S Service Manual

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T9-9505/5DCIRCUIT DESCRIPTIONCKY generationWhen the SS line goes high, pin 2 of IC6 also goeshigh, and the Q output of 1C10 goes high after a 10 msdelay. The output of pin 3 of IC6 goes low 10 ms afterthat.The output of pin 10 of IC5 goes high and pin 5 ofthe analog switch of IC4 goes high when in FULLbreak-in operation. Pins 4 and 3 conduct, CKY goeshigh, and the second transmit mixer of the IF unit iskeyed.The CKY output enters the ALC module (X59-3700-00) via D15, passes through the integration circuitQ251 for waveform shaping, and is matched with thenegative signal of ALC to produce the FET gate bias ofthe transmit IF.Generation of RXB when the key is upWhen the key is up, the SS line goes low, and theanode of D16 also goes low. Meanwhile, Q7 turns off,and the CSS line goes high to notify the microproces-sor of the start of reception.Since there is a 5-ms time constant circuit com-posed of R43, R44, and C37 for the output of pin 2 ofIC13, the outputof pin 4 of IC13 goes from high to low5 ms after the SS line switches. Therefore, CTXB goeslow 5 ms after the key goes up, and with a similardelay for the TXB line.When TXB falls, Q154 of the TRX module (X59-3680-00) is turned off, and Q156 and Q151 turn on,causing RXB to rise.CKY down rTWhen the key is up, KYB and SS go low, pin 3 of theNAND gate of IC6 goes high, and thus the CKY linegoes low.RBC generationThe RBC signal is generated in the'same way as formanual standby. The RBC changes from high to low 5ms after RXB rises when the key is released. Thereceiver operates only when RBC is low.10ms 10msCKYRBC Sms“tIFig. 19 Timing chart for full break-in29