Kenwood TK-860G Service Manual

Also see for TK-860G series: Instruction manual Instruction manual Service manual supplement Service manual Service manual

Contents

26TK-860G/862GD102,104Q103TX VCOQ106BUFFAMPD101,103Q101RX VCO Q102,104,105T/R SWChargepumpLPFPhasecomparator1/M1/NPLL/VCO5kHz/6.25kHz5kHz/6.25kHzREFOSC16.8MHzPLLDATAIC3 : PLL ICQ9RF AMPFig. 6 PLL circuit Unlock CircuitDuring reception, the 8RC signal goes high, the 8TC sig-nal goes low, and Q16 turns on. Q18 turns on and a voltageis applied to the collector (8R). During transmission, the8RC signal goes low, the 8TC signal goes high and Q29turns on. Q28 turns on and a voltage is applied to 8T.The CPU in the control unit monitors the PLL (IC3) LDsignal directly. When the PLL is unlocked during transmis-sion, the PLL LD signal goes low. The CPU detects thissignal and makes the 8TC signal low. When the 8TC signalgoes low, no voltage is applied to 8T, and no signal is trans-mitted.IC9SHIFTREG.IC502CPUQ16SWQ18SWIC3PLLQ29SWQ28SWLDCONTORL UNIT8RC8C8R 8T8TCPLL lock: LD "H"Fig. 7 Unlock circuitQ22RF AMP2SC4093Q25RF AMP2SC3357Q27ANTRF AMP2SC2954IC400POWER AMPS-AU27AM(K3) : K,MS-AU27AL(K3) : K3Q14BUFFER2SC5110(O)IC508 IC6 Q103IC507(1/2)MICAF AMPNJM2904VMIC KEYINPUTAF AMP,IDC, LPFTC35453FIC502CPU30622M4XXXGPD/ACONVERTERM62363FPIC1SUM AMPTA75S01FX1VCXO16.8MHzVCO2SK508NV(K52)IC3PLLMB15A02Q106BUFFER2SC4226(R24)Q9BUFFER2SC4215(Y)Fig. 8 Transmitter systemTransmitter System OutlineThe transmitter circuit produces and amplifies the de-sired frequency directly. It FM-modulates the carrier signalby means of a varicap diode Power Amplifier CircuitThe transmit output signal from the VCO is amplified to aspecified level of the power module (IC400) by the driveblock (Q22, Q25 and Q27). The amplified signal passesthrough the transmission/reception selection diode (D16)and goes to a low-pass filter. The low-pass filter removesunwanted high-frequency harmonic components, and theresulting signal is goes the antenna terminal.CIRCUIT DESCRIPTION