Kenwood TK-3160 Service Manual

Also see for TK-3160: Service manual Specifications Instruction manual Instruction manual Specifications

Contents

TK-31609CIRCUIT DESCRIPTIONFig. 8 Microphone amplifierFig. 9 Drive and final amplifier and APC circuit4. Transmitter System1) Microphone AmplifierThe signal from the microphone passes through IC601.When encoding DTMF, it is turned OFF for muting themicrophone input signal by IC601.The signal passes through the Audio processor (IC601) forthe maximum deviation adjustment, and goes to the VCXOmodulation input.2) Drive and Final AmplifierThe signal from the T/R switch (D201 is on) is amplified bythe pre-drive (Q206) and drive amplifier (Q207) to 50mW.The output of the drive amplifier is amplified by the RF poweramplifier (Q211) to 4.0W (1W when the power is low). TheRF power amplifier consists of two MOS FET stages. Theoutput of the RF power amplifier is then passed throughthe harmonic filter (LPF) and antenna switch (D204 andD206) and applied to the antenna terminal.FromT/R SW(D201)DRIVEAMPRFPOWER AMP LPFANTSWD204D206ANTVGVGQ207 Q211Pre-DRIVEAMPQ206VDDRFAMPQ205VGR256R257R261+BIC201(1/2)IC201(2/2)PCTV(IC805)IC601IC805LPFDTMF/2 TONELSDTCXOLSDVCOCPUAGCVCOMICX1TCXOLPFLPFAQUA3) APC CircuitThe APC circuit always monitors the current flowing throughthe RF power amplifier (Q211) and keeps a constant current.The voltage drop at R256, R257 and R261 is caused by thecurrent flowing through the RF power amplifier and thisvoltage is applied to the differential amplifier IC201(1/2).IC201(2/2) compares the output voltage of IC201(1/2) withthe reference voltage from IC805. The output of IC201(2/2)controls the VG of the RF power amplifier, Drive amplifierand Pre-Drive amplifier to make both voltages the same.The change of power high/low is carried out by the changeof the reference voltage.4) Encode Signalling(1) QT/DQTQT,DQT data of the LSDTCXO Line is output from pin 22 ofthe CPU. The signal passes through a low-pass CR filterand goes to the TCXO(X1).The QT,DQT data of the LSDVCO Line is output from pin3) Unlock DetectorIf a pulse signal appears at the LD pin of IC1, an unlockcondition occurs, and the DC voltage obtained from C19,R6, and Q1 causes the voltage applied to the microprocessorto go high. When the microprocessor detects this condition,the transmitter is disabled, ignoring the push-to-talk switchinput signal.(See Fig. 7)Fig. 7 Unlock detector circuitFig. 6 PLL circuitPLL DATAX116.8MHzREF OSC1/M1/NPLL IC IC1PHASECOMPARATORCHARGEPUMPLPF5kHz/6.25kHzD4,7D3,9Q6TX VCOQ5RX VCOQ9BUFF AMPQ11RF AMPRXTXQ7RF AMPQ8, 12T/R SW5kHz/6.25kHzLPF5CR6Q1C19R7IC805IC1LDULPLL ICCPUR16