Kenwood TK-5310 K4 Service Manual

Also see for TK-5310: Specifications Instruction manual Specifications Instruction manual

Contents

TK-531018CIRCUIT DESCRIPTIONIf an optional scrambler board is installed, the switch(Q454) adjusts the signal path so that the audio signal is inputto the CODEC through the scrambler board.If the optional VGS-1 (Voice Guide & Storage unit) isinstalled, the switch (IC450) will adjust the signal path so thatthe audio signal from the microphone is output to the VGS-1and the audio signal from the VGS-1 is input th the CODEC.The audio signal is input to the CODEC (base band circuit)through the above path.4-2. Base Band CircuitThe base band circuit of the transmitter system consistsof the following:• CODEC (IC454)• DSP (IC8)• LPF (IC456)• Buffer (IC459)• DAC (IC462)• Amplifier (IC463)The audio signal output from the base band circuit isconverted to digital data of a sampling frequency of 48 kHzand a quantization resolution of 16 bits by the CODEC(IC454). This digital data is sent to the DSP (IC8), and voicesignals of 300 Hz or lower and frequencies of 3 kHz or higherare cut off and an audio range 300 Hz to 3 kHz is extracted.The audio signal is then pre-emphasized in FM mode andsynthesized with the signals, such as QT and DQT, asrequired, and is then output from the CODEC. In P25 mode,the audio signal is converted to the C4FM base band signaland output from the CODEC. The DTMF and MSK base bandsignals are also generated by the DSP and output by theCODEC.LPF (IC456) removes quantization noise from the baseband signal output from the CODEC.The buffer (IC459) sets the base band signal level to theDAC input range.The DAC (IC462) assigns the base band signal to the VCO(Q107) and VCXO (X100).At this time, the level output according to the transmitcarrier is fine-adjusted according to the modulation methodof FM Wide, FM Narrow and P25.4-3. Transmit Signal Amplification Circuit(From T/R switch to Final amplifier)The transmit signal passing through the T/R switch(D200) is amplified to approx. 50 mW by the two transistoramplification circuits (Q200, Q210). The transmit signaloutput from Q210 passes through an attenuator to improvehigh-frequency signal matching is amplified by the driveamplifier (Q202) and applied to the final amplifier (Q205). Thesignal applied to the final amplifier is amplified by the finalamplifier so that the antenna output is 4 W (1 W for LowPower).4-4. High-Frequency Signal Switch Circuit(From Antenna switch to ANT output)The transmit signal output from the final amplifier (Q205)passes through the antenna switch (D202, D203) and LPF,and goes into the SPDT switch (IC202, IC203) which changesthe antenna connector (CN204) and the universal connector(CN205).The transmit signal passing through the output changeswitch passes through the surge protection HPF andspurious removing LPF and then goes to the antennaconnector (CN204) or the universal connector (CN205),specified by the SPDT switch (IC202, IC203).4-5. APC CircuitThe APC circuit detects the current of the drive amplifier(Q202) and final amplifier (Q204) during transmission andcontrols the output power by controlling the current.It detects the current using R220 and R222 and applies adrop voltage between both resistors during transmission toAPC (IC201). It controls the transmission current of the driveamplifier and final amplifier so that it is constant bycomparing this current with the reference voltage outputfrom pin 7 of IC200. The reference voltage input to pin 5 ofIC200 is output from the DAC (IC462). High/Low poweroutput is set according to the DAC output voltage.Fig. 6 Audio band and Base band circuitMIC(MAIN)EXT.MICMIC(SUB)MSW/CTSMMIC705 Q455SWQ452SW AGC-AMPIC452LPFD450,D451DETScrambler boardSCSWVGS-1 VATSMICN/CAMPIC462DACQ454SWIC8DSPIC454CODECIC450SWIC456LPFIC459BUFFIC463AMPX100VCXOQ107VCO