Kenwood TK-360G Service Manual

Also see for TK-360G: Instruction manual Instruction manual Service manual

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TK-360G/(N)/370G/(N)18Fig. 3 Wide 5K/Wide 4K changeover circuitCIRCUIT DESCRIPTION1. Frequency configurationThe receiver utilizes double conversion. The first IF is 49.95MHz and the second IF is 450 kHz. The first local oscillatorsignal is supplied form the PLL circuit.The PLL circuit in the transmitter generates the necessaryfrequencies. Fig. 1 shows the frequencies.Fig. 1 Frequency configuration1) Front end (RF AMP)The signal coming form the antenna passes through thetransmit/receive switching diode circuit, (D3,D7) passesthrough a BPF, and is amplified by the RF amplifier (Q301).The resulting signal passes through a BPF and goes to themixer.2) First mixerThe signal from the front end is mixed with the first localoscillator signal generated in the PLL circuit by Q19 toproduce a first IF frequency of 49.95 MHz.The resulting signal passes through the XF1 MCF to cutthe adjacent spurious and provide the optimumcharacteristics, such as adjacent frequency selectivity.Fig. 2 Receiver sectionANT TX/RX : 440~470MHz (E, (N)E)TX/RX : 403~430MHz (E4, (N)E4)ANTSWRFAMPPAAMPTXAMPMCF49.95MHz 50.4MHzCF450kHzIFSYSTEMAFAMP SPRX : 390.05~420.05MHz (E, (N)E)RX : 353.05~380.05MHz (E4, (N)E4)16.8MHzPLLVCOX3multiply TCXOMICAMP MICTX : 440~470MHz (E, (N)E)TX : 403~430MHz (E4, (N)E4)2. ReceiverThe frequency configuration of the receiver is shown in Fig. 2.IC4IF, MIX, DETAF AMPIC16 (2/2)X3 multiplyQ12 TCXO5DE-EMP MUTEEXPHPF LPF HPF BEFIC14 2 141SPAF AMPIC11AF AMPIC15(2/2) AF VOLANTSWBPFRFAMPQ301ANTMIXERQ191st LocalIF AMPQ22BPF MCFXF1CF1 : Wide E, E4Narrow (N)E, (N)E42nd LocalPLLVCOR75Q23R98R108C133 CD1"H" : Wide 5K"L" : Wide 4KMXOIFIMXIIFOAFO IC4FM IF SYSTEMQ225RWide 5K / Wide 4KC107R74C108CF1QADR1053) IF Amplifier circuitThe first IF signal is passed through a four-pole monolithiccrystal filter (XF1) to remove the adjacent channel signal.The filtered first IF signal is amplified by the first IF amplifier(Q22) and then applied to the lF system IC (IC4). The IFsystem IC provides a second mixer, second local oscillator,limiting amplifier, quadrature detector and RSSI (ReceivedSignal Strength Indicator). The second mixer mixes the firstIF signal with the 50.4MHz of the second local oscillatoroutput (TCXO X3) and produces the second IF signal of450kHz.The second IF signal is passed through the ceramic filter(CF1) to remove the adjacent channel signal. The filteredsecond IF signal is amplified by the limiting amplifier anddemodulated by the quadrature detector with the ceramicdiscriminator (CD1). The demodulated signal is routed tothe audio circuit.4) Wide 5K/Wide 4K changeover circuit (without (N)E,(N)E4)The Wide 5K (high level) and Wide 4K (low level) data isoutput from IC5 (OUTPUT EXPANDER), pin 4.Q23 turns on/off with the Wide 5K/Wide 4K data and theIC4 detector output level is changed to maintain a constantoutput level during wide or narrow signals.