Kenwood TK-3000 Service Manual

Also see for TK-3000: Instruction manual Quick manual Instruction manual Instruction manual Instruction manual

Contents

TK-300071. Frequency ConfigurationThe receiver utilizes double conversion. The first IF is38.85MHz and the second IF is 450kHz. The first Local os-cillator is supplied from the PLL circuit.The PLL circuit in the transmitter generates the neces-sary frequencies.CIRCUIT DESCRIPTION2. Receiver SystemThe receiver system is shown in Figure 2.Fig. 1 Frequency configurationFig. 2 Receiver system2-1. Front End (RF Amplifier) CircuitThe signal coming from the antenna passes through thetransmit/receive switching diode circuit (D101, D102, D103and D105) and a BPF (L208 and L210), and is then ampli-fied by the RF amplifier (Q204).The resulting signal passes through a BPF (L215, L218and L219) and goes to the mixer. These BPFs are adjustedby variable capacitors (D201 D202, and D204). The inputvoltage to the variable capacitor is a regulated voltage out-put from the DAC (IC300).2-2. First MixerThe signal from the front end is mixed with the first localoscillator signal generated in the PLL circuit by Q203 to pro-duce a first IF frequency of 38.85 MHz.The resulting signal passes through the XF200 MCF tocut the adjacent spurious and provide the optimum charac-teristics, such as adjacent frequency selectivity.TX/RX: 400~430/440~480MHz1st MIX MCF SPMICCF450kHzANTANTSWRFAMPIFSYSTEMX2doublerPLLVCO38.85MHz 38.4MHzTXAMPRFAMPAFAMPMICAMPAFfilterTCXO 19.2MHz361.15~391.15/401.15~441.15MHz400~430/440~480MHzSPANTIC200IF,MIX,DETQ2031st MIXIC303CF200ANTSWQ201X2 doubler2nd LocalX1TCXO19.2MHzBPFBPFQ204RF AMP XF200MCFQ202IF AMPIC302AF PABPF 1st LocalBPF AFfilter VR500