Kenwood TK-2317 Service Manual

Also see for TK-2317: Service manual Specification Instruction manual Instruction manual

Contents

TK-231725CIRCUIT DESCRIPTION / 电路说明phase comparator, and charge pump. The input signal frompin 10 and 17 of the PLL-IC is divided down and comparedat the phase comparator. The pulsed output signal of thephase comparator is applied to the charge pump and trans-formed into a DC signal in the loop filter (LPF). The DC sig-nal is applied to the CV of the VCO and locked to keep theVCO frequency constant.PLL data is output from PL_STB (pin 20), PL_CLK (pin 8),and PL_DAT (pin 21) of the MCU (IC820). The data is inputto the PLL-IC when the channel is changed or transmissionis changed to reception and vice versa. PLL lock condition isalways monitored by pin 18 (PL_UL) of the MCU. When thePLL is unlocked, PL_UL goes low.5. Control CircuitThe control consists of the MCU (IC820) and its peripher-al circuits. It controls the TX-RX unit. IC820 mainly performsthe following;1) Switching between transmission and reception by PTTsignal input.2) Reading channel information, frequency, and programdata from the memory circuit.3) Sending frequency program data to the PLL.4) Controlling squelch on/off via the DC voltage from thesquelch circuit.5) Controlling the audio mute circuit via the decode data in-put.6) Transmitting tone and encode data.5-1. Frequency Shift CircuitThe MCU (IC820) and baseband IC (IC812) operates ata clock frequency of 19.2MHz. The oscillator circuit has thebaseband IC. This oscillator has a circuit that shifts the fre-quency via Beat shift switch (Q806).A beat sound may be able to be evaded form generationif “Beat Shift“ is set to ON when it is generated in the internalspurious transmission modulated sound of the transceiver.RFAMPBasebandICVCOPLLMCUIC820PL_STB,PL_CLK,PL_DATIC1PL_UL1710217BUFFSWLPFTo mixerVCQ9BUFFQ8TCXOX1 IC812SW ToRF AMPTX/RX(TX: High)D18D17Q2CVFig. 6 PLL block diagram / 图 6 PLL 方块图PLL 数据从微处理器 (IC820) 的 PL_DAT( 针脚 21)，PL_CLK( 针脚 8) 和 PL_STB( 针脚 20) 输出。当信道改变时，或当由发射变为接收或由接收变为发射时，数据输入 PLL IC。PLL的锁定条件总是由微处理器的针脚 18(PL_UL) 监控。当 PLL失锁时，UL 为低电位。5. 控制电路控制电路是由微处理器 (IC820) 和外部电路构成。它控制收发单元。IC820 的主要功能如下 :1) 根据 PTT 的输入信号来转换发射和接收状态。2) 从存储电路读出信道信息、频率以及编程数据。3) 发送频率数据给 PLL。4) 根据静噪电路输出的 DC 电压来控制静噪的开启和关闭。5) 根据解码数据控制音频静音。6) 发射 Tone 及编码数据。5-1. 频率偏移电路微处理器 (IC820) 和基带 IC(IC812) 在 19.2MHz 时钟下工作。此振荡器有可以被拍频偏移开关 (Q806) 变换频率的电路。如果“拍频偏移”被设定为 ON，可以避免产生拍频声音。