Kenwood NXR-700H Service Manual

NXR-700H35So, two DSPs can be executed by a +/–0.4ppm clock de-viation.Q300 is a 19.2MHz buffer amp signal input from thetransmitter unit (X56-311).The signal from the transmitter unit is supplied to IC315pin8 (reference signal input).12.288MHz from X300 is amplified by Q304 and dis-tributed to two routes. One is amplified by Q305 and inputto IC315 pin6 (RF signal input). The other is amplified byIC313 and becomes a clock for the RX DSP and TX_VocoderDSP.IC315 compares the reference signal and RF signal anddetects their phase errors.This phase error signal is output from pin2 charge pump(CP), passed through the LPF and is supplied to X300 volt-age control pin1.7. Display Circuit7-1. Display circuitThe display circuit (X56-311 B/3,C/3) consists of varioustypes of LEDs, 17-segment type D960, D961 (red), D921(red: transmission), two-color type D920 (green: busy), D922(green: power on, red blinking: abnormal voltage), D923(green: CTRL), two-color type D924 (red: OCXO error, green:OCXO normality, orange: external reference signal), 8-bitstatus LEDs D925 to D932, and LEDs with built in switchesS920 to S925.IC920 to IC925 and IC960 to IC963 are in charge of dis-playing present channels and states on the front panel.IC923 to IC925 and IC960 to IC963 are shift registers thatconvert the MPU serial data to parallel data and turn onLEDs.7-2. Key switches circuitThe logic signals from the front panel key and channelswitches (channel selector) are entered directly into the RFMPU (IC34).Shift registerIC925SR_CLKSR_DATASR_OEPF KEY1~6SR_DATAShift registerIC924SR_CLKSR_DATASR_OEDATASQShift registerIC923SR_CLKSR_DATASR_OEDATASQCTRLSTATUS LED1~8POWER TX BUSY OCXOSWSW SW SW SW SWSQShift registerIC963SR_CLKSR_DATASR_OESR_CLKSR_DATASR_OEDATASW SWSQShift registerIC962DATA SQSR_CLKSR_DATASR_OEShift registerIC960DATA SQSR_CLKSR_DATASR_OEShift registerIC961DATA SQKEY LED1~6SW SWD961SW SWD960SWCIRCUIT DESCRIPTION / 电路说明因此，可通过 +/-0.4ppm 时钟偏移来执行两个 DSP。Q300是从发射机单元 (X56-311) 输入的 19.2MHz 缓冲放大器信号。发射机单元的信号被提供给 IC315 针脚 8( 基准信号输入 )。来自 X300 的 12.288M H z 由 Q304 放大并分配到两路。一路由 Q305 放大并输入 I C315 针脚 6( R F 信号输入 )。另一路由IC313 放大，变成 RX DSP 和 TX_ 声码器 DSP 的时钟。I C315 将基准信号和 R F 信号进行比较，检测它们的相位误差。该相位误差信号从针脚 2 电荷泵 (CP) 输出，通过 LPF 提供给 X300 电压控制针脚 1。7. 显示电路7-1. 显示电路显示电路 (X56-311 B/3、C/3) 由各种 LED、17 段式 D960、D961( 红色 )、D921( 红色 : 发射 )、双色式 D920( 绿色 : 繁忙 )、D922( 绿色 : 电源开，红色闪烁 : 异常电压 )、D923( 绿色 :CTRL)、双色式 D924( 红色 : OCXO 错误，绿色 : OCXO 正常，橙色 : 外部基准信号 )、8 位状态 L E D D925 至 D932、以及带内置开关的 LED S920 至 S925 组成。I C920 至 I C925 和 I C960 至 I C963 负责在前面板上显示当前的信道和状态。IC923 至 IC925 和 IC960 至 IC963 是将 MPU串行信号转换为并行数据并打开 LED 的移位寄存器。7-2. 键开关电路前面板键和信道开关 ( 信道选择器 ) 的逻辑信号被直接输入 RF MPU(IC34)。Fig. 27 Shift register circuit (Display part) / 图 27 移位寄存器电路 ( 显示部分 )