Kenwood NXR-700H Service Manual

NXR-700H274-8. AVR circuitThe power supply voltage supplied from the power unit(X45-385 C/5) is distributed from the receiver unit (X55-309)CN44 to IC24 (8V), IC25 (8V), IC26 (9V), and IC27 (9V) viathe Q52 DC switch. The output of IC24 is supplied to the1st-IF circuits, the 1st-Local amplifiers and the IF system IC_IC12 via IC15 (5V). Further, the output of IC25 is distributedto IC16 (5V), IC17 (5V), IC18 (5V) and IC19 (5V). The outputof IC16 is supplied to IF system IC_IC13. The output ofIC17 is supplied to the 2nd-Local amplifiers. The output ofIC18 is supplied to the 1st-PLL and the 2nd-PLL. The outputof IC19 is supplied to the DDS circuit. The output of IC26 issupplied to LNA_Q1. The output of IC27 is supplied to theVCO buffer amplifiers_Q17, Q33, the 1st-VCO and the 2nd-VCO via Active ripple filters_Q9, Q27, and to the Active loopfilter_Q2, Q4 via the Active ripple filters_Q6.SW +8V+5VCN44+B Q52SWQ32IC24+5VIC16+5VIC17+5VIC18+3VIC10+3.3VIC22+5VQ9Q27Q6IC19+8VIC25Q18,231st local amplifiersIC142nd IF amplifierIC19Pre-scalerQ21,532nd local amplifiersIC13IF systemICQ19,28WIDE passSWQ25Q20,29Narrow passIC15IC12IF system ICQ1LNA (Collector)Q1LNA (Emitter)+9VIC26+9VIC27+5VIC701–5VIC702–3VIC703IC5,111st/2nd PLLʹsIC7DDSQ17,331st/2nd VCO buffer amplifiersQ7,81st local VCOʹsQ242nd local VCOQ2,4active loop filter4-9. Other circuitsOther circuits include the EEPROM (IC31), the temper-ature sensor IC (IC35), the DAC (IC23) and the ADC (IC30).IC31 saves various adjustment values of the receiver unit.IC35 is built-in for detecting changes in temperature. IC23offsets the RSSI voltage (pin1) (detected by the IF systemIC (IC12)) and the 1st-VCO_A, VCO_B control voltage (pin2,pin3).IC30 monitors the 1st-VCO control voltage (pin16), theLNA current detection value (pin15), the temperature de-tected by the temperature sensor IC (IC35 pin14), the RSSICIRCUIT DESCRIPTION / 电路说明4-8. AVR 电路功率单元提供的电源电压从接收机单元 ( X55-309) C N44经 Q52 D C 开关分配到 I C24(8V )、I C25(8V )、I C26(9V ) 和IC27(9V)。IC24 的输出经 IC15(5V) 提供给第 1 IF 电路、第1 本地放大器和 IF 系统 IC_IC12。此外，IC25 的输出被分配到 IC16(5V)、IC17(5V)、IC18(5V) 和 IC19(5V)。IC16 的输出被提供给 IF 系统 IC_IC13。IC17 的输出被提供给第 2 本地放大器。IC18 的输出被提供给第 1 PLL 和第 2 PLL。IC19 的输出被提供给 DDS 电路。IC26 的输出被提供给 LNA_Q1。IC27的输出通过有源纹波滤波器 Q9、Q27 提供给 V C O 缓冲放大器Q17、Q33、第 1 V C O 和第 2 V C O，通过有源纹波滤波器 Q6 提供给有源环路滤波器 Q2、Q4。Fig. 22 AVR circuit / 图 22 AVR 电路4-9. 其它电路其它电路包括 E E P R O M ( I C31)、温度传感器 I C ( I C35)、DAC(IC23) 和 ADC(IC30)。IC31 保存接收机单元的各项调整值。IC35 为内置式，用于检测温度变化。IC23 偏置 RSSI 电压 ( 针脚 1)( 由 IF 系统 IC (IC12) 检测 ) 和第 1 VCO_A、VCO_B 控制电压 ( 针脚 2、针脚 3)。IC30 监测第 1 VCO 控制电压 ( 针脚 16)、LNA 电流检测值 ( 针脚 15)、温度传感器 IC (IC35 针脚 14) 检测的温度、IF 系统