Kenwood NXR-800 Service Manual

Also see for NEXEDGE NXR-800: Brochure Instruction manual Instruction manual Instruction manual Instruction manual

Contents

NXR-800143-8. FAN action control circuitThe FAN action control circuit consists of a FAN, a currentdetection resistance (R11), a Differential amplifier (IC15), aSwitching FET (Q3), and a Switching FET (Q14). It detectsthe normal and abnormal state by monitoring the currentflowing FAN motor, and stops operation when failure oc-curs.Q3SWMQ14SWIC12AVRIC15Diff. AMP FAN_CURRFAN_CONTVBATTR11Fig. 13 FAN action control circuit3-9. Current detector circuitThe current detector circuit monitors the current of thePower Amplifier Module. It consists of a current detectionresistance (R4) and a current detection IC (IC1). It detectsthe normal and abnormal state of the Power Amplifier Mod-ule by monitoring the current of the Power Amplifier Mod-ule. If a failure occurs, it stops operation.IC1Currentsense ICPA_CURRR4Fig. 14 Current detector circuit3-10. AVR circuitIC3, IC11 and IC12 are AVR ICs.They maintain isolation of each power supply.+8VIC11+5VIC12+5V OP AMPOP AMPIC3SWQ4,5SWQ3,14ANT SWTempprotection ICFANPower amplifiermoduleCN2+VBATTIC2,5,8IC10IC6IC7Fig. 15 AVR circuit3-11. Other circuitsCircuit IC9 saves various adjustment values of the FinalUnit in the EEPROM.4. Receiver UnitThe receiver unit (X55-310) consists of the following cir-cuits:(1) Front-end circuit(2) 1st-Mixer circuit(3) 1st-IF circuits(4) Demodulator circuits(5) Squelch circuit(6) Receiver DDS circuit(7) Receiver PLL circuits(8) AVR circuit(9) Other circuitsThere are four modulating modes that can receiver de-modulate, including Analog_Wide, Analog_Narrow, NXDN_Narrow, and NXDN_Very-Narrow.4-1. Front-end circuitThe front-end circuit consists of L132 and L133 helicalBPF, Q1 Low Noise Amplifier (LNA), and L134 and L135 he-lical BPF. Adjusting four helical BPF forms the BPF having apass band width of 5MHz with a center frequency from 450to 480MHz.+9V is applied to the Q1 collector power supply. -3V pro-duced by IC701, IC702 and IC703 mounted on a negativepower unit (X45-382 D/5) is applied to the emitter powersupply. The collector current is monitored by the IC4 cur-rent detection circuit. Detected DC voltage is input to pin15 of IC30 (ADC).BPFL132,133BPFL134,135Q1LNAIC4IC30+9V15RX ANTCN5RX unitX55-310IC701+9V IC702+5V IC703–5V –3VPower supply unitX45-382 D/5CN701Fig. 16 Front-end circuitCIRCUIT DESCRIPTION