BAOJIE BJ-9900, Руководство по обслуживанию

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QUANZHOUBAOJIE ELECTRONICS CO.,LTD. Model:BJ-9900
Version:BJ-9900-0812-V1 Page 5 of 75
RF amplifier Q1002 through another low pass filiter network.
Amplified 430MHz signal transmits to Tuned vibration variable resistance filter
network through the switch D1009,which include D1011.D1012 ,D1013 and related
circuit. and then it transmits to the first mixer Q1005.Meanwhile UHF local oscillator
signal which comes from UHF-VCO/AQ1123 transmit to the first mixer Q1003 and
generate first IF of 49.95MHz Sub-band
Sub-band 144MHz Signal
144MHz signal transmits to Antenna through a high pass filter network, and a low pass
filter network switching diode D1113,D1114,D1115, D1116 and D1117 then transmit to
Main band RF amplifier Q1015 through another low pass filter network.Amplified
144MHz signal transmits to first mixer Q1017 through Tuned vibration variable
resistance filter network including D1020.D1021 ,D1022 and related circuit.
Meanwhile VHF local oscillator signal which comes from VHF-VCO/AQ 1126 transmit
to the first mixer Q1017 and generate first IF of 49.95MHz sub-band .
Sub-band IF and audio signal
49.95MHz sub-band first IF signal is sent to the crystal filter FL1003 and FL1004. The
crystal filter remove those unwanted mixer products, and then through the IF amplifier
Q1035 sent to IF IC IC1047.
Meanwhile the 16.8MHz Crystal part X1003export the triple frequency via Q1043
to generate 50.4MHz second local oscillator signal and transmits to IF IC1047 where
50.4MHz second LO and 49.95MHz sub-band first signal mixed to be 450KHz
sub-band second IF.
{450KHz sub-band second IF transmit to Ceramic Filter CF1003 which remove the