FP520 Service Manual
Page 6 of 64
Chapter 3 Circuit Description
3.1 Overview
This radio is FM portable equipment.
3.2 Frequency Configuration
ANT SW
RF
AMP
PA
AMP
TX
AMP
PLL
VCO
IF SYSTEM
X4
multiply
TCXO
12.8MHz
51.65MHz
MCF
CODEC
AF
AMP
MIC
CF
450KHz
ANT
MIXER
Fig 3.1 Circuit Diagram
This Radio applies twice frequency mixing method. The first intermediate-frequency is 51.65MHz. The second
intermediate-frequency is 450 kHz.
The first local oscillation is generated by frequency synthesizer, and the second local oscillation is generated by the
quadruple frequency of 12.8MHz.
The transmitting signal is generated by frequency synthesizer.
The reference frequency of frequency synthesizer is generated by TCXO.
3.3 Principle of Receiver (RX)
ANT SW
BPF
1st local
osc
BPF
MCF
IF AMP
Q701
IF DET
450K
CODEC
AF PA
SPK
D600 D601
D602 D603
MIXER
Q702
Z1
51.65MHz
U6
U800
ANT
X4
Multiply
Q300
TCXO
MCU
IC2
PC/TV
Q703
RF AMP
CF1
Fig. 3.2 Principle of Receiver
Summary of Contents for FP520
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Page 44: ...FP520 Service Manual Page 43 of 64 Figure 1 FP520 01 Mainboard Schematic Diagram 136 174MHz ...
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Page 54: ...FP520 Service Manual Page 53 of 64 Figure 4 FP520 02 Mainboard Schematic Diagram 400 470MHz ...
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Page 64: ...FP520 Service Manual Page 63 of 64 Figure 7 KBC 51 7 4V Electrical Schematic Diagram ...