Kirisun DR600, Service Manual

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DR600 Service Manual

APC and Stationary Wave Protection Circuit
The directional coupler detects the forward and reverse directions RF signal and passes the Q103,Q104 to
convert the signal to the DC voltage which is corresponding to the forwardand reverse direction power.
After the voltage division, the forward direction DC voltage with the reverse direction voltage pass the
selection switch which is composed of D201,D202 and enter IC100(NJM2904) for buffer amplification
before being sent to the reverse phase input port of the operational amplifier of IC100(NJM2904). The
POWERCONTROL control signal form the baseband will be sent to the identical phase input port of
IC100(NJM2904)’s operational amplifier. After the operational amplification and external circuit’s function
calculation, the signal is output as a conrol signal which controls the U100 gain control port to ensure that
the actual output power remains stable when the impedance matches and to decrease the output power for
power amplifier protection when the impedance mismatches.

Temperature Detection Circuit
The continuous temperature rise can lead to a decrease of transmitting power. The temperature detection
employs IC101(DS18B20) to collect the digital temperature sample.When the temperature exceeds the
threshold value, the fan will be switched on for heat dissipation.
3.1.3 Rx Module Circuit
Figure 3-3 Receiver Module
IC6003
FS
DATAOUTB
CLK
DATAOUTA
IC6001
AD9864SY NCB
IC1000
Q1009/1011
U5002
Q2002
PD
PC
PE
PLL
PLL CONFIG
12.8MHz
BPF ADJUST
IC3000
L3006/8/9
L3000/1/2
Z3001
IC3005
L3010/11/12 Z3000
Q3001/2
U4000 AD9864
2rd LO 18MHz CLOCK
IC3003
RXVCOSELECT

Receiver Circuit
The receiver circuit includes RF Band pass filter, Low-noise amplifier, mixer, IF filter, IF amplifier and IF
processor.
The signal from the receiving port first passes the low pass filter to suppress the high frequency
interference, and passes the electrical tuning BPF to suppress the image interference and the out-band
interference.The in-band signal is sent to the low noise amplifier (IC3000) and the amplified signal passes
the electrical tuning BPF controlled by BPFADJUST to filter the out-band interference, so the effective high
frequency will be sent to the mixer(IC3005). Meanwhile, the first local oscillation passes the LPF and gets
mixed with the effective signal in IC3005 to generate the first IF signal (51.65MHz). The first IF signal
passes the crystal filter (Z3001) to suppress the out-band signal. The signal is then sent to IF amplifier
(IC6003) for amplification before being sent to the crystal filter to strenghthen the suppression of the the
adjacent channel. After being sent to the limiting amplifier composed of Q3001 and Q3002, the signal
enters AD9864 (U4000) for the second frequency mixing ,IF amplification and AD sampling. The digital IQ
signal will be finally output to the baseband for further processing.
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