Panasonic KX-G8300 Service Manual And Technical Manual page 47

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4) Duplexer and Mixer
Circuit Operation:
A circulator is used to switch the transmit and receive signals of the radar.
The RF output from the magnetron is supplied to the circulator. The power supplied to the input port 2 of
the circulator is fed to the antenna side port 3 of the circulator, it is passed to the antenna via the rotary
joint, and is radiated into space.
The RF echo signals received by the antenna are supplied to port 3 of the circulator via the rotary joint.
These signals are fed to port 1 of the circulator and then to the microwave integrated circuit (MIC).
The MIC is a superheterodyne type receiver consisting of a limiter, RF amplifier, mixer and local oscilla-
tor. The RF signals supplied via the circulator are supplied to the mixer stage via the limiter and RF
amplifier. The limiter serves to protect the receiver from excessive input signals supplied from the an-
tenna. When excessively high input signals are supplied, they are reflected by the limiter.
The mixer serves to mix the 9410 MHz received signal with the local oscillator signal contained in the
MIC, and it converts the resulting signal into a 60 MHz IF signal. This 60 MHz IF signal is sent to the IF
amplifier.
The frequency of the local oscillator is controlled by the tuning control voltage so that an optimum IF fre-
quency signal is obtained by manually adjusting the tuning knob on the display unit.
ANTENNA
Fig. 46
5) IF Amplifier (PQUP821ZA)
Circuit Operation:
The amplifier board consists of an IF amplifier (Q601, IC601), bandwidth selector circuit
(Q603,Q604,Q612), post IF amplifier, detector, STC circuit (A.C.Sea clutter), tuning indicator circuit and
tuning control circuit.
IF Amplifier Circuit
The received IF signal from the MIC (microwave integrated circuit) is amplified by about 20 dB by transis-
tor amplifier section (Q601) of the IF amplifier circuit, and is sent to IF amplifier IC601 via IFT (T601). It is
amplified by about 35 dB by IC601 and sent to the bandwidth selector circuit in the next stage via IFT
(T602).