The transceiver is designed with computor type
plug-in modules. These m odules are: High frequen
cy unit , High frequency IF unit, Low frequency
IF unit , Audio unit , Modulator unit , Noise blanker
unit and Power regulator unit . The VFO unit,
Crystal oscillator unit and Rectifier unit are built
into the main chassis .
( 1 ) HF UN IT
(
PB1181B)
T his mod u l e contain s the receiver RF amplifier. rece1\'er
1st mixer. transmitter 2 nd mixer and heterodyne oscil
l ator circuit. The signal from the anten n a coil is fed
to the gate of QI ( field effect transistor
3 SK40M)
t h rough terminal
8
of the modu le.
The AGC ( au tomatic gain con tro l ) vol tage which is
obtained from the low freq u en cy I F u nit. is applied
to the gate circuit of Ql from pin
9
to control the
gain of t his stage. A manual RF gain con t ro l on thl'
front panel is con nected to the sou rce o f Q J t h rough
pin
10.
Signal output from the QI is then cou pled to the
receiver
1 st
mixer Q
2
.
2SK 1 9GR
where t h e in coming
signal is mixed with a signal from the heterodyne
oscillator
Q1.
2SC3 72Y
through the
buffl'r
stage
l�fl.
2SC3 73.
The product of the first mixer is applied
through pin 1 7 to the high frequency IF unit.
Transmitter signal is fed to the base of transmitter
2nd mixer Q3 ,
2SC784R
from pin 1 3 . The signal
from the heterodyne oscillator is applied to the
emitter of the mixer Q3 , through the buffer stage
Q4,
2SC3 72Y.
This converts the high frequency IF
signal to the desired transmitting frequency . This
transmitting signal is fed to T l 02 through pin 1 1 .
The gate circuit of the receiver mixer Q2 is discon
nected in transmit by diode switch to avoid the
lowering the Q2 of the circuit . Crystal sockets and
all coils are mounted on the main chassis.
( 2)
H I G H F REQUENCY IF UNIT
(
PB11808)
The module contains the transmitter first mixer Q I,
2SC3 72Y,
the receiver second mixer Q2 ,
3SK40M,
and the 5520 to 6020 KHz bandpass network. The
signal from the receiver 1 st mixer is fed to the gate
VR1 Q2
Q3
QI
Q.
Q5
High Frequency Module
(PB-1181)
of the mixer through the bandpass network L 1 , L2 ,
and L3 , from pin 1 5. VFO voltage is also applied to
the 2nd gate of Q2 from pin 1 1 . The signal is con
verted to 3 · 1 80 KHz low frequency IF and fed to
the following stage through pin 3 an output trans
former T l l 2A. On transmit , the 3 1 80 KHz signal is
fed to the base of the mixer, from pin 5. A 1 4 MHz
trap coil Tl 1 3 is connected to the base circuit o f
Q l . The VFO signal i s fed t o the emitter o f the Q l
which produces the 5520 t o 6020 KHz high fre
quency IF signal. This signal is fed to the following
stage from pin 1 6 through the bandpass network.
High Frequency IF M odule
(PB-1180)
S:S2
2oB
6:02
F1MH,!
BA N D PASS NETWORK C H A R A CTER ISTICS
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