The output of the 10V Regulator is connected directly to the equipment ON lamp (Control
Module), Squelch IF Module, Noise Squelch Module, and TX Low Power AF Module and via
relay contact Si to the remainder of the RX modules.
Operating the Press-to-Talk switch energises R LS/2 and Si changes over to switch off all RX
Modules except for the Squelch
IF,
Noise Squelch and the AF Amplifier. The Oscillator (TX part),
TX Multiplier, PA Module (TR1 and TR2) and the Control Module TX lamp are switched on,
RX Noise Squelch and AF Amplifier are inhibited and the equipment is in the transmit condition.
MODULE DESCRIPTIONS
Receiver RF Unit (1)
The RF signal at the antenna is fed to pin 7 of the RF Unit (1) via the antenna filter and de-
energised 12R LS/2. The tuned circuit L1,C6 couples this received signal to the source of the RF
amplifier lATR2 via pin 3 of the 1st RF amplifier sub-module. AGC is applied to 1ATR2 via the
NPN input stage lATR1 and Li.
The amplified drain output of 1ATR2 at pin 1 is mutually coupled via L2, L3 to pin 2 of the
2nd RF amplifier sub-module
(1B),
and hence to gate G1 of the dual-gate MOSFET 1BTR1. AGC
is applied to gate G2, and the amplified drain output appears at pin 4. The signal is then mutually
coupled via L4,L5, C4,L6 and L7 to the input of the mixer sub-module (1C).
Amplified RF is applied to G1 of the dual-gate MOSFET ICTR1, while RX multiplier output
is applied via L8 to G2. The resultant 10,7 MHz signal appearing at the mixer drain is passed to the
10,7 MHz filter FL1. The use of field-effect transistors, together with tuned circuits L1—L7, ensures
a high degree of selectivity, while bandwidth and gain are maintained at a substantially constant
level by the use of mixed interstage coupling.
3.4
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