2: System Overview
PRC1099A-MS
2-7
AGC - Q4, Q5
Receive
Amplifies AGC IF gain.
Input from RX IF output.
Output to 1650 kHz IF amp,
75 MHz IF amp Mixer board.
TX IF Amp - Q3
Transmit
Amplifies 1650 kHz DSB signal
from Audio/Filter board.
Input from balanced modulator
Audio/Filter board.
Output to 1650 kHz sideband
filter.
Mixer Board
Double-Balanced
Mixer - MX1
Transmit
Converts 75 MHz IF to selected
channel frequency.
Input from 75 MHz IF filter; output
to TX 1.6 to 30 MHz amp.
1st LO: 76.597 to 105 MHz SYN1
buffer
Receive
Converts selected channel
frequency receive signal to
75 MHz IF.
Input from antenna through
Audio/Filter board; output to RX
75 MHz IF amp.
1st LO: 76.6 to 105 MHz SYN1
buffer
RX 75 MHz IF
Amp - U4
Receive
Amplifies 75 MHz IF receive
signal.
Input from double-balanced mixer
MX1.
Output to 75 MHz filter Y1.
75 MHz Crystal
Filter - Y1
Transmit
Filters 75 MHz IF signal for
transmit path.
Input from 75 MHz IF amplifier
Q11
Output to MX1 mixer.
Receive
Filters 75 MHz IF signal for
receive path.
Input from 75 MHz IF amplifier U4
Output to RX amplifier Q7.
RX 75 MHz IF
Amp - Q7
Receive
Amplifies 75 MHz IF RX signal,
controlled by AGC circuit.
Input from 75 MHz filter Y1.
Input from ALC on 1650 kHz IF
Board.
Output to RX mixer Q8.
RX Mixer - Q8
Receive
Down-converts 75 MHz IF signal
to 1650 or 1647 kHz signal.
Input from 75 MHz IF amp Q7.
2nd LO: 73.35 MHz SYNTH2
buffer Q10.
Output to 1650 kHz IF board.
TX 75 MHz IF
Amp - Q11
Transmit
Amplifies 75 MHz IF TX signal,
controlled by ALC circuit.
Input from the TX mixer U2.
Input from ALC switch Q12.
Output to the 75 MHz IF filter Y1
TX Mixer - U2
Transmit
Up-converts 1650 or 1647 kHz
signal to 75 MHz IF signal.
Input from 1650 kHz IF board.
Osc. 73.35 MHz Syn. 2 buffer.
Output to 75 MHz IF amp TX.
Table 2-1 Board Functionality (continued)
Function
Path
Description
I/O
