3: Audio/Filter Board
PRC1099A-MS
3-11
3.2.4
J4 Connector
J4 connects to the Mixer and Synthesizer boards.
2
VOICE DET
Voice detect informs microprocessor of
received human speech.
3
ENM1
Enable pulse enables U7 and U9.
4
MUTE
Low going pulse from microprocessor to
disable receive audio.
5
CONTRAST
Output to Display board to set display
contrast.
6
CW KEY
A signal from outside radio to key transmitter
as well as energize CW oscillator.
7
SPARE2
Not used.
8
600 OHM RX AUDIO
Receive audio output to microprocessor.
9
SPARE1
Not used.
10
600 OHM TX AUDIO
Transmit audio input from microprocessor.
Table 3-4 J3 Connector Pin Assignments (continued)
Pin
Signal
Description
Table 3-5 J4 Connector Pin Assignments
Pin
Signal
Description
1
BITE
No connection on the Audio/Filter board.
Jumpered from the Processor board (J2 pin
1) to the Synthesizer board.
2
SQUELCH
Output to Mixer board to disable the receive
audio.
3
AME SEL
Amplitude modulation equivalent output to
Mixer board.
4
DATA
Microprocessor data output to rest of radio.
5
CLOCK
Microprocessor clock output to rest of radio.
6
ALC
Automatic level control output to Mixer board.
7
ENM6C
Output enable pulses from microprocessor to
Synthesizer board.
8
ENM6B
Output enable pulses from microprocessor to
Synthesizer board.
9
ENM6A
Output enable pulses from microprocessor to
Synthesizer board.
10
LOWPWR
Input from PA board to automatically switch
to low power, when PA board overheats.