Icom IC-751A Instruction Manual page 36

SECTION 7 FUNCTIONS OPERATION
7 -1 VOX OPERATION
1) Set controls.
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GAIN-VOX-DELAY
NB LEVEL
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KEY SPEED FULL OFF
2) ~et the T/R SWITCH in the receive position.
3) Adjust VOX GAIN CONTROL.
4)
Adjust VOX DELAY CONTROL.
5) Adjust ANTI-VOX CONTROL.
7-2 SPEECH COMPRESSOR
OPERATION
1) Set METER SWITCH to "COMP" position.
METER
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S W R ~
2) Switch to transmit and speak into the mie.
3) Adjust the MIC GAIN CONTROL.
4) NOTE:
Misadjustment of the speech com-
pressor may cause interference to
other stations.
The IC-751A has a built-in VOX (voice-operated relay) circuit which
allows automatic T /R switching by using the operator's speech
modulation.
1) Set the VOX GAIN, VOX DELAY and MIC GAIN as shown in
the table.
SWITCH/CONTROL
POSITION
VOX SWITCH ON (IN)
-
VOX GAIN
FULLY COUNTERCLOCKWISE
VOX DELAY
12 O'CLOCK
MIC GAIN
12 O'CLOCK
2) Set the T/R SWITCH in the receive position. lt is not necessary
to push the PTT SWITCH on the microphone.
3) Rotate the VOX GAIN CONTROL clockwise while speaking into
the microphone until the T/R switching circuit activates. Stop
adjusting the contrai once the circuit has activated.
4) The VOX DELAY CONTROL varies the amount of delay after
your speaking stops before the transceiver changes back to the
receive mode. Rotate this contrai counterclockwise to reduce
the time delay. Set it to allow for short pauses in normal speech
without the IC-751A changing to receive.
5) Rotate the ANTI-VOX CONTROL on the top panel clockwise
while receiving a signal until the audio from the speaker no longer
activâtes the VOX circuit. Refer to SECTION
3 -
3 for the con-
trai location.
The IC-751A has a low distortion, RF speech compressor circuit
which provides greater talk power by improving the intelligibility
of the transmitted signal over long distances.
1) Set the switches and contrais as shown in the table.
SWITCH/CONTROL POSITION
MIC GAIN CENTER (12 O'CLOCK)
RF POWER
MAXIMUM COUNTERCLOCKWISE
COMP ON (IN)
METER COMP
2) Switch to transmit and turn the RF POWER CONTROL clock-
wise while speaking into the microphone until the desired RF
"PEAK" output of between approximately 10 watts and 100
watts is obtained.
3) Adjust the MIC GAIN CONTROL for a reading of between 10dB
and 20dB on the COMPRESSOR (COMP) scale.
4) For the best transmit audio, leave the compressor OFF, or use a
low mie gain setting with the compressor ON. However, when in
contact with DX stations, or under weak signal conditions, the
compressor will definitely improve the readability of your signal
when it is turned on and adjusted correctly.
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