Section 7 Functions Operation; Vox Operation; Speech Compressor Operation - Icom ic-751a Instruction Manual

SECTION
7
FUNCTIONS OPERATION
7
- 1
VOX
OPERATION
1
)
Set controls.
VOX
a
GAIN— vox—
DELAY
COMP
KEY SPEED FULL
NB WIDE
NB
LEVEL
OFF
2)
Set the
T/R
SWITCH
in
the
receive position.
3)
Adjust
VOX
GAIN CONTROL.
4)
Adjust
VOX DELAY
CONTROL.
5)
Adjust
ANTI-VOX CONTROL.
The
IC-751
A
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.
It 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 control
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
control counterclockwise to reduce
the time delay. Set
it
to allow for short pauses
in
normal speech
without the IC-751
A
changing
to receive.
5)
Rotate
the
ANTI-VOX
CONTROL
on
the top pane! clockwise
while
receiving a signal until
the audio from the speaker no
longer
activates the
VOX
circuit.
Refer to
SECTION
3
-
3
for
the con-
trol
location.
7-2
SPEECH
COMPRESSOR
OPERATION
The
IC-751
A
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
METER SWITCH
to
"COMP"
position.
METER
2)
Switch
to
transmit and speak
into
the mic.
1
)
Set the switches
and
controls
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.
3)
Adjust the
MIC GAIN
CONTROL
for
a
reading of
between
lOdB
and
20dB
on
the
COMPRESSOR
(COMP)
scale.
4)
NOTE:
Misadjustment of the speech
com-
pressor
may
cause interference
to
other
stations.
4)
For the best transmit audio, leave
the compressor
OFF,
or use
a
low mic
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.
-
32
-