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©POWER
SWITCH
ON
OFF
This
is
a
push-lock switch
which
controls the input
DC
power
to
the
IC-751A.
When
the
IC-PS30
AC
power
supply
is
used, the
switch
also acts as
the
AC
power
supply
switch.
Power
is
supplied to
the
transceiver
when
the switch
is
pushed
IN
and
locked.
Power
to
all
circuits
is
cut (except
to the
PA
unit
when
using
a
DC
power
supply)
when
the switch
is
pushed
again
and
released.
©AUTOMATIC
GAIN
CONTROL
SWITCH
[AGC]
AGC
©METER
SWITCH
METER
COMP
©TRANSMIT/RECEIVE
(T/R)
SWITCH
TRANSMIT
RECEIVE
This switch changes the
time constant
of the
AGC
circuit.
In
the
SLOW
position,
the
AGC
voltage
releases
slowly
for
SSB
reception.
In
the
FAST
position,
the
AGC
voltage
releases
quickly
suitable for
receiving
CW
signals
or
signals
with
rapid fading.
In
the
OFF
position,
the
AGC
circuit
and
S-meter
are disabled.
Also, the
AGC
circuit
does not
actuate
in
the
FM
mode.
In
the transmit
mode,
the front panel
meter
has
six
functions.
Vc
Indicates
the
collector voltage
of the
final
transistors.
Ic
Indicates
the
collector
current of the
final transistors.
COMP
Indicates
the
compression
level
when
the speech
compressor
Is
in
use.
ALC
Indicates
the
ALC
level.
The
ALC
circuit
begins to
function
when
the
RF
output
power
reaches
a
preset
level.
Po
Indicates
the
approximate output power.
SWR
Indicates
the
SWR
of the
antenna system
after
the
meter
is
referenced
at
"SET"
while the
Po meter
function
is
selected.
This switch
is
for
manually changing between
transmit
and
receive.
Set the switch to
RECEIVE
(down)
to place the
IC-751A
in
the
receive
mode.
Move
the switch to
TRANSMIT
(up)
to
change
to
the transmit
mode.
When
using the
PTT SWITCH
on
the micro-
phone
or
VOX
operation, the
T/R
SWITCH
must
be
at
RECEIVE.
)MIC
CONNECTOR
©MIC
INPUT
@+8V
DC OUTPUT
©FREQ
UP/DOWN
©PHONES
JACK
Connect
a
suitable
microphone
to
this
connector.
The
supplied
HM-36
hand microphone
or the optional
SM-10
desk
microphone
may
be
used.
When
using other
microphones,
refer
to the
diagram
in
SECTION
4
-4.
©AF
OUTPUT
©GND
(microphone ground)
©GND
(PTT
ground)
-(Dptt
(FRONT
VIEW)
This jack accepts
a
standard 1/4 inch plug
from headphones
with
an
impedance
of
4
~
16 ohms.
Stereo
headphones
may
be used
without
modification.
@
AF GAIN
CONTROL
AF
GAIN
RF GAIN
Increases
the
audio
level.
This control
varies
the audio
output
level
in
the
receive
mode.
Clockwise
rotation increases
the
level.
-
5
-
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