Icom IC-751A - Page 13

®PASSBAND
TUNING CONTROL
PBT
-g>-
NOTCH
^^TX
SWITCH
JTX
®RIT/zlTX
CLEAR
SWITCH
CL
B1
This
control allows
continuous
tuning
of
the
receiver
selectivity
when using
the
SSB, CW or RTTY
mode.
Besides
reducing
inter-
ference
on the
desired
signal,
PASSBAND
TUNING
may also
improve
the receive
audio.
The
normal
position
is in
the center
(1
2
o'clock)
which
sets filter
bandwidth
at 2.3kHz
on
SSB. Refer
to
SECTION
7
-
7 for
more
information.
This
switch
turns the
variable
receive
frequency
circuit
ON
and
OFF.
When
the
circuit
is activated,
the
letters
"RIT" on
the
front
panel
illuminate
and the
amount of
shift
is
indicated.
The
amount
and
direction
of
frequency shift
is retained
in
memory
whether
the
circuit
is ON
or
OFF
until
erased
with the
RIT/^TX
CLEAR
SWITCH.
Refer
to
the
description
for the
INCREMENTAL
TUN-
ING
CONTROL
and also
SECTION
7
-
10
for
more
information.
This
switch turns
the variable
transmit
frequency
circuit
ON and
OFF.
When
the
circuit
is
activated,
the
letters
“AIX”
on
the front
panel
illuminate
and the
amount
of shift
is
indicated.
The
amount
and direction
of frequency
shift
is
retained
in memory
whether
the
circuit is ON or
OFF
until
erased with
the
RIT/idTX
CLEAR
SWITCH.
Refer
to the
description
for
the
INCREMENTAL
TUN-
ING
CONTROL and
also
SECTION
7
-
10 for more
information.
This
switch
clears the
memory which
contains the
frequency
shift
information
as set with the
INCREMENTAL
TUNING
CONTROL
and
resets the
small incremental
tuning
display
to
"0.0".
Push
the
FUNCTION
SWITCH
first, then
this switch
in
order
to add
the
shifted frequency
as
shown
on the
incremental
tuning
display
to
the
frequency
on the main
frequency
display.
The
incremental
tuning display
resets
to
"0.0".
Refer
to SECTION
7
-
10 for
more
information.
©FILTER
SWITCH
FILTER
©NOTCH
FILTER
SWITCH
NOTCH
I
@VFO
A/B
SWITCH
[A/Bl
This switch
selects a different
combination
of
the second IF
(9MHz)
filter and
the third IF
(455kHz)
filter
to vary
the
overall
selectivity
as
shown
in the following
chart.
FILTER
SWITCH
SSB
CW/RTTY
CW/RTTY
NARROW
AM
FM
OUT
2.3kHz
500Hz
500/250HZ
8kHz
15kHz
IN
2.6kHz
2.3kHz
500/250HZ
3kHz
15kHz
Refer
to SECTION 7
-
9
for more
information.
This switch
controls the notch
filter
circuit.
•
Notch
Filter OFF:
Switch
OUT
•
Notch Filter
ON: Switch
IN
This
switch
selects either VFO
A or
VFO B for
tuning
purposes.
©VFO
EQUALIZING
SWITCH
[A=B]
This
switch instantly
matches
the frequency
and
mode of
operation
of the
two VFOs.
The display
does not
change when
this
switch is
P j|
pushed,
however
confirmation
of the
equalizing
process is
possible
^
1
by
pushing
the
A/B SWITCH
to
check
the
frequency
and mode
of
the
opposite
VFO.
VFO
A
VFO
B
USB
VFO A
VFO A
,
K
USB
/
u J
/
n
n
,
ILL
1
U.
LI
LI
1
VFO A
USB
p
1.
3
S
0.0
0
1
VFO
B
1
^
VFO
B
Push
A=B
SWITCH.
USB
/
u J
7
n
n
r, ,
ILL
1
U.
LI
0
1
VFO
B
-
9
-