Icom IC-751A Instruction Manual

(2)
SIMPLE
FREQUENCY ADJUSTMENT A
very
accurate frequency
counter
is required
to align
the
frequency
of
the
IC-751A. However,
a
simple
check
may
be
performed
by
receiving radio
station
WWV,
WWVH
or
other
standard
frequency
signals.
1)
Select the AM
mode
and
GENERAL
COVERAGE
mode.
NOTE: This
adjustment
calibrates the reference
oscillator,
therefore it
is unnecessary
to
calibrate on
any other
frequency.
2)
Use the
TUNING
CONTROL
to
set the
frequency
display
to the
exact frequency
of
the
standard
frequency
station
(10.000.0MHz
for
WWV/WWVH).
Check
for
a strong
receiver
signal.
3)
Turn ON the
MARKER
SWITCH
on the
top panel.
4)
Adjust
the
MARKER
CALIBRATOR
on
the
top
panel for
zero
beat. Zero
beat exists
when
two
signals
are
on exactly
the
same
frequency
resulting
in no
audible
tone.
5)
Turn OFF
the
MARKER
SWITCH.
(3)
ELECTRONIC
KEYER
WEIGHT
CONTROL
Features designed
into
the custom
microprocessor
include
contact
debouncing, RF
immunity,
self-completing
character
generation,
dot
memory and
weight control.
The keying speed
can be varied
continuously
from
5 to
45 words
per
minute.
The
R8
WEIGHT
CONTROL
is
set
fully
counterclockwise
at the
factory
which
sets the
DOT;SPACE:DASH
ratio
at
1:1:3.
DOTS
and DASHES increase in
length if
R8 is turned
clockwise.
(4)
CW
SIDETONE
FREQUENCY
ADJUSTMENT
1
)
This control
is factory
set
for
a
700Hz
tone.
2)
Connect
a CW key
to
the KEY
JACK
on
the
rear
panel and
select
the CW mode.
(5)
SCAN SPEED
ADJUSTMENT
(6)
BFO
ADJUSTMENT
(7)
TRANSMIT
AUDIO
ADJUSTMENT
3)
Close the CW key and
adjust R374
for
a suitable
tone. Refer
to
SECTION
13-2
BOTTOM VIEW for
the
adjustment
location.
1)
Activate the
PROGRAMMED
SCAN.
Refer
to SECTION
8
for
information on the
scanning functions.
2)
Adjust R14 for
a suitable scanning
speed. Refer
to
SECTION
13-2
BOTTOM
VIEW for the adjustment
location.
1
)
Connect
a
frequency
counter
to CPI on the MAIN
unit.
Refer
to
SECTION
13-1
TOP VIEW
for the CPI
location.
MODE
FREQUENCY
(MHz)
ADJUSTMENT
RECEIVE
TRANSMIT
USB
9.01300
9.01300
C202
LSB
9.01000
9.01000 L33
CW
9.00990
NO
SIGNAL
L34
RTTY
9.008475
9.008475
L35
AM
NO
SIGNAL
9.01000
L33
FM
NO SIGNAL
NO SIGNAL
The
bass and
treble response
of your transmitted
signal may
be
altered with
the R155
adjustment
on the MAIN unit.
Refer
to
SECTION
13-1
TOP
VIEW for
the
R155 location.
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54
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Icom IC-751A Specifications

General

Brand	Icom
Model	IC-751A
Category	Transceiver
Language	English