Icom IC-751A Instruction Manual page 58

(2) SIMPLE FREOUENCY ADJUSTMENT
NOTE: This adjustment calibrates the reference
· oscillator, therefore
it
is unnecessary .to
calibrate on any other frequency.
(3) ELECTRONIC KEYER WEIGHT
CONTROL
(4) CW SIDETONE FREQUENCY
ADJUSTMENT
(5) SCAN SPEED ADJUSTMENT
(6) BFO ADJUSTMENT
(7) TRANSMIT AUDIO ADJUSTMENT
Avery 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
signais.
1) Select the AM mode and GENERAL COVE RAGE mode.
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 signais are on exactly the same
frequency resulting in no audible tone.
5) Turn OFF the MARKER SWITCH.
Features designed into the custom microprocessor include contact
debouncing, RF immunity, self-completing character generation, dot
memory and weight contrai.
The keying speed can be varied continu<;>Usly from 5 to 45 words per
minute.
The RB WEIGHT CONTROL is set fully counterclockwise at the
factory which sets the DOT:SPACE:DASH ratio at l:1 :3. DOTS
and DASHES increase in length if R8 is turned clockwise.
1) This contrai 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.
3) Close the CW key and adjust R374 for a suitable tone. Refer to
SECTION 13 -
2
BOTTOM VI EW for the adjustment location.
1) Activate the PROGRAMMED SCAN. Refer to SECTION 8 for
information on the scanning functions.
2)
Adjust
R
14 for a suitable scanning speed. Refer to SECTION
13 -
2
BOTTOM VIEW for the adjustment location.
1) Connecta frequency counter to CP1 on the MAIN unit. Refer to
SECTION 13 - 1 TOP VIEW for the CP1 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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