Icom IC-720A Instruction Manual page 37

(с) Performing the adjustments shown іп (b) will affect
the adjustment done in (a). Repeat adjustments in (a)
and (b) until no difference is present.
(d) Change the MODE to LSB and adjust L30 the same as
the adjustments done in (a), (b) and (c) using L30.
(Refer to 9 - 2 - 1 on page 31.)
9-3-5 SPEECH PROCESSOR ADJUSTMENT
Place the set in transmit in USB at 14МН2 and turn the
RF POWER control fully clockwise and click OFF (COMP
OFF), and the MIC GAIN control іп the center (12 o'clock)
position. Connect the AF oscillator across Pin 1 (input)
and Pin 7 (ground), of the mic connector.
(a) Set the frequency of the AF oscillator to 270Hz and
the output at a level that gives approximately 20 watts
output on the wattmeter. Adjust R13 in the IF unit so
that both USB and LSB give equal output power.
(Refer to 9 - 2 - 2 on page 32.)
(b) Set the frequency of the AF oscillator to 1500Hz and
the output at a level that gives approximately 20 watts
output on the wattmeter. Set the RF POWER control
to MAX position (click ON), and reduce the output
level of the AF oscillator 20dB (The output voltage is
one tenth of the previous one.).
Adjust R35 in the IF unit to obtain 20 watts output on
the wattmeter.
IF unit
R35
Adjust for speech processor
+
= R98
=
Wav
поп Adjust for AM modulation
а, е
5222271
9-3-6 АМ MODULATION ADJUSTMENT
Place the set in transmit in AM at 14MHz and turn the RF
POWER control fully clockwise and click OFF (COMP
OFF), and the MIC GAIN control in the center (12 o'clock)
position. Connect the AF oscillator across Pin 1 (input)
and Pin 7 (ground), of the mic connector.
Set the frequency of the AF oscillator to 1500Hz and the
output at 100 millivolts.
Connect an oscilloscope to monitor RF output.
Adjust R98 in the IF unit for 100% modulation.
9-3-7 ІС METER ADJUSTMENT
Connect a key to the key jack on the rear panel. Place the
set in the transmit mode іп CW at 14MHz band, and turf
the RF POWER control fully counterclockwise.
Adjust R70 in the MAIN unit for a current reading of
10A.
5.
R76 Adjust for 0.6А
R71 Adjust for overcurrent APC
кат
es ar
R70
Adjust for 10А
52 (METER switch)
Set to Ic position
9-3-8 OVERCURRENT APC ADJUSTMENT
Place the set in the transmit mode in RTTY, and turn the
RF POWER control fully clockwise. Find the band with
the greatest Ic.
Adjust R71 in the MAIN unit until the point that the out-
put power begins to drop. Back off R71 slightly.
9-3-9 SWR METER ADJUSTMENT
Place the set in transmit mode in RTTY, at 14MHz and turn
the RF POWER control fully clockwise.
Set the METER SELECT switch, the METER switch and
the SWR switch for SWR reading.
(Refer to 5 - 7 - 2 on page 20.)
Adjust C7 in the SWR unit for minimum SWR reading with
a 50 ohm dummy load (or wattmeter).
C7
Adjust for SWR null