Icom IC-756PROII Service Manual page 24

4-3 TRANSMITTER ADJUSTMENTS
ADJUSTMENT ADJUSTMENT CONDITION
1 • Display frequency: 14.100000 MHz
IDLING
CURRENT • Mode
(for driver) • Preset R11, R18 on the PA unit to
max. CCW.
• [RF POWER]
• [TUNER]
• Transmitting (without key)
After adjustment, re-solder the lead wire (W29) on the PA board.
(for final 2 • Transmitting (without key)
amplifier)
After adjustment, re-solder the resistor (R28) on the PA board.
TX PEAK 1 • Display frequency: 14.100000 MHz
• Mode
• Set following selections, controls
and functions as :
[VOX] : OFF
PBT1 : Center ,
Filter
[RF POWER] : Max. CW
[MIC GAIN]
[TUNER]
[METER]
[MONITOR]
• Apply no audio signals to [MIC]
connector.
• Transmitting
2 • Connect an audio generator to
[MIC] connector and set as:
Frequency
Level
• Transmitting
3 • Transmitting
4 • [MIC GAIN]
• Preset L711, L712, L713 to bottom.
• Connect an audio generator to
[MIC] connector and set as:
Frequency
Level
• Transmitting
Adjustment in sequence L701, L752, L713, L711, L713, L712, L711, L713, L711, L712.
1 • Display frequency: 14.100000 MHz
TRANSMITTER
TOTAL GAIN • Mode
• [MIC GAIN]
• Connect an audio generator to
[MIC] connector and set as:
Frequency
Level
• Transmitting
MEASUREMENT
UNIT
PA
: CW (key up)
: Max. CW
: OFF
PA
MAIN-A
: USB
, [∆TX] : OFF
PBT2 : Center
: 2.4 kHz
: Center
: OFF
: METER Po
: OFF
Rear
panel
: 1.5 kHz
: 1 mVrms
: Center RF-A
: 1.5 kHz
: 10 mVrms
Rear
: USB panel
: Center
: 1.5 kHz
: 1 mVrms
4 - 4
LOCATION
Unsolder W29.
Connect an ammeter
to the unsoldering
points of W29.
Unsolder R28 (L8
side).
Connect an ammeter
to the unsoldering
points of R28.
Connect a digital
multimeter or oscillo-
scope to the check
point CP243.
Connect an RF
power meter to
[ANT1] connector.
Maximum output
Connect an RF volt- Maximum level
meter to the check
point J151.
Connect an RF
power meter to
[ANT1] connector.
ADJUSTMENT
POINT
VALUE
UNIT ADJUST
100 mA PA
500 mA PA
0.06 V MAIN-A
50 W Front [MIC GAIN]
panel
MAIN-A
power
RF-A
50 W MAIN-A
R11
R18
R247
control
L261
L701,
L711,
L712,
L713,
L752
R263