Transmitter Adjustments - Icom IC-756PRO Service Manual

4-4 TRANSMITTER ADJUSTMENTS

ADJUSTMENT ADJUSTMENT CONDITION
IDLING 1 • Display frequency: 14.100000 MHz
CURRENT • Mode
• Preset R11, R18 on the PA unit to
(for driver)
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
• [RF POWER]
• 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 • Transmitting
TRANSMITTER 1 • Display frequency: 14.100000 MHz
• Mode
TOTAL GAIN
• [MIC GAIN]
• Connect an audio generator to
[MIC] connector and set as:
Frequency
Level
• Transmitting
Ic APC 1 • Display frequency: 3.550000 MHz
• Mode
• Connect CP501 to GND.
• Transmitting
1 • Display frequency: 14.100000 MHz
HF BANDS
OUTPUT • Mode
POWER • [RF POWER]
• [TUNER]
• Transmitting
1 • Display frequency: 51.000000 MHz
50 MHz BAND
OUTPUT • Mode
POWER • [RF POWER]
• [TUNER]
• Transmitting
AM 1 • Display frequency: 29.60000 MHz
• Mode
CARRIER
• [RF POWER]
• [MIC GAIN]
• Apply no audio signals to [MIC]
connector.
• Transmitting
MEASUREMENT
UNIT
PA
: CW (key up)
: Max. CW
: OFF
PA
MAIN
: USB
: Max. CW
Rear
panel
: 1.5 kHz
: 1 mVrms
RF
Rear
: USB panel
: Center
: 1.5 kHz
: 1 mVrms
Rear
: RTTY panel
Rear
: RTTY panel
: Max. CW
: OFF
Rear
: RTTY panel
: Max. CW
: OFF
MAIN
: AM
: Max. CW
: Center
4 - 8
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 check point
CP243.
Connect an RF
power meter to
[ANT1] connector.
Maximum output
Connect an RF volt- Maximum leve
meter to check point
J151.
Connect an RF
power meter to
[ANT1] connector.
Connect an ammeter
between power sup-
ply and the IC-
756PRO.
Connect an RF
power meter to
[ANT1] connector.
Connect an RF
power meter to
[ANT1] connector.
Connect an RF
power meter to
[ANT1] connector.
ADJUSTMENT
POINT
VALUE
UNIT ADJUST
100 mA PA
500 mA PA
0.13 V MAIN
50 W Front [MIC GAIN]
panel
MAIN
power
RF
50 W MAIN
23 A MAIN
100 W MAIN
100 W MAIN
40 W MAIN
R11
R18
R247
control
L261
L752
R263
R545
R507
R509
R510