Transmitter Adjustments - Icom IC-7400 Service Manual

5-3 TRANSMITTER ADJUSTMENTS

ADJUSTMENT ADJUSTMENT CONDITION
IDLING 1 • Displayed freq. : 14.100000 MHz
CURRENT • Mode
• [MIC GAIN]
• [RF POWER] : Max. CW
• [TUNER]
• Preset R11, R18, R109, R204, R215
(PA unit) to max. counter clockwise.
• Transmitting
(for driver)
2 • Transmitting
3 • Transmitting
(for HF/50 MHz
band final
amplifier)
4 • Transmitting
• Displayed freq. : 144.00000 MHz
5
(for 144 MHz
• Mode
band final
• Transmitting
amplifier)
6 • Transmitting
After adjustment, disconnect the ammeter between the power supply and the transceiver.
144 M PEAK 1 • Displayed freq. :
146.00000 MHz
• Mode
• Transmitting
1 • Displayed freq. : 145.00000 MHz
TX PEAK
• Mode
• Set following controls as:
[RF POWER] : Max. CW
[MIC GAIN]
[KEY SPEED] : Center
[PITCH]
• Disconnect P1 (PA unit) from J151
(RF unit).
• Connect an audio generator to
[MIC] connector and set as:
Frequency
Level
• Transmitting
After adjustment, re-connect P1 (PA unit) to J151 (RF unit).
2 • Displayed freq. : 14.100000 MHz
• Mode
• Connect an audio generator as:
Frequency
Level
• Transmitting
3 • Transmitting
TRANSMITTER 1 • Displayed freq. : 14.100000 MHz
TOTAL GAIN • Mode
• [MIC GAIN]
• Connect an audio generator to
[MIC] connector and set as:
Frequency
Level
• Transmitting
• Mode
Ic APC 1
• Connect CP300 to GND.
• Transmitting on the maximum TX
current band.
MEASUREMENT
U N T I
PA
: USB
: Max.CCW
: OFF
: USB
Rear
panel
: RTTY
RF
: USB
: Center
: Center
: 1.5 kHz
: 1 mVrms
Rear
: USB panel
: 1.5 kHz
: 1 mVrms
Rear
: USB panel
: Center
: 1.5 kHz
: 1 mVrms
: RTTY Rear
panel
5 - 4
L O C A I T O N
Measure the driving
Connect an ammeter
current, and note it as
between the power
the "initial value."
supply and the
transceiver.
more than initial value
more than step "2"
more than step "3"
more than step "4"
more than step "5"
Connect an RF Maximum output
power meter to the
[ANT 144MHz] con-
nector.
Connect a digital Maximum output
multimeter or oscillo-
scope to the check
point J151.
Connect an RF
power meter to the
[ANT1] connector.
Max. output power
Connect an RF
power meter to
[ANT1] connector.
Connect an ammeter
between power sup-
ply and the transceiver.
ADJUSTMENT
POINT
VALUE
U N T I A D
PA
+1.5 A
+500 mA
+500 mA
R109
+500 mA
R204
+500 mA
R215
PA C202
power
RF Adjust
Level s e q u e n c e
L253, L252,
L251,
several times.
50 W Front [MIC GAIN]
panel control
MAIN L330
50 W MAIN R331
R555
23 A MAIN
J U S T
–
R11
R18
in
L272