Icom IC-751A Service Manual page 65

TRANSMITTER ADJUSTMENT
just to
MAIN
OUTPUT 1 | © Frequency display: 14MHz REAR Connect an RF power
POWER © USB mode PANEL | meter to the ANTENNA | obtain MAX.
©@ COMP SWITCH: OFF CONNECTOR. output power.
® Apply a 1.5kHz/3mV signal from I- AF
the AG, then adjust the MIC GAIN YOLTMETERT{~7| GENERATOR
CONTROL to output 30W of power. PIN 1
2 | © FM mode 50W FRONT RF
® MIC GAIN CONTROL: MAX. CCW PANEL | POWER
CONTROL
® MIC GAIN CONTROL: MAX. CW PIN 1: AG input MAX. MAIN L2
Note: The RF POWER CONTROL PIN 7: GND output
should remain in the same PIN 5: Jumper
w g : 6: Jumper
position as in step 2 above. .
Ic* APC
1 | © Frequency display: 14MHz REAR
Connect an ammeter to 22A
MAIN R99
®@ RTTY mode PANEL | the power cable.
@ RF POWER CONTROL: MAX. CW
® Transmit mode
ALG
1 | © Frequency display: 14MHz
REAR Connect an RF power
100W MAIN R87
e RTTY mode PANEL meter to the ANTENNA
@ RF POWER CONTROL: MAX. CW CONNECTOR.
: . p
® S8 on MAIN UNIT: Switch to rear PANEL | meter to the ANTENNA
panel side. CONNECTOR.
® Transmit mode
4 | @ RF POWER CONTROL: MAX. CW Connect an oscilloscope 100% R159
@ AM mode to the ANTENNA modulation
® MIC GAIN CONTROL: (set as CONNECTOR.
MIC GAIN -@> RF PWR
or
50W RF
output power
5 | ¢ MIC GAIN CONTROL: MAX. CCW Connect an RF power 40~60W Verify
meter to the ANTENNA
CONNECTOR.
CARRIER 1 | © Frequency display: 14MHz REAR Connect an RF voltmeter | Alternately MAIN R158
SUPPRES-
© USB and LSB modes
PANEL | or spectrum analyzer to | change the
R161
SION ® COMP SWITCH: OFF the ANTENNA operating
® MIC GAIN CONTROL: MAX. CCW CONNECTOR. mode
© Transmit mode between USB
and LSB, and
adjust R158
and R161 for
MIN. output
of less than
—50aB.
2 | © COMP SWITCH: ON Less than Verify
—50dB