Icom IC-502A Instruction Manual page 20

Coils Adjustment
Connect the wattmeter to the external antenna socket, and set the transmit/receive frequency
at "50.5Н2".
With the MODE switch turned to "CW-T", connect a key to the key jack and hold the key
down, connect the RF volt-meter probe to Q13 base and adjust the cores of L15 — L19
alternately for a maximum voltmeter reading.
Driving and Final Stage Adjustment |
Make sure that the power voltage is 13.8V, under the same condition as in 3, then fully turn
the R73 rotor toward ground and adjust L20, L21, C131 and C133 so that the watt meter
indicates maximum (over 3W). |
After this adjustment, adjust R73 so that the wattmeter indicates 3W.
Set multimeter to 1 volt range and connect to check point J12.
Readjust L15 — L19 cores for maximum indication.
RF Meter Adjustment
Move D22 with respect to L24(coupling) so that the meter indicates about 90% of full scale
when the output is 3W at the completion of adjustment 4.
Carrier Frequency Adjustment
In the receive condition, connect the frequency counter to the R51 check-point, and adjust
C71 so that the frequency becomes 13.997mHz. At this time, make sure that if the MODE
switch is turned to *CW-T", the frequency shifts about 1KHz upward. Then turn the MODE
switch to *REC" and connect the AF oscillator to Pin 6 of J13.
Ground microphone connector pin No.2 for SSB transmission, and set the AF oscillator
oscillation frequency at 1.5KHz, and. adjust the ouput level so that transmission output
is 2.5W. Keeping this output level unchanged, alternately change the audio oscillator fre-
quency from 300Hz to 3KHz, and fine adjust C71 to equalize the transmission outputs.
Mic Gain Adjustment
Connect the AF oscillator between microphone connector pins No.1 and No.4 (toward
ground), and set its frequency at 1.5KHz, and output level at 6mV.
Ground pin No.2 and connect the AF millivoltmeter (300mV range) to the R24 check point
and adjust R17 so that the meter reads 150mV.
RECEIVING SECTION ADJUSTMENT
1. Measuring Instruments for Adjustment
* Standard signal generator (for SOMHz band)
* AF millivoltmeter
* Multimeter
Sensitivity Adjustment