Yaesu FT-901DM Maintenance Service Manual page 83

SERVICING
5. AMGC (Automatic Mic Gain Control)
6. CARRIER FREQUENCY ADJUSTMENT
x P pELXAND HAN HAG
NB/PROC unit (PB-1703)
7. ALC LEVEL ADJUSTMENT
Set the METER switch to ALC, the MODE switch
to USB or LSB, the MIC GAIN control counter-
clockwise, and the VOX GAIN control to MOX.
If the meter reading is not fully deflected to the
right, adjustment of the ALC level control VR201
on PB-1703 will be required. Adjust VR, for a
reading of 350 (full scale) and return the VOX
GAIN control to PTT.
Tune up the transceiver on USB at 14.2 MHz. Set
VR2o2
and the
PROC LEVEL
controls
to the
center of their range. Apply a 1 kHz audio signal
to the microphone input and adjust its level to
the point where power output levels off after
reaching its maximum value; do not advance the
input level past the saturation point. Adjust VR93
so as to obtain the same power output when the
RF Processor switch is in the ON and OFF posi-
tions.
9. IF PASSBAND TUNING ADJUSTMENT
Tune the receiver to 14.2 MHz in the USB mode
and
set the WIDTH
control
to the 12 o'clock
Position. Set the RF GAIN control fully clock-
wise.
Change the MODE switch from USB to LSB. The
receiver background noise at the speaker should
not change
in pitch. If there is any difference,
adjust VR230; located adjacent to the MODE
switch below the chassis until the noise is of the
same pitch when switching between USB and
LSB.
Memory unit
|
Mode switch
Reject/Width board
(PB-1722)