Yaesu FT-901DM Maintenance Service Manual page 86

(6)
NOTE
Rotate the PLATE tuning control aud ob-
serve the point of minimum current ("dip")
If the dip is not prominent
LOADING control slightly to get a better
dip. As the PLATE coutrol is rotated the
meter should rise equally and smoothly on
reduce the
either side of the dip.
Determine which side of the dip rises ab-
ruptly. Set the PLATE control slightly to
this side of the dip, keep the meter reading
below 100 mA
Using a nonmetallic tuning wand, rotate the
neutralization capacitor shaft very slightly
in the direction which reduces the current
on the meter. Repeat steps 6 and 7 until
the meter mooth
indicates a and equal
rise on either side of the dip.
The final amplifier compartment cover
to supply the RF
shielding required during the neutrali-
zation procedure
must be in place
3-31
SERVICI
ALIGNMENT OF TRANSMITTER MIXER/
DRIVER
AND RECEIVER FRONT END
STAGE
(1)
(2)
(4)
(6)
(9)
Connect a dummy load/wattmeter to the
rear panel ANT jack.
Set the RF/AF gain controls fully clockwise,
set the MODE switch to FSK, and set TC2s06
to the 1/3 capacitance setting, as shown in
Fig.1 .
Set the BAND switch to 10D, set the main
tuning dial for a reading of 30.000 MHz, and
set the PRESELECT control to the upper end
of the 10 meter band (fully clockwise). Set
the LOAD control to 3, and dip the PLATE
CONTROL while tuning,
Set the CARR control to the 12 o'clock
position. Set the VOX GAIN control to MOX
(for not more than 10 seonds), and carefully
adjust T2 and T3 for maximum IC reading on
the meter, Be sure that the bonding agent has
been removed before you adjust the cores.
While receiving, set the MARKER switch ON,
and tune to thecalibrator signal. Adjust T,
for maximum S-meter deflection.
Now set the BAND switch to 10A, set the
VFO for a display frequency of 28.000 MHz,
and peak the PRESELECT control formaxi-
mum PO while Dip the PLATE
control for minimum IC indication. Now set
the VOX GAIN switch to MOX, and adjust
TC2s06 maximum IC
meter (FSK mode, still).
Set the MARKER switch ON, and tune to the
calibrator signal. Peak TC2306 for maximum
tuning
indication on the
S-meter deflection
As there may be some interaction of adjust-
ments, please repeat steps (3) through (7).
Adjust the final amplifier
as described on page3-30.
neutralization,
(10) Again repeat steps (3) through (8).
(11) Now you are ready to align the other bands.
Set the BAND switch to 15, set the main
tuning dial for a reading of 21.000 MHz, and
set the PRESELECT control at 8.6 on its
scale. Dip the PLATE control for minimum
IC indication while tuning. Set the VOX
GAIN control to MOX, and adjust TC260s