R.L.DRAKE R-4A, Instruction Manual

Page: 37 / 39

band tuning knob should be pointing horizontally to the left as
viewed from the front. If it is not, loosen the knob set screw
and reposition the knob.
3. Tune in a crystal calibrator signal at 3.8 mc for zero beat.
4. Set the Passband selector lever to
.4
and set the Passband tuning
knob to the center of the shortest line.
5. Attach a VTVM to the AVC test point (TP-2) and adjust the four slugs
on the rear of the passband tuner for maximum AVC voltage.
IMPORTANT - The passband tuner slugs have a considerable amount of
spring when turned and this must be taken into consideration when the
slugs are adjusted so as to obtain a true peak.
6.
7.
8.
9.
10.
11.
Set the Passband selector switch to 1.2 KC and turn off the crystal
calibrator.
Turn the Passband knob through its range while observing the pitch
of the received noise. Adjust the small screw on the rear of the
tuner until the pitch of the noise is the same at the extreme ends
of the control travel. (Pointer pointing horizontally to the left and
to the right.)
Set the Passband selector lever to the 2.4 KC position and observe
the pitch of the noise at the dots at the ends of the second line
from the bottom. The pitch should be the same at either dot.
If it is not, turn the knob to the left dot and observe the pitch.
Then rotate the control to the right until the pitch is the same.
Loosen the knob set screw and rotate the knob until it is halfway
between its position at step 9 and the right dot.
Tighten
set screw.
J.
Bias and
S-Meter Adjustment
1.
2.
3.
4.
Attach a VTVM to TP-2 and with the Preselector detuned and the
antenna disconnected, adjust the RCVR SENS control, located
on a component board directly behind
Tll ,
for - 1.3 5 volts.
Remove the VTVM and adjust the S-Meter Zero control, located on
the side of the chassis, for a reading of S-l on the S-Meter.
Rotate the R.F. Gain control fully counter clockwise and adjust the
S-Meter Cal adjustment (R40) located on the component board
mounted directly behind V5 for an S-Meter reading of 60DB over S-9.
Recheck
steps 2
and 3 with the unit sitting upright. Readjust if
necessary.
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