DRAKE R-4A Spécifications télécharger pdf (Page 37)

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.

Tune in a crystal calibrator signal at 3.8 mc for zero beat.

Set the

Passband

selector lever to

and set the

Passband

tuning

knob to the center of the shortest line.

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.

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.

Bias and S-Meter Adjustment

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

and 3 with the unit sitting upright. Readjust if

necessary.

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DRAKE R-4A Spécifications Page 37

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