DRAKE R-4A Spécifications télécharger pdf (Page 17)

Operation of NOTCH control

The notch control on the R-4A consists of a permeability-tuned T-notch

filter in the 50 KC I.

This filter is capable of producing a deep notch

which can be tuned across the receiver’s I. F. for the elimination of

interfering carriers in all modes of operation.

In order to obtain optimum results using this control, it is first necessary

to set the “notch adjust” control located on the side of the chassis as

de scribed here.

Preset R-4A controls as follows:

FUNCTION

-- Cal

PASSBAND

-- Selector 2.4 or 4.8, Knob upper or lower

BAND

-- 3.5 MC

XTALS

-- NORM

R.F.

GAIN

-- Fully clockwise

A.F. GAIN

-- Comfortable level

SSB/CW-AM

-- Fast AVC

NOTCH

-- Off

With the main tuning knob, tune in the crystal calibrator for low

pitched audio note and peak the preselector for maximum S-Meter

reading.

Advance the Notch control until some reduction in S-meter reading

is observed.

Adjust Notch Adjust (located on right side of chassis) for further

attenuation.

Alternately adjust Notch and Notch Adjust for minimum S-meter

reading.

This is the optimum setting for notching and further ad-

justment should rarely be necessary.

In order to eliminate an unwanted carrier on any mode of operation,

tune the Notch control across the

Passband

of the receiver until the

carrier drops into the notch and is thus eliminated.

Note that it is just

as easy to notch out the desired carrier so a little practice will be nec-

essary to enable the operator to use the control most effectively.

Rotation of the Notch control is in the same direction from center as

Pa ssband control.

That is, if

Passband

is set to the left side (lower

sideband) then heterodynes will be removed with the Notch control set

to left of center.

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DRAKE R-4A Spécifications Page 17

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