R.L. Drake

Drake Mods - R4A

Authored by VE3EFJ

3.9 THE R4A

    Just before V6 was published, data was received regarding this receiver. Over the course of the last year there have also been requests for mods and detail on the 'A' line.

    The R4A was the companion receiver for the T4X. Functionally, there is little difference to the 'B' line. Appearance wise, it is easy to confuse the two at first glance. The R4A receiver can be looked upon as a cross between the R4B and a TR3. The R4A and R4B are very similar up to the last IF amplifier. Even the noise blanker is much the same between the two receivers. Where the major differences occur are in the AGC detector and the product detector. These areas are similar to the TR3.

    Two major differences between the A and the B receivers have been observed. First, the R4A uses bipolar transistors in the PTO and they tend to drift a bit more than the B. Second, it has been said that the A sounds even better than the B. This is highly subjective, but if it is true, the likely cause is the use of a vaccuum tube product detector in the A and germanium diodes in the B.

    I know of one chap that had a B and an A receiver. He liked the A receiver so much, he swapped the PTOs.

    Like the R4B, there are very few mods that are necessary or recommended. Like the R4B, the R4A was complete out of the box.

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