[Milsurplus] R-388 revisited

[Neil Barnett]

> Before I dive headlong into this near untouched beauty I thought I'd get 
> some advise from those much more knowledgeable that I  about these 
> receivers.  My 388 has somewhat distorted audio as if it's being over 
> driven.  I made preliminary checks of things like the filter caps and 
> all is fine there.  Is this a common problem?  I took audio off the IF 
> to be sure it wasn't coming from the audio amplifier section and the 
> distortion is still there.

The audio coming out of the detector is not necessarily distorted.
Maybe it's such high level that it's overdriving not only the receiver's
audio stage but also your outboard test amplifier.  Try knocking the
level down somewhat with a pot or 10:1 resistive voltage divider.
Other than that, the most common culprit for distorted audio in tube
radios was a leaky coupling capacitor in the audio section allowing
plate voltage from one stage to leak onto the grid of the tube in the
following stage, shifting the latter tube's bias point.

73 de Neil ZL1ANM