[R-390] R-392

[James A. (Andy) Moorer]

The cathode follower for the IF output on the R-392 is very poorly designed. 
The waveform is essentially saturated on one side - it is quite ugly and has 
lots of harmonics. This waveform is not used internally - it is only for 
external SSB converters. It does tolerably well for that. Unless you plan to 
use your IF output for, say, a Sherwood detector, just ignore it. If you 
have to have a pretty sinusoid, you will have to redesign that stage, 
probably using transistors instead of the tube. I haven't tried to do this 
yet, but it looks straightforward (if you have done circuit design before).

James A. (Andy) Moorer
www.jamminpower.com



----- Original Message ----- 
>
> My first question came up while checking the IF alignment.  I had a scope 
> looking into the IF output cathode follower while doing the alignment.  I 
> noticed the carrier waveform was a perfect sinewave until the input signal 
> was increased and then the bottoms of the waveform started to flatten out 
> and ultimately looked like the output of a halfwave rectifier.  Checking 
> the wave form ay the plate of the AGC IF tube, showed a perfect sinewave, 
> right at the point it feeds the grid of the cathode follower as well as 
> the two AGC rectifiers.  After alignment the signal level at the ant 
> connecter had to be less than 4uv to have the signal "look normal".  The 
> AGC action seems normal, as at a signal input level of 10K uv the audio 
> product sounded good with the RF Gain control fully clockwise.  Can any 
> one give me any idea if this is normal or if there is a trouble in the 
> receiver that I have not found?
>