[R-390] audio deck saga numbers

[wli]

Well, by re-evaluating my unit after the audio deck rebuild with the previously posted small modifications.... and injecting 4uV into the antenna jack as suggested by D. Wise.... I gained 2dB improvement in the CW vs CW+mod test. This is makes more sense, since all the work was done in the audio deck. I ran a comparison with a known good audio deck, using the same tubes, and the numbers came out real close during testing with the modified deck being little better by the numbers.... just as one would expect.

Final result, this Collins is slightly better than 20:1. My Capehart is a 30:1 unit, so this one *needs work*.

In summary, any improvement was qualitative and not quantitative. Things just sound louder and clearer to me. Need to put a sweep audio thru the deck as my next move........

I did not check it on SSB yet.

Here is the list of changes:

part     original value                      new value

R612        220K ohms                   N/A  since it was removed
R615         56 ohms                                24 ohms
R101         6800 ohms                  zero ohms (shorting wire)
R102         820 ohms                        820 ohms (no change)
C609          8uFD 50v                    N/A since it was removed
Rxxx            N/A                    10M ohm from pin 1 to pin 7 of V601
C606       45-45uFD/300v                45-45uFD/350v (new)
C603      30-30-30uFD/300v          30-30-22uFD/350v (new)

Thanks

W. Li 
Mercer Island, WA