[R-390] Shifty 17 MC osc report and survey please

[Conard Murray]

Hey gang,
I have seen parts of my R-390A this weekend  I didn't plan on seeing for a
long time.
It was a positive experience though and I managed to get the symptoms under
control and maybe most of the problem taken care of. I still don't have a
good explanation of what was happening.
Pulling the RF deck revealed C275 (150V bypass) to be a BBOD with several
cracks and quite a bit of leakage. I replaced it with a .033 uF mylar and
added a 5000 pf mica across the mylar. I also replaced C326 with a mica cap
since I was in the neighborhood. Everything else was fine. Oh, I also
replaced the two .1 uF BBODs while there.
After replacing the RF deck, I found the pull to be about half of what it
was previously.  Adjusting T207 slightly off resonance got rid of the
remaining chirp without reducing sensitivity more than a negligible amount.
Before replacing the two caps, I couldn't eliminate the chirp by detuning
T207 without almost killing the sensitivity.
So, what of the survey? Tune in a strong local AMBC station, flip on the
BFO, AGC on fast  and then swap between AGC and MGC. Notice if there is any
change in pitch. A low tone makes it easier to detect a shift. You can also
listen to the 17 MC oscillator in another receiver. Please drop me a note
and let me know the results.
Thanks,
Conard, WS4S






-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.371 / Virus Database: 267.13.13/197 - Release Date: 12/9/2005