Eddy -
Very nice! Glad it went well, and we can all learn. I have seen
problems with the 'Dur-Mica' (brown epoxy 'dog-bone') caps. The
slivering 'migrates' onto the ends of the mica sheets and can form
shorts. This usually show up in caps with higher DC voltages on them,
I've never seen it in a PTO. Certainly seems that in your case you just
had some crumbly solder. Only took 50 years for it to show up!! :-)
Thanks for reporting back and added to the knowledge base!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-B, C-Line&
TR-4/C Service Supplement CDs
<www.k4oah.com>
Edward Swynar wrote:
different wires& parts of the PTO---but when I applied even the gentlest of
pressure on one side only of C89---a 3000-pfd. maroon-coloured silver mica
cap in the oscillator tank---the exact same warbble& instability of before
started anew! I then pressed the other side of this same capacitor, and the
signal stabilized.
Hmmmm...sounded like a bad / "aged" solder joint of sorts to me, so I
applied heat to both points on the board contacting the capacitor's leads,
causing the solder therein to re-flow. I then attempted to again induce the
instability of before, but could only make the PTO frequency change slightly
in frequency, much as was done before by applying pressure to the other
side...
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