[R-390] Re chirping CW and low audio plus strange PTO problem.

[Forrest Myers]

Hello All,
 Found the problem causing the low audio in my Capehart SN 557. It was C537
that changed from a capacitor to a 33k resistor. It was in the cathode
circuit of the limiter. I didn't have a direct replacement for it so put in
one, temporarily, about ten times larger than the original 1800pf. Audio is
great and it seems to have helped the CW chirp too, don't ask me how. Have
ordered replacement capacitor of the proper size, actually a 1000 pf and an
850 pf which will be paralleled.

 Now, I have a strange problem with the PTO. If I tune up from 0 to 1000, it
is very linear, within a couple hundred hertz all the way. If I tune down
from 1000 to 0, it is very linear, within a couple hundred hertz except at
100khz where it is suddenly about a kHz off. Going on down to 0 it is back
on. If I approach the 100khz mark from about 10 kHz below, it's right on the
money. If I approach it from about 10 kHz above, it's about a kHz off, low.
Scratching my head for a while, I figure there must be some mechanical
problem inside the PTO but can't imagine what it is unless the core is
dragging on the coil and causing it to move at around the 100 kHz mark.

 There is no play in the gear train or the PTO shaft coupling.  When tuning
at the 100 kHz mark, any slight movement of the tuning knob will cause a
change in the frequency of the PTO.

 Any ideas? Should I just live with it?

Forrest Myers
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