Ernie wrote:
My old receiver's IF wouldn't align and I finally traced it down to the IF
can. A grid dip meter shows the primaries and secondaries of each coil are
anywhere from 20 to 40 kc away from the design frequency (460kc). The
trimmers trim OK, but just not close to 460 kc.
I can bring each coil back to the IF frequency by soldering another small
value cap (100 pf or less) parallel to the trimmer. The capacitor sellers
have all sorts of variations and I am wondering if anyone can give me a
suggestion as to what kind would be the best to use for this application?

Silver mica. In a pinch, an NPO ceramic would probably be fine.

BUT... this happens when the capacitor inside the IF can fails. If it
failed completely, you're fine. But if it failed partially then adding the
cap will only be a temporary measure...eventually it will fail completely
and then the value will change again.

So I would suggest going into the can and clipping out the old capacitor
if you're willing to risk it, then putting a new silver mica in.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."