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Mica Values for Philcos.
Frank
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#1

03-23-2006, 01:38 PM
Philco used some mica capacitors with values that are not available today, or might be hard to get.

How far off of the values specified in the schematic and parts list can you go before performance is affected?

For example, in the RF deck of a 37-116, there are 40 pf, 25 pf. My new mica caps are off by 1 pf (39 vs 40, 24 vs 25), and I would assume that is not worth worring about, but I could be wrong about this assumption.

How far off can you substitute a value before you affect performance negatively?

Frank
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Chuck Schwark
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#2

03-23-2006, 02:02 PM
Mica's from that era are going to be rated for 10% at best, so you're probably ok being only 1 pF. off on each value. Your subs translate to 2.5% for the 40 pF. and 3.5% for the 25 pF. cap.

Slight wiring differences on the production line would be at least a pF or two due to lead dress anyway.
Chuck Schwark,
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William
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#3

02-05-2007, 02:43 PM
You could avoid this problem by purchasing the exact values of these capacitors. http://www.justradios.com has these capacitors.
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  1. The PHILCO Phorum
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