[Boatanchors] Molded mica capacitors

[Glenn Little WB4UIV]

I have a number of new old stock molded mica capacitors.

Some observations:

1. All that I have checked are slightly low in value.

I think that this may be the way that the capacitor is packaged. When I 
opened one up, I find that the molding material appears to be loose 
around the mica plates. If this was tight when made and loose now, the 
plates would not be compressed as tightly now as when new. This would 
account for a possible slight shift in capacitance.

2. The pink/red colored package appears to identify silvered plates.

The tan colored package appears to identify aluminum plates separated by 
mica.

Are these just isolated observations? or, do these capacitors shift 
lower in capacitance as they age? Does the color of the package tell 
what is inside? Many years ago I was told that the pink/red case did 
indicate silver mica and the tan case indicated a paper capacitor. The 
sample that I disassembled seems to verify that pink/red case does 
indicate a silver mica capacitor. I did not observe a paper dielectric 
capacitor in this form factor, but, see an aluminum mica capacitor in 
the tan case.

Any comments on these limited observations??


Thanks

73

Glenn

WB4UIV




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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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