[R-390] Silve Mica cap question

[Cecil Acuff]

I have come into this late but my experience is that molded micas are much 
more an issue than the dipped silver micas.  I don't see silver micas fail 
often..in fact I probably haven't replaced one in several years.  I know 
they go bad occasionally but not nearly as often as the molded micas.  I 
have quite a few silver NOS caps and will use them without fear.  I will 
check them at their rated voltage before installing one but usually find 
them to be fine.

Perry I would find a cap checker that checks at rated voltage.  I am partial 
to the Sencore LC53 and LC73 capacitor/inductor testers.  I'm currently 
using an LC-77 and it has become my favorite.  They show up on the auction 
site and are excellent for testing all type of caps.

I wouldn't buy NOS micas but wouldn't hesitate to pick up NOS silver micas 
for use in our old radio's....

Cecil...
----- Original Message ----- 
From: "Perry Sandeen" <sandeenpa at yahoo.com>
To: <r-390 at mailman.qth.net>
Sent: Sunday, September 14, 2008 10:46 PM
Subject: [R-390] Silve Mica cap question


Gents,

Wrote: I have had very poor results with NOS micas from a variety of sources 
that were made before 2000, so I don't buy them anymore.  <snip>

Could you please expand?

I have a bunch of  epoxy dipped silver mica’s that I’ve acquired over the 
years.  Some are probably 30+ years old and most don’t have a date stamp on 
them.  Or are you referring to NOS molded Micas?

If you are referring to the epoxy dipped SM’s, is there a simple way to test 
for leakage?  I have a Marconi LCR bridge that is SS.  Does one need a 
Sprague TO-6 or something similar with a HV leakage test?

I sure don’t want to have to replace a replacement but I also don’t want to 
throw away the SM’s I have.

Regards,

Perrier




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