[Boatanchors] [Milsurplus] Micamold Recovery
David Stinson
arc5 at ix.netcom.com
Wed Jun 4 15:00:28 EDT 2014
Thank you for all the input. I do understand the
"conventional wisdom" concerning MicaMolds,
but I'm not convinced just yet.
Here's why: These caps were all produced about
70 years ago and have been taking-up water at about
the same rate. They have been aging as a group.
Capacitors or coconuts- age a group of things
produced at about the same time and they'll
all be in about the same shape.
We got them over the last 20 of those years.
Many of them have taken-up water (as would be
expected) and test "bad."
We've had to change them, leading us to curse them
and just change them all- it's only human nature.
But, as far as I know, no one has tried to drive the
water out, re-seal them and see if they can make another
50 years (or better, since we have better stuff to seal them).
I like the way they look and I like the possibility of
"original replacements." Got nothing to lose but a little
time and effort. So here's what I plan to do:
Coat the "dried-out" caps with varnish or poly..
anyone know which is a better water barrier?
Then build a low-freq oscillator using all of this
handful of caps, plug it in and leave it running
for a loooooong time. Like two years.
See what the "mean time between failures"
really is. If they stay in service with no failures
for a year or two (which passes quickly at our age)
or if they pop like popcorn after a week,
I'll let ya know.
73 DE Dave AB5S
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