[R-390] Lightning crashes in audio

[Stan Gammons]

Hi Tisha,

Thanks for your reply and all of the other replies on this topic.

Having a few health issues at the moment, not COVID.   When I get better 
I'll see if I can figure out what is causing the problem and report back 
on what I find.


73

Stan
KM4HQE


On 8/17/20 11:46 PM, Tisha Hayes wrote:
> Mica cap failures have been understood for about sixty years when there
> were unexplained failures in high-reliability applications (subsea
> communications cable amplifiers). There are a variety of failure
> mechanisms, including;
>
> High voltage transients (sometime in the life of the mica cap). This blows
> a tiny little puncture through the mica laminates and eventually---
>
> Silver-ions migrate through this gap
> Carbon tracking from contaminants
>
> Because it is not a constant failure the capacitor gets noisy as this
> microscopic pair of filaments (silver, or carbon or anything else) begin to
> arc over at voltage.
>
> Capacitors that we are dealing with today have had a literal lifetime of
> experiences and any of these may have caused a pinhole in the mica. Also,
> since mica is a mined mineral there are different grades of mica that is
> used in caps. They would classify mica based upon its optical clarity but
> just how many trace contaminants (iron molecules from the geology the mica
> was formed in) or other defects just do not get caught in the mass
> production of capacitors.
>
> *Ms. Tisha Hayes, AA4HA*
>