Very soon afterwards (a few weeks instead of perhaps a year), the
operator called me over to show me the problem with that switch. I know
what I saw, and I am convinced that it is abrasive. That grease
accelerated
the failure of that switch by a tremendous amount.
This is very interesting and something I also discovered and never
reasoned why, I have used Potable silicone grease inside PL-259 coax
connectors and never had a problem, however, when I have used the same
grease inside the rotary preset switch for my Prosistel rotator controller
box it destroyed the switch in a couple of months, now I know why.
Actually, that flies in the face of everything published about typical
silicone dielectric greases.
What is often stated and documented and applies to this is that silicone
grease will form silicone-carbide when subjected to arcs. Silicone-carbide
is a great abrasive. This is why you cannot use silicone grease in contacts
that arc when switched.
Silicone carbide:
http://www.3m.com/product/information/Waterproof-Silicone-Carbide-Sheet.html
Let's not create a new theory that silicone grease is abrasive, when nothing
supports that theory. Silicone grease is commonly used to lubricate things
that rubs and slide, including switch contacts and potentiometers. It is
used to reduce fretting in sliding connectors that vibrate. It is clearly
not abrasive unless carburized.
If a contact **sparks**, it normally should be left dry or lubricated with
something that does not carburize. The only exception would be if a
manufacturer says otherwise.
73 Tom
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