Re: Topband: Verifying integrity of 75 ohm coax.

["Tom W8JI" <w8ji@w8ji.com>]

> Those switch contacts carried 5 VDC at a milliamp (at most!) to and from a
> CMOS interface IC (similar to BCD, but it wasn't) on the logic board of 
> the
> computer that ran the machine.
>
> And I don't think that's enough to make anything arc, do you? :-)
>
> I wish I would have saved that switch that I greased, or took a good photo
> of it. The circle of grease around the contacts turned bright silver,
> almost white, with no visible traces of the underlying phosphor bronze
> contact base metal. And from the amount and appearance of the resulting
> "silver grease" perhaps the contacts had a heavier-than-normal thickness 
> of
> silver plating. Whatever the case, I never expected to see what I did, and
> I'll never forget how the machine acted after so short a time, how the
> switch looked when I took it out, and how amazed we were. If that grease 
> we
> had wasn't abrasive, I just don't know how else to explain what happened
> there.
I don't think it is that important or meaningful to the world, Mike. None of 
that means silicon grease is abrasive and should not be used as a lube, 
which I think was the original statement. There are too many millions of 
applications where it works as a lubricant without issue.
The only documented cases of silicone grease causing an issue in switches is 
from silicone-carbide is when contacts arc through the grease. It actually 
is a very common lube for many applications.
73 Tom 

_________________
Topband Reflector Archives - http://www.contesting.com/_topband