Topband: Verifying integrity of 75 ohm coax.

[Mike Waters]

Silicone dielectric compound ("grease") should not be used as a lubricant.
It's actually somewhat abrasive.

Hoping to extend its life, I once tried that stuff on a high-quality
silver-plated rotary wafer switch on a piece of industrial machinery at the
last place I worked. The switch actually failed FASTER with the silicone
dielectric compound than they did before I tried it. Silicone dielectric
grease does NOT have lubricating qualities. Basically, it contains fine
sand (silica) which is abrasive. The silica wore the plating off after only
a few weeks, and was starting to work on the base metal. It became very
intermittent and had to be replaced with a new switch.

I wish I had taken a photo of that switch! The silicone dielectric grease
was no longer clear (well, translucent), but bright silver! It looked like
silver paste. The silver plating had become thoroughly mixed with the
grease, actually making the grease conductive!

Silicone dielectric compound is fine for outside RF connectors to keep
water and condensation from making them corrode and fail. But it's not for
lubrication between moving surfaces.

I suppose it might be OK to use it on a switch that only rarely gets used,
but not one that gets regular use.

73, Mike
www.w0btu.com

On Fri, Nov 22, 2013 at 9:34 AM, Roger Parsons <ve3zi at yahoo.com> wrote:

>  The TVs of that era (in the UK at least) had large rotating turrets to
> select the channel. We used to burnish the contacts with 'Silvo' and then
> smear silicone grease over them. That part of the set was then much more
> reliable than as supplied new.
>