Topband: Verifying integrity of 75 ohm coax.

[Greg-N4CC]

Silicone is totally different from silica.  Silica in its most common form is "sand".  Silicone is a name for a class of compounds based on the element silicon.  The properties can vary significantly.  Silicones are commonly used for lubrication and defoaming applications.  73, Greg-N4CC

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-------- Original message --------
From: Tom W8JI <w8ji at w8ji.com> 
Date: 11/24/2013  6:11 AM  (GMT-07:00) 
To: Mike Waters <mikewate at gmail.com>,topband <topband at contesting.com> 
Subject: Re: Topband: Verifying integrity of 75 ohm coax. 
 
> Anything is possible, but I know what I used and saw, Tom. It was a small
> squeeze tube labeled "silicone dielectric grease".
>

I don't doubt your failure observations. I just doubt the cause, because the 
abrasive problem from silica is not supported. If abrasiveness were an 
actual problem, warnings or complaints should frequently appear. If silica 
or abrasives in the grease make dielectric grease bad for friction life of 
rotary contacts, it would also logically follow TV set manufacturers and 
other switch and control users or manufacturers would not use silicon grease 
in gold plated wiping contacts such as old TV tuners, in controls and 
switches, or to reduce fretting corrosion in spring contacts such as on 
automotive connectors or board connectors.

As a matter of fact, when the manufacturer of silver plated rotary meter 
switches in Ameritron meter switches stopped using silicone grease the 
switches went bad very fast. Silicone liquid is also a standard meter 
movement dampener in panel meter jewels.

Searches reveal use as a lubricant is everywhere, but nothing speaks of 
abrasiveness or contact damage unless an arc converts it to 
silicone-carbide. 

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