[TowerTalk] non conductive sealant

[K7LXC at aol.com]

From: "FireBrick" <w9ol at billnjudy.com>
To: "TowerTalk List" <towertalk at contesting.com>
Sent: Saturday, October 02, 2004 4:35 AM
Subject: [TowerTalk] non conductive sealant


> Can anyone suggest of brand of sealant that can be used on antennas that's
non conductive?
> I'm thinking about silicone type sealants.
>
> I had tested a glob of silicone I had using the unscientific VOM and found
that it was
> conductive.

I guess my question is where are you going to use it and for what purpose? What does the manufacturer say? Do they say to seal whatever it is you're worried about? 

For aluminum joints you just need an antioxidant in there. For coax joints you need good electrical tape and a vapor barrier to prevent water incursion. 

The problem with RTV (room temperature vulcanizing) is that it outgasses an acid while curing and the acid can get into your joint (acetic acid? I'm going from memory here). It is NOT recommended for electrical-type applications.

If you insist on using RTV, get the kind for aquariam use - it doesn't have the outgas problem. 

For coax connections, use a couple of wraps of Scotch 33 or 88, a butyl rubber vapor-wrap layer, and then 2-3 more wraps of electrical tape. That's a bomb-proof professional joint. 

Cheers, 
Steve    K7LXC
TOWER TECH -
Professional tower services for commercial and amateur 
Cell: 206-890-4188