[TowerTalk] TH-3 Problems

[Kurt Andress]

Paul McInnish - K4BET wrote:

> Would like to suggest that one NOT use steel wool to clean aluminum joints
> on antennas.  The steel wool will 'shred', 'disintegrate' and imbed minute
> particles in the aluminum... and eventually will rust and set up a high
> resistance joint. EVEN when using the conductive greases and
> anti-oxidants... Pentrox, etc.
>
> Suggest using a product made by 3-M and it is called Scotch Brite pads.
> Paint & body shops use it in place of sand paper in a lot of instances.
> 73,
> Paul
> K4BET

I'll be the first to second this notion about what to use to prepare aluminum for bonding (either electrical or mechanical).
In my last 20 years of preparing aluminum for structural bonding, there are very few materials that compare to simple
Scothbrite for the bond prep.Yes, there are several chemical treatments that are superior, and spec'd for the bonding of the
airplanes you all fly on. But, I think most of us garage antenna builders do not have access to the very best chemical
treatments. So, we get to do the next best thing, that is polishing the substrates with Scothbrite.
The connection needs to be made within 2-3 hours after cleaning. Otherwise, the atmosphere will oxidize the surfaces and
render the connection useless. YMMV, dry climates give you more time, humid ones do not.

Steel wool is anathema to good aluminum bond prep. The steel residues imbedded in the aluminum surface will make really neat
batteries to corrode your connections.




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