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[TowerTalk] Inspecting tower sections

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Subject: [TowerTalk] Inspecting tower sections
From: (Eric Gustafson)
Date: Wed, 8 Dec 1999 16:04:46 -0700

Hi Guys,

See my comments below.

>From: "Dave D'Epagnier" <>
To: <>
>Date: Wed, 8 Dec 1999 13:48:08 -0700 
>Yes, I know what you're thinking ... aluminum and copper will
>cause corrosion. I thought the same but he assures me that
>corrosion does not occur when this product is used on aluminum,
>stainless or galvanized fittings. I believe him. It's got
>"anti-oxidants and corrosion inhibitors", say the

Both the anti-oxidants and the corrosion inhibitors _are_ the
grease.  The function of the grease is to keep the atmospheric
oxygen and any liquid electrolyte from being able to touch any of
the material protected by the grease.

>By the way there is nothing wrong with having a grease carrier.
>A lot of people use Dow Corning Pure Silicone Grease for coax
>cable fittings.  It works fine.

This is true.

The issue isn't whether grease is a good idea, the issue is
specifically what kind of grease is appropriate.  If the grease
is virtually any of the petroleum based varieties, in my
experience, it will eventually leave the joint - either by
solvent action or by evaporation.  Of course, the time required
for damage to occur is _highly_ dependent on the specific
environment that the system is exposed to.  Here in Tucson, none
of this is a terribly important consideration even though it
_does_ rain - sometimes (I'm told).  But there are many places
where this consideration is critical (coastal areas, acid rain
zones, etc.).

If the silicone grease is a variety with the right properties, it
will be insoluble in the solvents it is likely to encounter in
your antenna system and it will not evaporate.

In any case, if the grease disappears, any unprotected outdoor
joint which clamps dissimilar metals together is in trouble.

When clamping aluminum to aluminum, there is absolutely no need
for any kind of filler metal.  The grease by itself is good
enough to protect the joint.  The joint will be plenty conductive
if the surfaces were cleaned immediately prior to applying the
grease.  So why would we want to risk corrosion damage to the
aluminum by including a copper filler metal just in case the
grease _does_ happen to be the "leaving kind"?

73, Eric  N7CL

>From:  Merv Schweigert []
>Sent:  Wednesday, December 08, 1999 11:23 AM
>Interesting, looked up SS-30 and it reads :
>SS-30 Antisieze compound for stainless steel, contains pure
>metallic copper in a non - melting grease base.  Uses: battery
>terminals and bus bar connections..
>Dont think I would be interested in using copper between my
>aluminum antenna joints.  Or grease base for that matter ..
>Must be missing something here..
>Merv K9FD

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