[Antennas] Penetrox, Noalox, Alumatrox

[Eric Lemmon]

Barry,

You presented an excellent tutorial on the basic uses of Penetrox and
similar anti-oxidant compounds.  I'd like to add a few points:

1.  The trademark "Penetrox" covers a family of compounds, some of which
contain zinc granules in a petroleum base (Penetrox-A) or in a silicone
base (Penetrox-A13), and at least one that contains only copper granules
(Penetrox-E).

2.  I disagree with the statement that such compounds are not really
designed to be anti-galling agents.  In fact, the Aluma-Kote (zinc) and
Kopr-Kote (copper) compounds sold by Thomas & Betts for the same
purposes as Penetrox , et al, is actually Jet-Lube anti-seize compound
with a different label!  I know this to be true, because the MSDS sheet
lists Jet-Lube as the manufacturer, and the formulation thereon is
identical to the MSDS listing for Jet-Lube aviation-grade anti-seize
compound.

3.  On the issue of using a zinc-containing compound on
aluminum-to-copper connections, I have never had a problem with this-
but then, I am very careful to clean the contact surfaces well and seal
the joint against moisture intrusion.  I will acknowledge that most
large aluminum terminal lugs that are UL-listed for copper conductors
(such as those in a typical electrical service panel) have a thin tin
plating to separate the aluminum from the copper.

I always assemble aluminum antenna sections with Penetrox-A13, and have
never had any of the erratic behavior attributed to noisy or
"electrically loose" elements.  I also use this stuff on  galvanized
steel tower joints, and it ensures that they will come apart easily
years later.

73, Eric Lemmon WB6FLY

"Barry L. Ornitz" wrote:

> Penetrox, Noalox, etc. are materials designed to aid in
> aluminum-to-aluminum electrical connections as an
> antioxidant.  They are not really designed to be primarily
> a lubricating grease or anti-galling agent.  However their
> makeup does contain lubricant which does aid in the
> assembly and disassembly of antennas.
>
> These materials are all made of fine zinc particles
> dispersed in a lubricating binder.  The zinc particles are
> hard and have irregular rough surfaces.  When two pieces of
> aluminum are clamped together with this material in
> between, the zinc particles cut through the surface oxide
> layers on the aluminum and provide better electrical
> contact.  The binder, which is generally a light organic
> material similar to thin petroleum jelly, tends to prevent
> oxygen from getting to the contact points.  Sometimes an
> aluminum soap such as aluminum stearate is added to the
> binder.
>
> Zinc is an excellent material for use here.  Not only is it
> harder than aluminum, a property needed to "bite through"
> the oxide layers, zinc is also compatible with aluminum
> from a galvanic corrosion standpoint.
>
> The Penetrox and Noalox I have used are not what I would
> consider super messy to use.  They are usually a gray,
> somewhat gritty, grease.  They are quite different from the
> black graphite or molybdenum disilicide containing
> automotive greases used to prevent seizing and galling of
> high temperature bolts.  These automotive materials are not
> really suitable for the aluminum-to-aluminum application
> either.  [For high temperature stainless joints, a silver
> containing grease is used to prevent galling.]
>
> While you often see Penetrox suggested for aluminum-to-
> copper joints, it no longer provides the proper galvanic
> compatibility here.  It is probably better than nothing but
> copper-to-aluminum joints will always create galvanic
> corrosion problems.
>
> I generally buy Penetrox of Noalox at industrial electrical
> supply stores.  I know Home Depot often carries one or the
> other.
>
>         Dr. Barry L. Ornitz     WA4VZQ     ornitz@tricon.net
>
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>
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