[TowerTalk] Penatrox Substitute

[Kurt Andress]

DavidC wrote:
> 
> Kurt:
> 
>    What about the lithium grease sold at WalMart for marine applications?
> 
> - Thanks! & 73, DavidC  K1YP in Hudson, FL
> 

Hi David,

Hmmm..
Don't know, haven't tried it, or considered it.

Got to answer three questions to know the answer.

1) How conductive is the lithium compound in the grease?

All my cool chemistry books are at work. So, I looked in my daughters
encyclopedia. 
Lithium is an alkali metal that does not readily occur alone in nature.
It readily reacts with moisture to produce an oxide, releasing the
hydrogen.
So, I'd guess your grease has one of the many possible lithium oxides in
it.
Lithium is just about as far as one can get from the conductive metals
we know on the periodic table of elements (not too many free electrons).
So, it might not be a great conductor. 
Someone else with handy reference material should be able to answer this
one.


2) What is the galvanic reactivity of the particulate material?

I don't know where, whatever the particle compound, is on the galvanic
chart, not listed in any of mine. It's likely an inert material, and
therefore okay galvanically, but if it's truly inert, it's probably not
a good conductor.


2) What is the paste vehicle (greasy stuff) in the compound?

It says "for marine applications", so it may be a moisture resistant
petroleum or other synthetic compound.

Being "moisture resistant" is good but that is also a relative term.
There are very few things in this world that are "moisture proof!".

This all has to do with the chemical structure of a material. I'm not a
chemist, but most of this stuff is readily attainable in the public
domain. 
Sometimes the issue is a chemical reaction between the moisture,
atmospheric air, and the base material. 
The other general concern is whether or not a material will allow water
molecules to make their way into the structure and interefere with the
parent materials interconnecting links. They don't have to chemically
react to cause a disruption in the structure. The water can just get in
there and create larger spaces between the parent material connections.
Then we can add thermal cycling, and the water can become a significant
enough volume of the material for the compound to lose its original
properties.

My experience with the moisture resistant petroleum lubricants is that
they won't as readily mix with the moisture and create a foamy
substance. This doesn't mean that they can't be displaced by the
moisture, diluting them,  causing a reduction in lubricating
performance. The important thing to remember here is, that trapping
ionized water in a connection that has dissimilar materials is just
about as bad as having the grease leave and letting the moisture get in
there to react with the dissimilar materials.
That difference is "just a matter of time."


Bet that's more than you asked for, but we've been talking about this
one for a very long time, and the fundamentals don't seem to have found
a home.

Regardless of any anecdotal evidence (I.E. "Mine came apart..."),
putting dissimilar materials together with atmospheric moisture is just
plain bad practice (I.E. "What is all that hard crusty dark stuff I
can't get off the tubes?"). 
Like I said, it's one of those YMMV things.

Sorry, I don't know the answer to your question right now. But, if
forced to guess, I'd give it "two thumbs down."

Once you've used the silicone grease, you'll understand what moisture
resistance and tenacity is. Completely a different time zone from the
other stuff.

$16 for a forever supply of the stuff that will never CAUSE corrosion
and keeps the moisture out seems quite reasonable to me. 
That kind of investment won't prevent anyone on this reflector from
getting a new transciever, new antenna, new tower, or other assorted
station bizo's. 
I think it will put an end to the reccurences of galvanic corrosion in
antenna conections!

It's often just a matter of perspective.

Mine is, that I'll never again use any of those galvanically active,
petroleum based compounds, when there is a better, easily affordable
solution.

I just offered it, as it appeared that the current discussion was
completely devoid of any reference to the other option, except for the
nice material and supplier listing, supplied by one, that actually made
mention of it.

I'll shut up now, this subject has it's own life...maybe antenna joint
compounds are just like the antennas they are used on. The best one is
the one I have.

-- 
73, Kurt, K7NV

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