[TowerTalk] aluminum joint preparation

[Kurt Andress]

Bill Aycock wrote:

> I know this has been covered in the last six months, but, at the time, I
> had no idea I would be in a position to need the data this soon. (Does this
> excuse sound familiar?)
>
> I am about to re-furbish and re-assemble a old CushCraft tri-bander. It
> seems to be in pretty good shape. the questions I need to cover are:
> 1. how should I clean the joints .
> 2. what should I use to protect the joints?
> 3. what is the difference in the "inside" end and the "outside" end of the
> traps? ( the markings are long gone)

Hi Bill,
I made acouple of detaild posts on this subject a while back.  You should be
able to find them in the archives.
Relating to the responses of others about your questions. Both the Penetrox and
OXGARD materials work well. The OXGARD is carried at the local Supply One
store. I have to get the penetrox from the local electrical supply house.
Be careful to use the right Penetrox compund. Penetrox A & A-13 contain zinc
particles and are for aluminum-aluminum or aluminum-copper connections. The A
has a petroleum based grease, not recommended for use with rubber or
polyethelyne insulated conductors. The A-13 has a non-petroleum base vehicle
for use with the insulated conductors. Both are suitable for element joints.
Stay away from the Penetrox E material. It has copper particles for use in
copper-copper connections. Use this stuff for making connections in the ground
system. See previous posts for description of problems.
I think this is why Tom, W7WHY had problems with the KLM joints. They used to
provide a copper paste with their antennas. Don't know what they are doing
today.

Regarding preparation, I think it is absolutely critical (see previous posts).
Make sure you obtain a fresh bare aluminum surface, free from all residues.
Sandpaper, wire brush, Scothbrite work well.

73, Kurt


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