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[TowerTalk] rebuilding a TH-7 today

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Subject: [TowerTalk] rebuilding a TH-7 today
From: (Gary McDuffie, Sr.)
Date: Sat, 10 Jul 1999 09:57:35 -0600
On Sat, 10 Jul 1999 06:36:37 -0700, Jonathan Kaplan wrote:

>       In a few hours, I'm hosting an antenna party to mount
> antennas on my new tower (it took me 7 months to get
> the permit through People's Republic of Malibu). I have
> a used TH-7 I recently bought laid out on the ground,
> ready for re-assembly. I know there's been some discussion
> in the past about prepping the metal-to-metal joints.
> What is the group's reccommendation for removing old
> oxidation and insuring good permanent contacts? 

I just redid a TH7 and it went very well.  I pulled apart all of the
sliding joints and cleaned them with whatever would work.  Most of the
time it was simply a dry paper towel.  The old stuff was about 13 years
old, so it was pretty dry and cakey.  I wouldn't hesitate to use almost
anything on it, as long as you leave it dry and greaseless when you are

Go to your local electrical supply house and get a bottle of aluminum
anti-oxidant to do the joints when you put it back together.  There are
some AOs that say copper only, but some are for both copper and
aluminum.  The one I found here was Ilsco brand "De-Ox" "For all
aluminum and/or copper terminations".  Spread it liberally over the full
surface of the overlap, slide it together, and wipe off the excess.  I
see no reason to use it sparingly.  YMMV.  Electrical contact is only
made at the compression clamp anyway.  I even put a little on the
threads of the screws and bolts.  I know, maybe it was a waste of time,
but I wanted to see how it would hold up.  I plan on taking the antenna
down within a year and putting up my old KT34XA for comparison, and I
can inspect the results then.

DO use the modified element length measurements when you put it back
together.  It moves it down the band and covers the CW part better.
This will work fine over the whole band, unless you work the very top
end of 20.

73 and GL
Gary - AGØN
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