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[TowerTalk] KLM KT34 antenna ID help needed

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Subject: [TowerTalk] KLM KT34 antenna ID help needed
From: (Larry Schimelpfenig)
Date: Sat Jul 12 14:43:56 2003

The KT34XA manual shows two boom configurations consisting of four pieces as

8'6" 8'6" 8'6" 8' (3 pieces swaged)
8' 8'6" 8' 8' (1 piece swaged and two 16" inserts

The KT36XA (M2) manual shows five pieces. Four are 95" and swaged. The fifth
is 28" and straight.

The caps that come with the M2 KT36XA upgrade kit are black. When I rebuilt
my KT34XA using KLM parts about 4-5 years ago the caps were blue.

I think it was about two years ago that KLM out of Washington State shut
down. I assume you know the rest of the history of KLM and M2.

I think that M2 realized that the straps were one of the weak points of the
KT34 series, so I seriously doubt that they ever marketed the KT36 or their
version of the KT34 with anything other than the machined pieces.

I'm not aware of the M2 dimensions being posted anywhere. I'd be a little
concerned about using the new dimensions with the old straps which are
obviously much wider than the new ones.

I've had a lot of experience with the KT34XAs. Built a new one from scratch
in the 79-80 time period. Ten years later it played as well as the day it
went up and the vswr curves looked almost identical. Someone gave me a used
KT34XA in 92. It had been up about five years. I took it completely apart
and gave it a good cleaning. Had it up from 93-96. I think it was 96 that we
had a severe ice storm and the vswr curves went awry. Had it up and down a
half dozen times trying to get it back in shape. The shorting straps had
expanded and it was difficult to get a good connection between the tube caps
and the elements. I finally resorted to using stainless steel sheet metal
screws to pin the straps to the elements. Obviously couldn't do that with
the cap tubes.

I got it back up in 97 and the swr curves were all over the place until I
pulled it down and did the M2 KT36 upgrade in 01.

While I think the M2 upgrade with the machined shorting bars took care of
the problem I had with the straps, I ended up with another problem that was
never resolved.

When I put the antenna up after the M2 KT36 upgrade the vswr curves looked
great and the antenna seemed to play well. After the first rainstorm, the
swr curves went to hell again. When I pulled it down I found that one of the
15 meter tube caps was full of water. As I assembled the new tube cap
assemblies from the M2 kit, I noticed that the caps slipped over the 3/8
inch tubing much easier than they did when I built my first XA. In slipping
the cap on the 3/8 inch tube of the 15 meter capacitor tube to drain the
water, it was very obvious that water had intruded under the insulator cap
where it surrounded the 3/8 inch tube.

I discussed the problem with M2 and described the problem as a loose fit
between the insulator caps and the 3/8 inch tube. They sent a new bag of
insulators. While I was working with the new insulators I noticed they were
just as loose as the originals. Then I tried slipping the new caps over some
of the old 3/8 inch tubing. Snug fit. I got in touch with M2 once more and
reported this. Never heard back. I decided the hell with it and reopened or
drilled new drain holes at one end of each of the tube caps. That helped for
a while, but I think I need to open the second hole and make sure the first
is clear.

My warning to anyone who purchases one of the M2 tribanders is that if you
don't find it real difficult to pull the cap insulators over the 3/8 inch
tubing, you're going to have a problem with water intrusion.

My feeling on the KLM KT34XA is that if assembled correctly when new, they
held up real well. With 20/20 hindsight I would never try to rebuild one of
the KLM antennas reusing the original straps. Either replace the straps or
go with the M2 upgrade kit.

Finally, after hauling my XA up and down the tower as much as I did, I
out a way to remove the two driven elements without pulling the antenna off
the tower. It's a process that allows one to pull the boom through the
boom to element clamp far enough to reach both of the driven elements to
remove them. The first director is obviously not a problem to remove being
positioned right next to the mast. If anyone's interested in the process let
me know and I'll post it here.

As a final observation, I found the XA to be a canon on 10, worked great on
20, and seemed to be lacking a bit on 15 meters. Many others have made the
same observation. The f/b wasn't all that great, but for my purposes that
may have been a benefit.

73 de Larry K7SV

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