[Towertalk] Failed KT34XA Boom/Mast Plate

Jim White k4oj@tampabay.rr.com
Wed, 27 Mar 2002 00:40:10 -0500

...some short english chick in a long black coat wanted to post the

"You are the weakest link...........


31 days til the Florida QSO Party!

Jim, K4OJ

----- Original Message -----
From: "Kurt Andress" <K7NV@contesting.com>
To: "towertalk" <towertalk@contesting.com>
Sent: Wednesday, March 27, 2002 12:04 AM
Subject: [Towertalk] Failed KT34XA Boom/Mast Plate

> Hi,
> I would give some thought to that antennas boom torque imbalance problem
> pondering the plate failure.
> The imbalance is a fairly consistent feature in those old KLM antennas.
> Asymmetric element spacing, with the mast mounted at the antenna CG
instead of
> the boom center.
> My XA used to do the "hula" every time the wind came. Always had to wait
for it
> to pass neutral, between gusts, for the rotator brake to unlock.
> I'm not sure what the torque values are for the XA. My boom is
> now holding up wire antennas, and I can't find the manual.
> The 5 el KLM 20, on the 42' boom will stall a T2X with around 30 mph of
> sustained wind, boom broadside. The "effective moment" rating says it
should be
> ok, but I don't think it anticipated this kind of problem.
> The XA might not be as bad, just similar. If somebody has dimensions, it's
> pretty easy to figure out.
> Could have been a fatigue problem.
> When the ice and wind came, the imbalance worsened, and may have finished
> thing.
> Just a thought...it is a known problem that is not kind to the plate.
> --
> 73, Kurt, K7NV
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