Hi,
I would give some thought to that antennas boom torque imbalance problem when
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 the
thing.
Just a thought...it is a known problem that is not kind to the plate.
--
73, Kurt, K7NV
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