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[TowerTalk] Tri-Ex LM470 Rotor Mounting Plate

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Subject: [TowerTalk] Tri-Ex LM470 Rotor Mounting Plate
From: (Mike Wapner)
Date: Wed, 18 Jul 2001 13:34:07 -0700
I am in-process of installing an LM470 that didn't come with a rotor
mounting plate.  The tower has a heavy duty 2" thrust bearing mounted on the
very top plate.  Also, welded to the underside of this top plate is a 2"
I.D. sleeve with two set screws.  The underside sleeve appears to be stock
Tri-Ex.  There is also a movable triangular galvanized steel plate (1/8"
stock) that fits inside the top section.  This plate also has a 2" I.D.
sleeve with set screws that can be placed almost anywhere within the top
section.  It has small "ears" that catch the diagonal cross members to
prevent it from slipping down the inside of the tower section, but it is not
"attached" to the tower.
I suspect that this movable plate could be used for a rotor mounting plate,
assuming it was appropriately machined to mate to the rotor, but I am
uncomfortable with 1) the thickness of this plate being inadequate and 2)
the fact that it would be held in place vertically only by the weight of the
rotor and the mast pushing down on it.
My total vertical load (antennas & mast) will be approximately 275#, but
this will be taken by the thrust bearing.  The torsional load is
approximately 22 sq. ft. The rotor weight is yet unknown, but will be 45#
Does anyone have a sketch of an "adequate" (at least 1/4" or 3/16" steel)
rotor mounting plate and that also shows how to rigidly affix it inside the
top tower section of a LM470?  I know that Tri-Ex originally offered one, so
I suspect it is documented somewhere.  I can easily fabricate one if I have
the drawing(s).  Thanks
Mike, K6QD

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