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[TowerTalk] Rotor Shims

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Subject: [TowerTalk] Rotor Shims
From: (Dale L. Martin)
Date: Tue, 30 Dec 1997 18:59:11 -0600
During CQ WW CW, late Sunday afternoon, my rotor froze...with the antenna
pointing at Europe.  Nothing I could do on the ground could shake it loose.
I checked all voltages and resistances and everything read nominal.

Today, I had a chance to go up and see what was happening.  I had spoken
with Telex Hy-Gain and my plan was to remove the rotor and send it off for
maintenance/repair--It had been up there even before I bought the house 11
years ago (was it really that long ago, Tom?).

What I found was that, when I loosened the mast clamp on the rotor, the beam
was hard to turn.  But after rotating it around by hand a couple of times,
it seemed smoother and easier to move.  Rather than go down the tower, run
some rotator tests from the control box to see if the rotor would even turn
without a load, I simply removed it and lowered it to the ground.  It has
now been shipped off to Telex Hy-Gain.

While it was clamped in the rotor mast clamp, the mast looked very much like
it was hard against one side of the Rohn 25G pointy top sleeve.  When I had
spun the mast I did not notice any wobble in the lower end of the mast.
Aside from various stuff that might have built up in the sleeve (when I
removed the rotor from under the mast, a pecan fell out of the mast!  This
is a 70' tower, folks!  There ain't no pecan tree in sight!--Tom, did you
put it there for luck?) I can only think that the misalignment was enough to
cause the rotor to not be able to rotate through that spot.  It seems
incredible though.....

I'm going to take another look at the mast --- maybe take it off the tower
and check it's true--maybe it's bent.

If it's straight, I can only think to use the shims referenced in the CDE
rotor manual.  What type of material is suitable as shim material?  My
understanding of what I read in the manual is that the shimstock should be
wrapped around the mast to keep the mast centered in the rotor clamp.  Will
Aluminum sheet metal work?

Thanks in advance for any information/help.

And, Happy New Year to all on the reflector.

Dale Martin, KG5U

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