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[TowerTalk] Flex coupling for rotators

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Subject: [TowerTalk] Flex coupling for rotators
From: (J. Kincade)
Date: Tue, 03 Jul 2001 06:42:43 -0500
Wanted to bounce an idea off the collective list brainpower:

I read about exotic and complicated ways to hoist the mast up to work on
rotators. It would be extremely nice to be able to remove my rotator without
having to hoist/move the mast vertically at all. My new 45G setup will have
2 rotor shelves/TB-3's and a 21' mast (10' out the top, 11' inside).

I'm thinking of a short steel tubing sleeve with an ID that will just slip
over the 2" OD of the bottom of the mast. Bottom of the mast and top of the
sleeve would be carefully drilled for a hefty galvanized through-bolt. When
removing the rotator in the future, I should be able to just pull the
through bolt and slide the sleeve up, temporarily slipping the through bolt
back in through a second hole in the bottom of the sleeve to hold it up out
of the way, pull the rotator, etc. The second thrust bearing and a muffler
clamp with a piece of angle welded to it U-bolted to a tower leg would keep
everything from flopping around while the rotator is out, and add some
safety against vertical mast slipping. The Yaesu 1000 is self-centering and
adjustable to fit about any size sleeve in this application. Or, as an
alternative, maybe some sort of easily removable heavy duty rubber coupling
is available that would simply fit between a short rotor stub of 2" mast and
the remainder of the mast. Don't like that as well, though, I'd fear
excessive flex might cause constant twisting around of the antennas in the
wind, unless the rubber coupling was really stiff.

Is anybody using a setup like this, and how is it working? The only negative
possibility I see is the top of the steel sleeve might permanently deform
from longterm bolt pressure, and be difficult to slide up. Maybe a single
slot in the sleeve at 90 degrees from the bolt holes for springiness would
help prevent that.

Comments welcome!

73, Jerry W5KP     Mustang, Oklahoma

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