There is probably no harm in some twist unless it oscillates like the
Tacoma Narrows bridge. K4JA's rotating 200' AB105 tower with large 40m
beams broke apart during very strong winds but no one knows if it would
have survived with star guys. His other rotating towers with smaller
antennas survived.
Personally I like star guys and having my rotators not slip in heavy winds.
John KK9A
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Star guys vs rotating tower ?
From: Richard Thorne <rthorne@rthorne.net>
Date: Mon, 16 Oct 2017 09:17:15 -0500
Jim,
I have a 140' rotating tower.
We get regular high winds here in Amarillo. The last big wind storm was
back in June when we had 80mph straight line winds. Both my
towers/antennas survived nicely, but my fence on the north side was blown
over and it had steel posts.
My rotating tower will twist in the wind. If the winds are high enough it
will end up moving the prop pitch rotor in one direction or the other. If
I have a wind event that moves the tower I'll walk out with my iphone,
bring up the compass app and take the new reading. Then I go back to the
shack and enter the new heading in my Green Heron rotor controller.
I think it's a good thing that the tower rotates within the rings when it
gets windy as it takes the stress off of the system. Since the prop pitch
doesn't have mechanical stops it's very easy to re-calibrate.
My 2nd tower is 80' of 45g. It's on a pier pin for the same reasons,
wind. The tower can at least twist a bit to relieve the stress on the
tower. It has a normal set of guys vs star guys. I want the tower to
twist freely if needed.
The only problem I have on the 45g tower is the Orion rotor. The stock
mast clamp is terrible. I have to climb the tower several times a year to
re-position the antenna stack. One of these day's I'll order a K7NV or
Champion after market mast clamp. Then again, it may not be a bad thing
for the antenna system to slip a bit vs tearing something up like the
rotor itself.
Rich - N5ZC
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