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Re: [TowerTalk] Star guying

Subject: Re: [TowerTalk] Star guying
Date: Sat, 1 Dec 2007 10:47:58 EST
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In a message dated 11/30/2007 9:05:18 A.M. Pacific Standard Time, writes:

>  I have a question about star guying.

>  This  fall I erected 170 feet of Rohn 55.  The tower is mounted on a  pier
pin with a tapered base section.  I have another 20 feet to go,  but due
to weather, that will have to wait until next spring.  The  only antenna
on the tower at this point is my full size 3-el 30 meter beam  at 100 ft.
After completing the tower, I plan to put long boom (50')  yagis for
other bands at 160 and 190 ft.

>  Even with just  the 30 m beam on the tower, the tower exhibits a modest
amount of twisting  at the 100 ft. level. when the wind blows (which is
most of the time here  on the Great Plains).  I'm thinking that star
guying at one or more  levels would help reduce the torque.  However,
since I haven't used  star guying before, I don't know if I should just
do this at the 100'  level, the 190' level, or both. 
    While I agree with Frank, W3LPL, about the stress  issues on the legs due 
to increased guy tension, 55G is good to at least 300  feet so the additional 
stresses introduced by the 6-way guying at 190' should  be well within the 
design limits. (I'm not an engineer but I've worked on  several towers.) 
    Using a star bracket will certainly lock down the  tower and prevent it 
from twisting but I've never heard of a properly  installed Rohn tower failing 
because of too much wind induced torque. They'll  take a fair amount of abuse 
even when overstressed so either way I'd say  you're okay. 
    One thing you can do is to have the guy wires  mounted as close to the 
rotator plate as possible. That way the torque is  transmitted directly to the 
guy wires without as much influence on the tower  itself. 
Cheers & GL, 
Steve    K7LXC


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