In a message dated 96-08-08 11:07:27 EDT, you write:
>Mast/rotor arrangement at the top is very solid
>(2.5 inch high strength alloy and a prop pitch), but
>the whole tower turns at the top about 5 degrees or
>so when the wind blows or when the rotor starts
>and stops. I have a massive rubber shaft-coupler
>between the rotor and the mast that helps absorb
>shock-torque, but the top couple of sections
>turn nonetheless.
>Should I be worried? I am considering going
>to a dual-guy arrangement for the top set of
>guys, with the big torque-controlling ears at
>the top (not sure of the correct terminology.)
>
Hi, Geoff --
Your 5 degree movement seems like a lot. Are your guy wires tensioned
to their 10% specification? Perhaps they are under-tensioned. Are you using
the Rohn GA45G Guy Assembly? Or the old torque arms?
>Anyone know if these attachment brackets are Rohn
>stock, and the best way to calculate how much torque
>they will assest?
>
The Rohn TA45 Torque Arm Stabilizer Assembly, sometimes called a 'star
bracket', is the part you're looking for. It is used for dish installations
and virtually eliminates tower twisting; it really locks down the tower.
Many station owners with full-sized 40M beams or 75 M yagis use this
approach for tower stabilization.
As far as how much torque, you could call the factory (309-697-4400) and
ask but they might not have the answer or be willing to share it with you.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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