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Subject: ROHN 25G QUIERY
From: (Rod Fitz-Randolph)
Date: Sun, 15 Dec 1996 22:07:24 -0600
On Fri, 13 Dec 1996 16:41:17 -0500, Steve  K7LXC wrote:

>    In regard to the homebrewed angle iron arms, yes, they probably add a
>little bit of additional torque resistance but in light of the above
>comments, probably little if any.  But, no, I wouldn't recommend that anyone
>take this approach.  Unless you have calculated the forces on the new
>appurtenances and had them fabricated by a qualified person, DO NOT do this.
> A much better approach is to use the hardware designed by the manufacturer.
> In the case of Rohn, they make a 'star bracket' where each guy point has two
>guy wires attached to it.  This approach is guaranteed to eliminate any
>twisting of a tower in the wind.
>     BTW, in the case of 25G and the aforementioned home brew arms, a six
>foot piece of angle means that 2.5 feet sticks out on either side of the
>tower where the guy wire attaches to it.  Any wind pressure on the tower will
>result in 2.5 times the force on the sidearm (force times distance,
>remember).  And since it sticks out horizontally instead of inline with the
>guys like the Rohn guy assemblies, it's even MORE likely to bend.  Get my
This isn't a flame, Steve, but I don't understand how something "inline" with
the guys can do much to prevent twisting as opposed to a 6 foot 2" steel angle
that is guyed at right angles to the angle.  That provides quite a bit of
resistance to twisting and has been used on the 130 Rohn 25G tower with a 402CD
at 140 feet and a TH7DXX at 132 feet very successfully here in winds in excess
of 60 miles per hour.  There was no perceptible twisting of the tower during
that gale force wind.  How in the name of all that's holy is that supposed to
make it MORE likely to bend???????????  I don't get your drift.  I don't think
you have a very clear picture of the steel angle u-bolted to the two tower legs,
protruding out past that by 2 1/2 feet and guyed then at right angles to the
steel angle.

73, Rod

Roderick M. Fitz-Randolph
79 Highland Hills Cove,
Jackson, TN  38305
(901) 661-9278 (Phone - after 10 AM and prior to 9 PM)
(901) 664-7539 (FAX - any time of day or night)

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