On 1/16/01 5:36 PM, Gerald D'Entremont at w5ba@compuserve.com wrote:
>Actually, all the back and forth on this caused me to go back and look at MY
>copy of the Rohn Ham Tower Catalog which shows a number of different
>scenarios:
> 1.) 110 MPH Basic wind speed ratings for everything from 40 to 170 ft.
> of 45G.
I looked at this too, in my catalog.
I'd note that none of the 110 mph guyed designs in the Rohn catalog have
more than 5 feet of tower above the top guy. Where as the 90 mph designs
have 9 feet, and some of the 70 mph designs allow 15 feet.
> 2.) 70, 80 and 90 MPH ratings for everything from 40 to 100 ft. of
>bracketed 45G
Yup.
>What it does NOT show is any ratings for bracketed towers in excess of 90
>MPH
>wind speed ratings. My guess is they don't recommend it.
Either that, or the ratings are so low, they can't imagine that it would
be a popular configuration.
At one level a bracketed installation is similar to a guyed one. (The key
difference being that a bracket is supposed to connect to a theoretically
rigid structure, and transfer forces that way, whereas a guy translates
horizontal forces into vertical downforce) A bracketed installation is
something like a guyed installation with a set of guys at the bracket
level.
>ARRL
>has a Volunteer Engineer program, similar to the Volunteer Counsel program
>for
>legal issues, and I'd wager you could find someone to take a look at your
>proposed
>installation for a LOT less than $1800/hr.
This is a good tip, even for us cheap hams. <grin>
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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