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[TowerTalk] More tower concerns

To: <towertalk@contesting.com>
Subject: [TowerTalk] More tower concerns
From: K7LXC@aol.com (K7LXC@aol.com)
Date: Tue, 16 Jan 2001 23:39:57 EST
In a message dated 1/16/01 2:38:00 PM Pacific Standard Time, 
w5ba@compuserve.com writes:

> 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. (60 ft. will support 9.6 sf of antenna...guyed at 25 ft.
>  with
>          3/16 EHS tensioned to 400# and 55 ft. with 1/4 EHS tensioned to 
660#
>          The same tower height, with a single 3/16 EHS 400# set of guys will
>          support 16.7 sf at 70 MPH).

    ACTUALLY there is another 8 sq.ft. of tower capacity available that was 
netted out for a symmetrical commercial antenna mount in the general notes. 
Take a look. So the above example will take 24.7 sq.ft. 

>      2.) 70, 80 and 90 MPH ratings for everything from 40 to 100 ft. of
>  bracketed 45G
>             (60 ft. will support 33.3 sf at 70 MPH, 24.7 sf at 80 MPH and
>  17.0 sf
>              at 90 MPH...bracketed at 23 and 46 ft. levels).
>  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. 

    GOOD THINKING!

>   That's not to say that it "can't" be done...

    YES - that's exactly what that means - it can't be done. 

>  just that if you want to be sure that it is done
>  safely, you'll get
>  someone who is qualified to 'run the numbers' to check the installation.
>  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.

    Yes, you can get the calcs run for a case of beer in some cases. But that 
engineer will arrive at the same conclusion that the manufacturer has.

Cheers,    Steve    K7LXC
Tower Tech 

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