[TowerTalk] Rohn 25

[Hank Lonberg]

Well you are correct in that it is shown in the consumer catalog and the
chart is dated 1987 and references 222-E. 222-F the latest standard differs
from 222-E. I would not bet on a 40' 25g and ever recommend that a client
use it unguyed. Your mileage may vary.

73
Hank / KR7X


-----Original Message-----
From: Blake Bowers [mailto:bbowers at townsqr.com] 
Sent: Saturday, January 29, 2005 2:21 PM
To: Hank Lonberg; TowerTalk at contesting.com
Subject: Re: [TowerTalk] Rohn 25

Page 25G-1, and page 25G-2 of the Rohn consumer catalog.

Their design charts, their design drawings.




> Blake:
> I beg to differ with you.
>
> Using TIA/EIA 222-F wind loading criteria and 70 mph wind velocity (min.
> recommended) a 40 foot section of Rohn, 25g un-guyed and cantilevered will
> develop a moment at the base of 7200 ft-lbs at the base. This is without 
> an
> antenna load, just the tower itself. The published allowable moment for 
> 25g
> ,by Rohn, with a 1/3 increase for wind loading duration is 6,720 ft-lbs. 
> At
> 40 feet it is clearly overstressed. How do you say that this is ok and 
> that
> Rohn fully supports this?
>