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Re: [TowerTalk] 30 foot Rohn 25G calculations

To: "'Brian Carling'" <bcarling@cfl.rr.com>, "'W2RU - Bud Hippisley'" <W2RU@frontiernet.net>
Subject: Re: [TowerTalk] 30 foot Rohn 25G calculations
From: "chetmoore" <chetmoore@cox.net>
Date: Thu, 12 Feb 2015 13:08:47 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
You do know that rohn makes a house bracket for 25G tower, right?????

Chet  n4fx

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Brian 
Carling
Sent: Thursday, February 12, 2015 1:03 PM
To: W2RU - Bud Hippisley
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] 30 foot Rohn 25G calculations

Many thanks Bud.

I will need to review which version they are using. Yes I had someone pointing 
me in the direction of a freestanding tower but I think I may go to using guys.

It's either that or trade my tower sections in on a stronger better built 
freestanding tower designed for that purpose. I only need about 24 to 28 feet 
in height. Maximum.

Best regards - Brian Carling
AF4K Crystals Co.
117 Sterling Pine St.
Sanford, FL 32773

Tel: +USA 321-262-5471




> On Feb 12, 2015, at 12:27 PM, W2RU - Bud Hippisley <W2RU@frontiernet.net> 
> wrote:
> 
> 
>> On Feb 12, 2015, at 9:58 10AM, bcarling@cfl.rr.com wrote:
>> I am putting together a permit application with my city which 
>> requires certfication for 139 mph for three second gusts as in TI-222 spec. 
>> Also steady 100 or 110 mph I think.
>> We are making a 30 foot Rohn 25G tower according to the Rohn 
>> specification with  4 foot cube base of concrete with no guys.
> 
> I’m not sure I understand what you’re hoping to find.
> 
> My 4-year old Rohn catalog makes it VERY clear that 30 feet of Rohn 25 can 
> hold only 1.7 sq. ft. of added antenna when the environment is 90 mph 
> (ANSI/EIA-222 Rev. E) and NO ICE.  (For areas that experience icing, Rohn 25 
> is specified by the manufacturer at ZERO sq. ft. of additional antenna load!) 
>  From your e-mail address and the wind speeds you mention, I’m going to guess 
> you’re in Central Florida, and I daresay a 90-mph Rohn EIA-222 Rev. E 
> specification is not going to be adequate for your city.
> 
> Nowhere in your posting do you mention what total antenna, rotator, feedline, 
> etc. wind surface area or wind load you anticipate putting on this tower.  
> But my guess is that NO freestanding 30’ Rohn 25 tower is going to make the 
> grade.
> 
> Also, you fail to mention which version of TIA/EIA-222 your city is using.  
> The latest I’m aware of is Rev. G — a substantial revision from previous 
> methods of specifying wind loading.
> 
> Bud, W2RU
> 
> 
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