I have the Rohn Chart that shows RH-25 can self support 1.5 sq.ft of
windload at 70 MPH with no ice.
For 90 MPH is self supports 1.7 sq. ft 30 feet of height (no ICE). The
specs are for 3 - 5/8 feedlines and round antenna members.
If I were doing this and had to climb it, I would install temporary
rope guys and climb in no wind conditions.
20 ft of RH-25 will self support 6.9 sq feet of antenna at 90 mph. I
am really comfortable putting up RH-25 sections with a Gin pole 2 or 3
sections above the temporary guys but not more... so this fits what I
feel is safe when I am on the tower.
-Dave NN5K
Robin Midgett wrote:
>Yes, I can tell you...No, absolutely not! 25G isn't self-supporting
>at any height. Additionally, if you were to erect this 40' tower
>without guying it, someone would have to climb it and install the
>antenna...making for a very dangerous situation. The ice loading
>situation that someone else mentioned is another reason not to do this.
>Granted, hams have used this technique and gotten away with it for
>years...but that doesn't justify doing it. You should either guy the
>25G installation or use self-supporting tower.
>
>
>At 05:32 AM 5/10/2006, you wrote:
>
>
>>>-----Original Message-----
>>>From: towertalk-bounces@contesting.com
>>>[mailto:towertalk-bounces@contesting.com] On Behalf Of Martin
>>>& Ann Mein
>>>Sent: Monday, May 08, 2006 8:37 PM
>>>To: Towertalk@contesting.com
>>>Subject: [TowerTalk] self-supporting rohn 25g??
>>>
>>>
>>>Hi all,
>>>Can anyone tell me if it's OK to install a 40' tower, made from
>>>
>>>
>>four 10-foot sections of Rohn 25G, as a self-suppoting
>>
>>
>>>tower? The antenna that wpould be on the tower is a small
>>>
>>>
>>omni-directional circularly-polarized FM antenna for 95.9
>>
>>
>>>MHZ, so it is small with not much windload. How big does the
>>>
>>>
>>cement base have to be? Locally, the minimum concrete order
>>
>>
>>>is 4 yards. We are located in upstate NY. 4 yards would be
>>>
>>>
>>somewhere around a 4.5' X 4.5' X 5.5' foot base.
>>
>>
>>>Thanks and 73...
>>>Jeff KP3FT
>>>Spirit And Truth Christian Radio WJIH-LP 95.9
>>>
>>>
>
>Thanks,
>Robin Midgett K4IDC
>615-322-5836 office - rolls to pager
>615-835-7699 pager
>615-301-1642 home
>K4IDC@comcast.net
>http://www.people.vanderbilt.edu/~robin.midgett/index.htm
>
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>
>
>
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>
>
>
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