John,
Have you really looked at the wind load
you are considering for this on Rohn 25G?
The twisting motions at the top are going to
be LARGE and well past what 25G is spec'd.
That much wind load is better suited on
Rohn 45G as a mimimum.
As the concrete is poured, maybe the best
option is to go to a flate plate base and
sell the 25G and secure the needed 45G.
Or plan on going with a "star" guying at all
levels ... to try and address the torquing.
Just my 2 cents, as you seem well past the
stated design specs for 25G with this.
73 de Billy, AA4NU
-----Original Message-----
>From: Jwpjj@aol.com
>Sent: Jun 11, 2008 6:42 PM
>To: towertalk@contesting.com
>Subject: Re: [TowerTalk] Guying Material and resonance
>
>I am getting ready to install 90' of Rohn 25, base section is all
>done,concrete etc and so are the guying stancheons that are set in concrete as
> well. I
>have the first 10' up and hopefully in a few weeks or so will be ready for
>the rest of the installation. My question is what is preferred, steel guying
>cable or Phillystran cable. One of my concerns ( maybe it should not be) if I
>use steel guying installation, should I be concerned about resonance based on
>the lengths of guying cable. The tower will have a 4 el steppir at approx 98',
> below that there will be a 3 element 40 meter monobander, prosistel rotator
>and fed with LMR400. Will I need to break up the guys? It seems like it would
>be a lot of work if I had too or should I just go for the Phillystran and
>don't be concerned. This is my first guyed tower as I have always have had
>crank ups. I have seen a lot of pictures that have been on this forum and was
>
>wondering what most everyone else uses for guying their towers. The guying
>lengths will be as per Rohn specs, 80% of total height to calculate guys
>lengths.
>
>John, ND1X
>
>
>
>
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