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Re: [TowerTalk] Horizontal tower movement at the top

Subject: Re: [TowerTalk] Horizontal tower movement at the top
From: "Pat Barthelow" <>
Date: Mon, 07 May 2007 13:43:28 -0700
List-post: <>
Clay, and group:

Garry, NI6T, is an avid, successful contester/DXer, with just about all the 
awards you can get, with an antenna(s) high in a redwood tree, and could 
give a lot of seasoned advice to your problem.
Contact him:
73,   Pat, AA6EG

>From: "W7CE" <>
>To: <>
>Subject: [TowerTalk] Horizontal tower movement at the top
>Date: Sun, 6 May 2007 14:20:36 -0700
>Does anyone know how much horizontal movement is considered acceptable at
>the top of 100' tall Rohn 25G, 45G and 65G towers?  I don't see any mention
>of it in the Rohn catalog.  I know that the tops move, I just don't know 
>much is considered normal.
>I'm considering a rather unusual tower installation at my QTH.  Because of
>large trees that occasionally lose branches during wind storms and property
>line constraints, a guyed tower isn't practical.  For years I've had my 3
>element yagi on top of a 95' Doug Fir tree and it has worked well there.  I
>watched it during our record setting wind storms last winter and the top of
>the tree was only moving about 6-7" (less than the diameter of my Ham IV
>rotator).  This is a big tree with a 42" diameter base and an 8" diameter
>stump at the 95' level where the antenna is mounted.  The problem with this
>installation is getting up to the antenna to do maintenance, plus I'm
>planning on replacing it with a new SteppIR as soon as I figure out how I'm
>going to mount it.  What I'm thinking about doing is installing 100' of
>tower as close to the tree as practical (less than 3') and attaching it to
>the sides of the tree with angle iron at 20' intervals.  With this 
>I don't think the tower could ever come down unless the tree itself did
>also, which is unlikely based on our soil type and the excellent health of
>the tree.  I would then mount the antenna on the top of the tower.  This
>would give me a much easier way to climb up to the top.  I can use 25G, 45G
>or 65G for the installation, whichever would be best.  25G would be the
>easiest to install because of it's weight and I suspect that it is the best
>I'm looking for opinions on the viability of this solution.  Will the
>movement of the tree in the wind stress the tower too much or will it about
>the same amount of movement that a guyed tower would normally experience in
>a big wind?  Opinions?  Suggestions?  Am I thinking a little too far 
>the box?
>Clay  W7CE


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