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Re: [TowerTalk] Horizontal tower movement at the top

To: <>
Subject: Re: [TowerTalk] Horizontal tower movement at the top
From: "W7CE" <>
Date: Mon, 7 May 2007 19:24:48 -0700
List-post: <>
No joke!  It was a serious question and I was hoping for some serious answers.  
Specifically, how much movement is normal for the top of a 100' Rohn 25G tower.

Clay  W7CE
  ----- Original Message ----- 
  To: ; 
  Sent: Monday, May 07, 2007 2:12 PM
  Subject: Re: [TowerTalk] Horizontal tower movement at the top

  >You have got to be kidding! April Fool's Day was over a month ago!!


  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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