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Re: [TowerTalk] Horizontal tower movement at the top

To: "Pat Barthelow" <>, <>,<>
Subject: Re: [TowerTalk] Horizontal tower movement at the top
From: "W7CE" <>
Date: Mon, 7 May 2007 19:38:47 -0700
List-post: <>
Garry was kind enough to send me some photos of his installation last 
summer.  We met at Visalia last year and discovered that we had similar 
antenna installations.  My Cushcraft A3 has been up in this tree at 95' 
since 1984.  Garry's mounting approach is very nice, but it has the same 
problem that I'm trying to eliminate from my current installation.  Climbing 
a tree that is 42" around at the base and doesn't have branches for the 
first 50' is very challenging.  It takes the professional arborist that I 
use over an hour to get to the top.

As mentioned in some of the other posts, the tree has not gotten any taller, 
only thicker.  If you measure the stump diameter at the very top of the tree 
it hasn't changed significantly in 24 years.  However the base of the tree 
is about 3-4" larger in diameter.  Over time the taper of the truck will 
become more and more pronounced (this is a common technique used in Bonsai 
to intentionally achieve a very tapered trunk).  If I space the tower  12" 
from the base, the tree will grow into the tower sometime in the next 
100-200 years.  It's likely that I won't care by then.  In the meantime, I 
figured that I could check and relocate the mounting brackets every few 
years as needed to keep the tower plumb and to prevent the tree from growing 
completely around the brackets.

Thanks & 73,
Clay  W7CE

----- Original Message ----- 
From: "Pat Barthelow" <>
To: <>; <>; <>
Sent: Monday, May 07, 2007 1:43 PM
Subject: RE: [TowerTalk] Horizontal tower movement at the top

> 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:
> Best,
> 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 
>>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 
>>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. 
>>watched it during our record setting wind storms last winter and the top 
>>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 
>>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 
>>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, 
>>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 
>>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 
>>the same amount of movement that a guyed tower would normally experience 
>>a big wind?  Opinions?  Suggestions?  Am I thinking a little too far 
>>the box?
>>Clay  W7CE


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