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[Towertalk] Tree Mounts

To: <>
Subject: [Towertalk] Tree Mounts
From: (
Date: Fri, 6 Sep 2002 20:16:45 EDT
In a message dated 9/6/02 5:00:39 PM Pacific Daylight Time, writes:

> Does anyone out there have any experience with mounting a rotatable yagi
>  to a tree?  I've been told this is (or used to be) common in the Pacific
>  Northwest.  I'd be interested in hearing:
>     1) How to calculate a safe load

    Calculate? How would you come up with a formula for the tree capacity? 

    I've installed 14-15 antennas in trees including HF yagis and 2L 40M 
beams so I have a professional perspective but don't have any numbers to show 

    I usually top the tree when it's about 10 or so inches in diameter. How 
strong is an 8x8 piece of wood? Pretty danged strong actually. 

    If you're talking about an HF beam, I wouldn't go any larger than about a 
16' or so boom - the forces just get too big.

    The other limiting factor is rotator capacity since I pipe mount the 
rotator and then the antenna on top of it. I prefer the T2X since it has a 
lot of mast mounting capacity and will twirl just about anything small to 
moderate in size for a long time. 

>     2) How to fabricate a suitable mount

    I use a piece of galvanized pipe (1-1/2" ID = 1.9" OD) with a horizontal 
piece welded to it (picture a cross). The horizontal ends are bolted to the 
tree as is the vertical pipe. The rotator goes on top of the cross. I use 
1/2" lag screws on the vertical pipe - 3-4 of them - and screw them right 
into the tree. The antenna will blow away before the mount fails.

    A BIG advantage for a tree installation is that it's UNREGULATED when it 
comes to building departments! I charge a lot for them because they're dirty 
and a lot of work. 

Steve    K7LXC
Professional tower (and tree) services for commercial and amateur 

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