On Sun, 6 Mar 2005 13:41:05 +0100, "LA7GIA - Ken"
wrote:

I plan to use some of the trees at my QTH as a tower. I have to parallell
trees that is apx 50'. At the top they will be abt 15'' thick. They are
spaced 20'' which makes it easy to build a ladder so that I can climb up. I
plan to build a metal plate and install a rotor on the top of the parallell
trees, so that I can turn my 15' boom lengt 3 el 20m yagi beam. This tower
would be very cost effective.

Of course I am aware of the potential problems regarding maintenance etc,
but does anyone have experience with this kind of tower? Will it be stable,
what abt guying etc. Comments is welcome before I settle this project.



Assuming you are talking about two parallel trees, not trees grown
together all the way up, I don't think you will have the results you
expect. The trees WILL sway towards and away from each other and
destroy any means of connecting them together. If you were to use one
tree, you might get away with mounting the antenna there.
Unfortunately on a windy day your antenna is subject to being whipped
to pieces as it not only gets hit with the wind at it's natural speed,
but also as the tree whips it back against the wind increasing the
wind load to as much as two to three times or more.

I have never mounted a beam in a tree, but I have mounted verticals at
the tops of trees. I have never had to go up and bring down one of
those verticals. Relative to some of the trees I used, you have a
short tree and if it's fat enough, it may not sway as much.

I would test your theory with an inexpensive or throw-away antenna
first before setting up your beam.

Good luck.

--
73 for now
Buck
N4PGW