I have 80 ft trees that are used to hold up several antennas.
I have used 2 methods.
The most accurate is a Drone that I have used for years that was built from
a parts from Hobby King and the Wii controller. I use a servo to pull a
pin that allows the payload to drop. It can easily lift enough weight to
pull a 15 pound kevlar fishing line over the tree, but I have found that
you have to fly at least twice as high as the tree to allow gravity to do
its work. From there, I pull back the poly binder twine and then I use
that to pull the final antenna line, usually some sort of UV protected
Kevlar. You can't do this with a $40 kids drone as it won't lift enough
weight and it just scary to fly. I had pictures of me doing it in
published in QST many years ago (maybe 6-8 years ago).
My next go to is an Air Cannon that fires a payload of 2 AA batteries taped
together and the same 15 pound fishing line. I find this to work well
enough, but it can go a little further than I want to go considering I am
dealing with a forest. It takes about 50 psi to fire the payload over the
80ft trees without effort. The batteries are in a 1/2" pvc pipe (I
think... I built it a long time ago). In Canada, I got most of the parts
are a local hardware store, but Harbor Freight int he US should work just
fine.
My inverted L goes between 2 trees and I now have a small bullet block at
the apex of the L with 10ft of UV protected shock cord holding the block.
At the end of the antenna, another 10ft of UV protected shock cord is used
to ensure that swaying trees in 40 knot winds do not destroy the antenna.
I find this works very very well.
My biggest problem with the 160M with elevated radials is that the
resonance point of the antenna can vary about 40khz depending on if the
ground is frozen or not. When it is frozen, the resonance point slides up
the band. Once thawed, it moves back down. I find that I have to add
about 6ft to the antenna in the winter and then take it out in the summer.
Mike va3mw
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