Here are some further comments re Jim's info regarding possible use of
pulleys to overcome the effects of sap and tree growth.
1. Method #1 is to simply haul a pulley with a line through it up to the
correct height. Tie off the line holding the pulley and forget about taking
it down after sap and tree growth consume the rope over the branch. This
method works well for antennas whose ends are supported by trees.
2. Method #2 is more complicated, but solves a problem that arises if you
need to hold the center of the antenna up midway between two trees. I have
this situation with a Carolina Windom whose center needs to be held up by a
large branch, high up in the air, which was conveniently near where the
center support point was.
After you get your line over the appropriate branch you can then carefully
pull 3 or 4 separate lengths of fishing line over the branch. Then, and
this is the fun part, carefully weave a separate length of 1/16" Dacron line
into a secure knot around the limb. This line will have a pulley on it and
the pulley will have your larger 3/16" Dacron line running through it. You
can do this by using one fishing string at a time to repeatedly pull the
Dacron line around the limb, crossing the lines each time so that the Dacron
line is secure on the limb with the pulley hanging underneath. You can yank
the fishing lines and break them off after the last pass.
At this point you have a pulley at the right spot and your antenna haul rope
through the pulley. There will be no way to get the pulley down but that
doesn't matter, and neither does sap or tree growth. Your pulley will be
secure and there will be no abrasion of the rope that holds the pulley, as
there otherwise would be.
You have to sort of guess at the correct length of the 1/16" line so that
you can get several turns around the limb and still have the pulley hanging
down a few inches below the limb.
You will have to give this some thought to see how it works. I can tell you
that it works well. It is surprisingly easy to do once you get the initial
line over the right spot. You do have to be very systematic. It is best if
you don't try this on a windy day.
I have tall pines and large oaks that wave in the wind. I have never had an
antenna come down using either of these methods.
------------------ Wes Attaway (N5WA) ------------------
1138 Waters Edge Circle - Shreveport, LA 71106
318-797-4972 (office) - 318-393-3289 (cell)
Computer Consulting and Forensics
-------------- EnCase Certified Examiner ---------------
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of jim Jarvis
Sent: Monday, October 19, 2009 10:16 AM
To: Michael Ryan; towertalk@contesting.com
Subject: Re: [TowerTalk] tree strung dipoles
I have 1/8" olive drab dacron line which I favor. For longer term
installations,
I also have some 1/4" o.d. dacron. Have used both with a low
profile carolina windom
here in NJ.
I bought some 1/8" kevlar line, black, as well, but find that's a bit
stiff and
heavier than the dacron. As a result, it's harder to get launched.
My technique is to use a fishing arrow and game-tracker system.
The game tracker
string is 15 lb test. Depending on tree height, this may get you a
direct from
game tracker to 1/8" dacron transition... for taller trees, you may
need to use some
intermediate string... and I bought a reel of mason's string from
Home Depot for $5 which
serves that purpose.
Based on experience, I've settled on #12 insulated flexweave wire as
my standard,
and have run up to 1.2 kw without end insulators, by simply tying a
loop in the wire,
and another in the dacron line.
One caveat: When working with pine trees, the sap will glue the
rope to the tree,
resulting in real stress on the antenna. It will be nearly
impossible to pull the line from
the tree, if you want to take the antenna down. Thus, in this
situation, I would favor
use of pullies.
Up in VT, I had a 160m windom held up by 1/4" o.d. dacron, between
two 140' pine trees.
Came time to bring it down for some maintenance. I wound up having
to tie a turning block
to a line at the base of the tree, and run a line down to my jeep,
100' away. I backed down
the driveway a reasonable distance, heavily tensioning the line.
Then, suddenly, it went
slack.. as a branch came down from on top, 4" in diameter!
The damned dacron rope
was embedded in the thing by almost 1/2", and glued fast with sap.
The mass of that branch coming down from 100' would have killed
anyone under the tree.
Appropriate caution is advised.
N2EA
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