<< Anyone have any safe and fairly effective ideas on launching dipoles
into trees? <snip> 73, David Jones, KK7GW >>
David,
This method is a heckuvalot cheaper and a lot more fun.
SETTING LINES IN TREES FOR WIRE ANTENNAS
The two most common methods are to use a slingshot or a bow to shoot a
light line over the desired tree or branch with which you can pull up a
heavier line, with which, in turn, you can pull up your wire.
Some thoughts to consider:
1) It's very difficult to raise the feedpoint of a dipole up into a tree.
The legs will catch on every branch, and working them up into the tree can
be *surprisingly* difficult. A better method is to install a sky rope
across the tops of two trees, with a pulley and working line tied on at a
point between the trees with which you can pull your dipole feedpoint up
and down for service.
2) With much less work, you can pull a single length of cheap, insulated
wire over or through one or two trees to form the biggest inverted delta
loop that you can. Then, bring the two ends together at the bottom, just
out of harm's way overhead, connect a 300 ohm "TV twinlead" feedline or
450 ohm ladder line, and run it to your tuner (one that has an internal
balun and accepts open wire lines). Then, you have completely sidestepped
the problems of trying to raise the free ends and feedpoint of a dipole up
through tree branches, and you end up with an antenna that would probably
outperform the dipole.
3) In either case, you still need to shoot some line. I read a lot of hint
?n' kinks before trying and developing the following method, which has
been very successful with trees up to 85' in height. I feel that there is
enough reserve power with a full draw, depending on your slingstot, for
even higher trees.
Materials needed:
1) Wrist rocket slingshot.
2) Several 2 ounce, round sinkers, with swivel eyes built in (you will
lose one from time-to-time), painted day-glow orange or green.
3) 50-100 yards of 20 pound test monofilament fishing line, depending on
how high your trees are.
4) One wayward, orphaned, or abandoned traffic cone, slightly used,
appropriated using the method of your choice ;-D.
5) Some motor oil, any weight.
6) Antenna rope on a spool. Braided polyester is best, such as that sold
by The Radio Works, Inc.
7) Electrical tape.
Cut the top off of the traffic cone, leaving a tapered section about 10
inches tall on the base. Tie one end of the line to a small hole in the
base flange. Wind the line onto the tapered section. There is a trick to
this to prevent the line from twisting so much whenever you wind the line
onto the cone. Wind 5-8 turns while facing the free, outstretched line,
then turn your back to the free end of the line and wind the same amount
of turns. Keep alternating, and you will cancel out the twists in the line
that result from your winding.
Now that you have all your line on the cone, cut a small slit it the top
of the cone to jam the free end into to hold it. Pat the line down with
the motor oil and rub it in so that all of it is lubricated. Now you have
created an open-faced reel that will pay off line behind your sinker with
very, very little friction. The oil may sound like overkill, but it also
helps the line slip freely through tree branches and leaves, which can
make the difference between a successful shot and a hangup.
Pick your tree or branch. You will find it easy to select your spot and
hit it because there is so little drag on the line from the reel that the
trajectory of the sinker is hardly affected. Tie on your sinker with a
barrel knot (ask your fishin' buddy about this anti-slip knot for
monofilament), load up yer shootin iron (oops, I mean slingshot), tilt the
cone slightly in the direction of fire with your toe or some other prop
under the base, and let ?er RIP! You will be amazed at how well you can
place your line. You will probably overshoot your tree the first few
times! You won't always need a full draw. Once the sinker clears the upper
branch or top of the tree, get ready to reach out to the line that is
paying off and start slowing it down. The sinker must be allowed to keep
enough momentum to pull the line all the way back down. This is where the
oil really helps.
Did you make a bad shot? No worries, cut the sinker off the line and
wind the line back onto your reel, always alternating your turns. You will
most likely snag your line and lose your sinker if you try to pull it back
through the tree without cutting it off. Once you get the shot you like,
cut the sinker off and tie the line onto the free end of your antenna pull
rope. Tape over the joint to form a short taper from the heavier antenna
rope down to the monofilament. This makes a big difference when the knot
has to pass over a small branch.
Put a section of pvc pipe or broomstick through the center of the rope
spool and have a friend hold it so that it will pay out freely. You can
also use jack stands to hold your spool, or just have your friend pay it
out from a coil. Pull the monofilament back over the tree, and your rope
with it. Once you get the rope end back down to your side, cut off the
monofilament, and walk it away from your cone, stretching it out on the
ground before you wind it back up. If you just drop the free end and try
to wind it up, you're stuck in tangle city!
Now you have something you can really pull with to raise your wire! Good
luck!
--...MARK_N1LO...--
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