On Mon, 19 Oct 2009 11:16:20 -0400, jim Jarvis wrote:
>Based on experience, I've settled on #12 insulated flexweave wire as
>my standard,
Flexweave is a TERRIBLE choice for any antenna that must withstand the
high physical stress of swaying trees. I've put up a half dozen antennas
built with Flexweave. ALL of them have broken within a year, some
sooner.
#12 solid copper should be considered a minumum for this sort of
installation, and #10 copper is better. I use plain ordinary THHN (house
wire). Equally important, every element of the dipole must be quite
robust. The Alpha Delta center insulator, and the one that The Wireman
sells are the ONLY ones to consider. The RadioWavz are AWFUL. I bought
two to try -- both broke apart with only the weight of RG8X coax pulling
on them.
I've used a lot of the antenna rope that DXEnginering and others sell.
It's quite robust, BUT it does NOT hold up to abrasion -- if the
protective outer jacket wears (from movement on a pulley or over a
branch) it WILL break. W3DQ recommends rope sold by the RF Connection. I
haven't tried it yet.
Bungee cords are also a TERRIBLE idea -- sunlight will rot them in a
year or so. Weights are a much better solution. Some use old window
weights. I didn't have any, so I made weights by filling big water jugs
with dry sand. The jugs cost about $13, the sand about a buck, and the
weight is about 90#. This works well for my 200 ft spans between trees
at 100 ft with antennas fed with RG11. Lighter, shorter antennas require
less weight.
Be sure to use a good, big pulley. As I recall, Frank, W3LPL recently
did a presentation to PVRC on this topic. I haven't seen it, but I'm
sure it's worth finding.
Yes, the pneumatic launcher is a winner. K2RD brought his to my QTH and
cleared the top of my tallest redwood (170 ft) by a good 10 ft on his
first shot.
73,
Jim Brown K9YC
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