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Re: [TowerTalk] Looking for a light coaxial

To: towertalk <towertalk@contesting.com>
Subject: Re: [TowerTalk] Looking for a light coaxial
From: Rob Atkinson <ranchorobbo@gmail.com>
Date: Sat, 12 Sep 2020 05:20:33 -0500
List-post: <mailto:towertalk@contesting.com>
It's a fixed non-rotatable wire beam.  A balanced antenna.  Feed it
with balanced line.  Light weight ladder line in the 400 to 600 ohm
range.  You can use AWG 16 stranded.  No baluns, significant loss,
heavy coax or other coax nonsense.  Connections and splices can be
done with banana plugs and jacks and split bolts.  Save the unbalanced
line for shack use and feeding UNbalanced loads such as 80 or 160 m.
monopoles.  How long is your feedline run?

You'll need a balanced link coupled matching network which is easy to
build or buy, and a way to bring the line into your transmitter room
but that's all fairly easy if you don't freak out and give up.

Now, if you are unable to wrap your head around anything other than
unbalanced line, then I'd look at 3/8 inch foam dielectric heliax.  I
think it is much easier to work with than the LMR stuff and it doesn't
weigh much.  I'd make a 180 degree turn with it at the feed point by
making it do a half loop up and down to the balun to make it harder
for water to wick up into the foam if there's ever a leak.   This also
provides strain relief.   But remember, balanced line removes a lot of
issues like high loss due to band edge high vswr on the line.   If the
run is several hundred feet long then I would not consider coax at
all.

73

Rob
K5UJ
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