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Re: [TowerTalk] The Vertical and the Balun

Subject: Re: [TowerTalk] The Vertical and the Balun
From: "Rob Atkinson" <>
Date: Thu, 15 May 2008 18:29:58 -0500
List-post: <">>
I also try to avoid using a balun (1:1 unun...whatever term you wish) as
much as possible.   They seem to be okay when they match up  with the
parameters of the system they are placed in and these don't change much (but
how often is that?), or there are added antenna or feedpoint components that
keep them within an acceptable impedence range for a change in
frequency.     I've seen too many baluns in the wrong places generating heat
more than anything else so I prefer to keep the banance of my antennas and
their feedlines the same (however I have no rotatable balanced antennas).

I don't know about vertical monopole noise pickup with an unchoked
unbalanced line but my experience with a large wound feedline choke on 160
was that it was unnecessary in preventing common mode RF--I removed mine and
never missed it.  I figured I had enough radials on the ground that the
return current on the outside of the feedline was too small to be a
problem.   I'll have to a choke again to see if it helps reduce noise on
160--anything to get my S9 noise level down would be welcome.

BTW, without top loading or hanging a wire off the top to make an inverted
L, I'd try to keep a stragiht base fed vertical (no coiils) on 160 m. to at
least 1/8 w. (45 degrees).   Even then you may have some  difficulty
matching to a 50 ohm line and operating at QRO power levels.  The gap
voyager is 45 feet tall, i.e. < 45 degrees, but employs almost every trick
in the book:  linear loading, stubs, capacitor, capacitance hat, bottom side
of the dipole extensions that trail out over the ground....there has got to
be some loss with that antenna on 160.


rob / k5uj

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