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Re: [TowerTalk] 43ft Vertical Feeding Question and Balun type

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 43ft Vertical Feeding Question and Balun type
From: "Dan Zimmerman N3OX" <n3ox@n3ox.net>
Date: Thu, 20 Nov 2008 12:08:32 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
"So my simple question is "How are YOU feeding your 43ft vertical?""

Matching networks.  Gets around all feedline loss issues:

http://www.n3ox.net/projects/lowbandvert

But I don't even use that one anymore, now I'm doing 60 feet:

http://www.n3ox.net/projects/sixtyvert

That said, if you use very low loss feedline and use the right balun, on
SOME bands feedline loss can be quite minimal with the 43 footer. (80m would
still benefit greatly from *proper matching to the feedline)  But even on
the bands where feeding a 43 footer through an ideal 4:1 balun shows it
would work, you have to be careful about the actual balun.

For what it's worth, I recommend reading the eHam thread someone else
referenced if you're looking for a balun.  A true 4:1 current balun is
actually probably not what many people are using (though it would work fine
if they were) and it was determined in the eHam thread that one popular
transformer used at the feedpoint of a popular antenna should be rewired as
a 4:1 UNUN instead of a 4:1 voltage balun.  The difference is subtle and the
fix very easy, but it could make a significant performance difference for
many folks.

If you're running a 4:1 balun on a 43 foot vertical, open up the balun box
and read the eHam thread and you might get to be a little bit louder ;-)

As far as best efficiency, the devil is in the details of feedline and
balun...

If you want to add a matching network for a band you feel weak on, you might
find these a useful starting point:

http://n3ox.net/projects/lowbandvert/matching_networks.pdf

73
Dan
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