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Re: [TowerTalk] Balun on a vertical

To: Dave NØRQ <n0rq-lists@sbcglobal.net>,"Towertalk Reflector" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Balun on a vertical
From: Jim Lux <jimlux@earthlink.net>
Date: Mon, 09 Oct 2006 09:25:44 -0700
List-post: <mailto:towertalk@contesting.com>
At 08:12 AM 10/9/2006, Dave NØRQ wrote:
>Or, even on a vertical with elevated radials, if there are "enough"
>radials, does it really matter if the feedline acts as just one more
>radial?
>
>On my 40m vert, there are about 20 elevated radials, about 10'
>above ground, and the feedline also comes out at about the 10'
>level.  Since the feedline is about 200' long, is feedline radiation
>really an issue in this case?


Only if you are obsessing about making the 
vertical performance match a theoretical model.

There IS a potential problem with the "coax as 
just another radial" and that is that since the 
coax usually goes places radials don't, you might 
get RF in places you'd rather not have it.   And 
that goes both for RF radiated from your antenna 
or for interference that winds up IN your feed system.

I had a problem with what appeared to be RFI from 
a network cable coupling to the outside of a coax 
line and then into the antenna. Cat 5 wire and 
coax were bundled together going up to the 
roof.  I did away with the network cable, and all 
was better.  Didn't bother to track it down any further.

I suspect that some RFI filtering would solve 
this sort of problem quite nicely, and I have a 
box full of nice lossy toroids now.


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