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Re: [TowerTalk] feedpoint choke for inv L

To: towertalk@contesting.com
Subject: Re: [TowerTalk] feedpoint choke for inv L
From: David Gilbert <xdavid@cis-broadband.com>
Date: Sun, 18 Nov 2018 23:49:21 -0700
List-post: <mailto:towertalk@contesting.com>

I've never understood the value of a feedpoint choke for a typical ground mounted vertical antenna, Inverted-L  or otherwise.  Putting the choke at the base of the vertical section doesn't change the fact that the coax typically runs right next to the radials, thereby either experiencing coupling to the radials or simply being an extended radial itself, depending upon how you want to look at it. If you put the feedline choke out at the edge of the radial field it's not going to do any good anyway since for typical radials that are roughly 1/4 wavelength long that's a current node.

I suppose there might be some useful decoupling effect of putting a choke a half wavelength away from the feedpoint, but even then I'm not sure what it is.

Anybody want to take a crack at explaining why it's worth the bother?

Dave   AB7E



On 11/17/2018 10:45 PM, Wes Stewart wrote:
No.

On 11/17/2018 7:40 PM, Jamie WW3S wrote:
I have an Inv L for 160, currently fed with a bulkhead SO-239 attached to a radial plate.....is there some sort of Balun/feedpoint choke that may work better?
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