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Re: [TowerTalk] Feedline (choke) question

To: "[TowerTalk]" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Feedline (choke) question
From: Brian Beezley <k6sti@att.net>
Date: Fri, 26 Sep 2025 12:10:20 -0700
List-post: <mailto:towertalk@contesting.com>
Here's another offbeat idea. If you have an effective grounding point nearby, you may be able to shunt unwanted residual shield current to ground. The coax need not be severed. However, I would not trust my skill at making a watertight connection to the shield after slitting the outer cover to get at it. And what if the spot is not near a good ground? An alternative would be to install two quarterwave wires perpendicular to the coax. Lay them on the ground. To avoid a direct connection that exposes the coax to the weather, wrap the center of a halfwave wire around it to capacitively couple the two arms. The wire would need to be lengthened to maintain resonance. This is a single-band system. I don't think I'd want this up in the air, but if it was on the ground in a spot without foot traffic it might be OK. I'd model it and as much of the RF environment as I could using realistic ground constants to see how well it might be expected to work in a particular situation. On the other hand, if the coax was on the ground it might be worth the trouble to install connectors and a choke.

Realistic ground constants:

https://k6sti.neocities.org/hfgc

Brian

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