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Re: [TowerTalk] grounding elevated vertical for lightning?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] grounding elevated vertical for lightning?
From: Jim Lux <jimlux@earthlink.net>
Date: Sun, 10 Feb 2013 12:37:55 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 2/10/13 12:11 PM, Jim Brown wrote:
There are two elements to the protection. First, the coax shield is
bonded to the panel and from there to the rest of the ground system.
Second, the gas tube shorts the center conductor to the shield, which
limits the voltage at the equipment input.

73, Jim K9YC

On 2/10/2013 7:49 AM, David Jordan wrote:
Jim,

Isn't part of the Polyphaser lightning protection circuit a spartgap?
I opened one up and thought I saw a gas tube.


yes, a gas tube is basically a calibrated spark gap that fires at some voltage.
The question *I* would have is whether a gas tube can take a 10-50kA 
pulse.  I'd make a spark gap out of something like angle iron at the 
antenna, and let the gas tube take care of the residual transient at the 
shack end.
A 1/10" uniform gap will fire at 7kV... once it fires, though, the 
voltage drop will be around 100-150V.
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