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.
73,
Dave
wa3gin
----- Original Message ----- From: "Jim Brown"
<jim@audiosystemsgroup.com>
To: <towertalk@contesting.com>
Sent: Sunday, February 10, 2013 1:52 AM
Subject: Re: [TowerTalk] grounding elevated vertical for lightning?
On 2/9/2013 12:43 PM, Mark Robinson wrote:
Could he not also ground through an rf choke to bleed off static?
Lighting is NOT a DC event, it is an RF event. Chokes block it
(until they fry). Not a solution. As AC0C noted, the coax is
grounded at the house/shack, as it must be, which provides a DC path
anyway.
As W8JI has observed with respect to several other problems of this
nature, we must consider the entire system. The length of the coax
matters a lot -- a long run of coax has a lot of inductance, so it's
close to an open circuit for lightning.
Jim Lux got it right -- a spark gap to a local rod does the job for
lightning and doesn't degrade the antenna system.
73, Jim K9YC
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