Re: [TowerTalk] grounding elevated vertical for lightning?

[K8RI <K8RI-on-TowerTalk@tm.net>]

On 2/10/2013 3:11 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.
Plus I think the inductance of the coax, the internal capacitance and 
capacitance  to ground will substantially lower the voltage by the time 
it gets to the device at the entrance compared to the base of the tower.
73

Roger (K8RI)

> 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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