[TowerTalk] Lightning Protection Question

[Gary Schafer]

Simple spark gaps are not so simple. Temperature, humidity, contamination by
dirt etc will all make a difference on what voltage they arc at. Gas tubes
are much simpler and more reliable for repeatability of breakdown voltage.

With a spark gap you have the problem of discontinuities in the line (swr)
where the bulky gap is installed. Gas tubes can also be a problem in getting
the proper enclosure to maintain a constant impedance to the line. 

It is much simpler to buy a ready made device such as Polyphasers where all
that work is done for you. But you can do it yourself.

73
Gary  K4FMX

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Roger (K8RI)
> Sent: Sunday, September 12, 2010 11:11 PM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Lightning Protection Question
> 
> 
> 
> On 9/12/2010 8:54 PM, Jim Miller wrote:
> > Jim
> >
> > Any construction examples anywhere on the net of the non-sparkplug
> approach?
> > Sounds interesting.
> >
> All you need are two pointed conductors. One for the ground side and one
> for the center of the coax.  They can be just that simple, or you can
> machine a fancy coax connector with adjustable points.    The conductors
> should be heavy enough to stand a pretty good jolt, but they can be
> sacrificial.  Just use your imagination.  Two points and two conductors.
> 
> 73
> 
> Roger (K8RI)
> > 73
> >
> > jim ab3cv
> >
> > On Sun, Sep 12, 2010 at 1:21 PM, jimlux<jimlux at earthlink.net>  wrote:
> >
> >> You can get non-resistor plugs. I've used them as vacuum HV
> feedthroughs.
> >>
> >> As a spark gap, they'd work ok, but a couple pieces of sheet metal
> might
> >> be easier and more compact.
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