[TowerTalk] grounding elevated vertical for lightning?

[Jim Lux]

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.