This argument has always had holes, as far as I am concerned. It is not the
strike energy that "Bleeding" will handle, but the static charge that helps
create an ionized path, that the strike can follow. Diminishing that path
HAS to help.
Additionally, I know this is not absolute; I merely want to improve the odds
a little. Other protection is also needed.
----- Original Message -----
From: "David Gilbert" <email@example.com>
Sent: Sunday, August 01, 2010 11:35 AM
Subject: Re: [TowerTalk] Vertical antennas and lightning
> Look at it this way ... the magnitude of arcing you get across the end
> of the coax if you don't have the antenna DC-shorted to ground is rather
> tiny. My experience over the years (when I had a dipole or vertical
> that was not DC-shorted to ground) was that I'd get a spark across the
> end of a PL-259 (roughly half inch spacing) every few seconds. Add up
> the energy from all those little arcs over maybe a ten or fifteen minute
> period and compare it to the energy from a single lightning strike.
> Then consider the likelihood that the portion of the cloud system that
> generated the lightning strike wasn't even near your QTH ten or fifteen
> minutes ago.
> It's like trying to drop the level of a flowing river by removing water
> with a teacup.
> DC-shorting an antenna to ground is important to protect both equipment
> and people from static buildup. I once drew a really thick (lots of
> current) 2 inch long bright blue arc to my left hand from the shack end
> of the coax coming from an unterminated 80m dipole (my right hand was on
> the floor) ... that calculates out to about 300,000 volts and the biceps
> of both arms were sore for three days. Imagine what the energy that is
> capable of generating those half inch arcs might do to a receiver front
> end or the contacts of a small relay.
> But grounding the antenna isn't going to even come close to bleeding off
> enough charge from the clouds overhead to prevent a lightning strike.
> Dave AB7E
> On 8/1/2010 8:40 AM, Bill Aycock wrote:
>> In your message to Dan, you say:
>> "you'll be draining off the static electricity (DC charge) to
>> ground, hopefully thus minimizing the likelihood of a strike to begin
>> I have always believed this to be true, but whenever I even hint at it,
>> someone on this reflector jumps on me. Do you have a reference for me?
>> From: "Gene Smar"<firstname.lastname@example.org>
>> Sent: Friday, July 30, 2010 5:40 PM
>> To: "Dan Schaaf"<email@example.com>; "Tower and HF antenna construction
>> Subject: Re: [TowerTalk] Vertical antennas and lightning
>>> If the inductor is the correct value (high enough XL at the
>>> lowest frequency of operation so as not to upset the feedpoint impedance
>>> appreciably) you can permanently connect it to the feedpoint. In that
>>> configuration you'll be draining off the static electricity (DC charge)
>>> ground, hopefully thus minimizing the likelihood of a strike to begin
>>> I'd recommend XL> 10 X 50 Ohm = 500 Ohms at the lowest frequency.
>>> 73 de
>>> Gene Smar AD3F
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