Our former DE was satisfied with old-fashioned lightning rods & saw no
reason to add any of thes fancy new-fangled dissipaters. But I once saw a
demonstration by Lightning Master, Clearwater, FL -- Maybe Tampa, now. they
had a Van DeGraff Generator sizzling away. Then he just simply opened one of
his dissipaters, which looked kind of like a 1" paint brush with stainless
"bristles." The sizzling stopped immediately, even though the dissipater was
several feet away.
But good grounding is the most important thing. That station with the
multipoint dissipaters was struck so often I couldn't keep the station up.
While the multiple points help dissipate the electrostatic field so there
will be lower energy in any lightning stroke, the tower will also be more
likely to be struck. I had to leave it off for about a week, until an order
of ground rods arrived & we could drive a few into the sugar sand. I never
say "IF lightning strikes the tower..." Rather, I always say, "When
lightning strikes..." When you have a tower sticking up higher than anything
else for miles around, you're certainly going to be struck. But rather than
worrying or giving up, as some do, we need to design a way to quickly
conduct 25,000 -- 50,000 amps into the earth. And then everything survives &
it's not a big deal.
Here's one last thought: I bought a ground adapter from Polyphaser, to
connect flat copper strap to a round Heliax line. The spec sheet stated the
maximum resistance of their adapter was 0.007 Ohms -- sounds good. Then I
began thinking... If there was 10,000 Amps passing thru that adapter,
10,000 X 0.007 = 70V. I like to use 10,000 A as an estimator because it is
an easy number for my simple brain to comprehend, even though an average
lightning bolt carries much more current. So:
50,000 X 0.007 = 350 V.
Even with the thing "grounded." I could be killed by touching it at the
moment lightning hit the tower!
It changed the way I lean against the transmitter or racks...
On Wed, Jul 14, 2010 at 11:36 PM, Steve Tuzeneu <email@example.com> wrote:
> If you're in Florida, perhaps you're using the Gila-Stat? I recommended
> them at an A.M. station and it cut down damage to equipment substantially.
> Steve Tuzeneu, C.B.T.
> Manager-Engineer, Announcer, Webmaster, IT Support
> Member: Society of Broadcast Engineers
> Independent Contract Engineer
> G.R.O.L. (FCC License)
> N1XXE (General Class Amateur Radio License)
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