On 7/8/2013 10:21 AM, Pete Smith N4ZR wrote:
I'll take those odds, and repeat - unless you are prepared to spend
totally disproportionate amounts of money, or have the EE smarts to do
it yourself, and the physical circumstancesto do everything optimally,
you are begging far more hurt by staying connected.
For every lightning hit 10 miles from a storm, there are probably a
thousand that are well forewarned. If you're looking to protect the
Space Shuttle, that's one, thing, but...
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 7/8/2013 10:07 AM, Stan Labinsky Jr. wrote:
I have to chime in too.
This idea of only connecting the antenna & control cables when you're
going to operate and not relying on a properly designed and
implemented protection system begs hurt.
There are stories, presumably documented, of people being struck by
lightning from a storm ten miles away, in an area that did not appear
to be at storm risk... bright, sunny and clear.
And how often do we get so into what we're doing that we tune out all
else, including our spouse calling "dinner"?
Russian Roulette states that everybody who plays gets shot... eventually.
Stan
-----Original Message----- From: Jim Lux
Sent: Monday, July 08, 2013 9:28 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Lightning protection
On 7/8/13 5:28 AM, Pete Smith N4ZR wrote:
My answeris simple - It is not cost-effective. They are using
extensive lightning grounding at the tower base, and purpose-built
transmitter
buildings with elaborate grounding systems. 24/7/365 costs.
You have to remember that THERE IS NO 100% EFFECTIVE LIGHTENING
PROTECTION even for the 24 X 7 stations. Many times I've heard them get
knocked off the air. So even if you copy a commercial installation, you
still should disconnect everything from everything and ground the coax
to the rigs which are unplugged from the mains.
IOW you want to disconnect from everything that goes to the outside
world. Telephone, cable, electrical power, computer networks, USB and
serial cables, and anything in the shack with more than a foot or two of
wire connected to it.
Don't forget, a strike a mile away can induce as much as a thousand
volts per meter of wire and that's enough by itself to take out a lot of
equipment. Disconnected equipment has been destroyed and there was one
example posted here a couple days ago. It's rare, but can happen, but
the safest method is to have a good ground system and STILL disconnect
everything.
Study the manuals on grounding already mentioned, as an improperly
installed system MAY be worse than none at all and disconnect those rigs.
Some of us have elaborate ground systems with nearly as much in the
grounding as the antennas, BUT any of our results are still purely
anecdotal.
73
Roger (K8RI)
Exactly..
They are also facing a very different cost/benefit analysis than the
typical ham. They pay a LOT more for the assembly and construction
labor than most hams do, so something like using AWG 2 instead of AWG 6
doesn't make a lot of difference in the overall construction cost.
And, their "cost of non-availability" can be substantially higher. If
an FAA control tower is off the air, that's a big problem and it gets a
lot of attention.
ask me whether a direct strike while connected would result in <5 volts
That's the other thing. Equipment designed for 24/7/52 kinds of usage
tends to be more rugged, and it tends to be "single frequency"...
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|