" . . relatively lightning-free coastal Oregon . . ."
Well, that bit of information is true (http://www.lightningmaps.org is a
great site to monitor). One of the hams up in Lincoln City feeds into this
system. On very rare days we may experience some sheet lightning but I've
not heard of anyone on the coast experiencing a tower strike. Most tower
grounding I've seen here on the coast is unsophisticated compared to some of
the systems you folks are posting.
On the ocean side of the OR Coast Range, if you are going to camp, better
bring dry wood with you!!!!! When we retired we had looked at land to the N
of Cuba, NM as a place to live. Hummmmmm, maybe the old wet and cool OR
coast wasn't a bad choice. No heat issues here!! We had a heat wave here a
week ago, temp got up into the mid 60's.
As to corrosion and rust, I quickly learned every local source and not so
locally for SS, corrosion resistant Al and corrosion blocking compounds.
Much of the knowledge base on all of this comes from the marine outfitters
for the fishing/crabbing fleets in ports such as Newport, Charleston and
Astoria.
Where ever you live, there is always something one has to deal with.
Don W7WLL
-----Original Message-----
From: Dick Blumenstein
Sent: Tuesday, July 26, 2016 9:36 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Does prevailing grounding scheme promote large
ground loop
Steve-
May the force be with you... (or should I say, it appears the force is
with you TOO MUCH!).
(Sigh... when man makes plans, G-d laughs.)
Sorry for all your troubles.
I have no idea what I'll be facing here in the western foothills of NC.
I'll find out, though; I'm sure.
PS - If you move to Oregon, then all your connections and equipment
might corrode/rust!
Dick, K0CAT
======================
Steve London wrote on 7/26/2016 9:37 AM:
K9YC wrote:
The problem with this (and any) analysis of a lightning event is that it
is FAR more >complicated than anything we can compute, simply because the
voltages and currents induced >in any system (stuff wired together) will
be different in each conductor depending on >WHERE the strike is, the
physical geometry of the conductors that make up that system, how >energy
from the strike gets to the earth, etc.
I can attest to that ! In 13 years of living on a dry, New Mexico hilltop,
I have learned a lot about mitigating lightning damage. Frankly, the cost
and effort of doing lightning protection "perfectly right" is prohibitive.
The approach I have settled on is simple disconnection to keep the bulk of
the lightning energy out of the house. All RF and control cables to/from
the towers (I have 3 towers, with 5 rotator controls and a number of
remote antenna switches) terminate on a bulkhead panel about 30 feet from
the house. During lightning season (May-October), everything is
disconnected at the panel, except when I am on-the-air. All AC power to
the ham shack is disconnected, except when I am on-the-air (unplugged - I
don't trust the small air gap in switches and relays). Yes, this makes it
inconvenient to be on-the-air during the summer. Even with these measures,
I have learned the hard way about interconnectedness (K9YC's "stuff wired
together"). A nearby or direct hit to a tower will destroy USB ports on
computers and radios, if they are interconnected with a USB cable. I have
tried commercial USB optoisolators, but have found they generate too much
RF noise. The latest incident was earlier this week. I had a direct hit.
The only "stuff wired together" was an Astron power supply, connected to a
2 meter radio. Just before the storm, these were working fine. I unplugged
the antenna from the 2 meter radio, and the AC power from the power
supply. There was still a 3' long power cable connecting the power supply
and 2 meter radio. After the storm, the power supply blew fuses. The root
cause was a fried LM723 in the power supply, causing the voltage to go
high, and the crowbar protection to be activated.
Sometimes I think moving to relatively lightning-free coastal Oregon would
be a good idea !
73,
Steve, N2IC
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