I also have a shack on the 2nd floor and I also disconnect all cables
going to the tower. I only use the station for major contests so doing
this is not really inconvenient. Disconnecting however is not a reliable
means of protection as the energy can be induced into anything nearby. I
am not sure if there is any way to stop this from occurring. Even if you
disconnect it is a good practice to have multiple lines of ground rods a
single point ground and MOVs or GDTs on every rotator and relay.
John KK9A
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Lightning Protection
From: Pete Smith N4ZR <n4zr@contesting.com>
Date: Fri, 05 Jul 2013 15:44:07 -0400
Every time Towertalk starts off on one of these threads I feel compelled
to add one skeptic's viewpoint, and this time I'm actually going to do it.
Unless you are an electrical engineer with deep understanding of lightning
protection, I think that attempts to replicate a commercial 24/7
always-connected solution are far more likely to fail than to succeed.
Rhetoric about causing all the grounds in a station to rise and fall
together during a strike is fine, but how much voltage difference does it
take to damage ICs and semi-conductors?
I am *not* that engineer, so I decided 17 years ago that my installation
would have quick-disconnects for every conductor coming from the tower, at
the panel where they enter my second-floor shack. I leave them
disconnected except when I am on the air. I should probably have the
disconnects at ground level, but I felt I would be more likely to
disconnect them if they were right at hand.
A few years ago, I took a direct hit on the top of my tower, some 190 feet
from the house. I was in the shack at the time, and the SO-239 connectors
on my entry panel arced with a loud bang. Both rotators, a stackmatch and
a remote antenna switch were damaged, and a loading wire on my 40-meter
yagi was severed, but the only damage in the house was to two computers on
an Ethernet network, both of which were fried by induced voltage on the
network wiring, and my telephone answering machine. I was well pleased
with this result, as was my insurance agent.
73, Pete N4ZR
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