Thanks, Chris.
I've done a bit or research on the subject, and think I have a reasonable
grip on the necessary steps. I have an 8' ground rod driven into the ground
directly under the spot where my antennas mount. #6 solid copper from the
rod to a heavy aluminum plate, where the arrestors will be mounted. A #6
solid copper wire from the plate to the antenna mounting structure.
I will also have an arrestor at the antenna input of each GPSDO unit, which
will be mounted on a 2" wide copper strap, which will be then run to the
outside ground rod with a doubled 1" wide copper braid.
I realize that extremely low ground resistance is fantastic, but I don't
have access to a ground resistance set, so I'll have to accept what I have
and accept the consequences if something happens. A second ground rod isn't
out of the question, but will have to wait until my broken wrist heals so I
can swing a sledge hammer.
I'd still like to hear comments on the effectiveness of gas discharge type
arrestors.
A question has bothered me for a while, but can't find a definitive answer.
Should I enclose the antenna feedline in metal conduit or nonmetal conduit?
I've seen documents that state that metal conduit is the best way, and
others stating that metal conduit shouldn't be used Anyone have a good
answer (talking about antenna feedline; not the grounding wire)?
Thanks,
Dave M
---------------------------------------------------------------------------
Chris Albertson wrote:
Lightening arrestors are an important part of a protection system but
just installing some in the antenna cable is not going to help so
much. You need a system approach. If you do it right you can take a
direct hit
The big problem with grounding is Ohm's Law. That is if any current
flows in a conductor that has resistance there will be a voltage
across the conductor equal to the current times the resistance. But
with lightening you can have 100,000 amps of current in a ground
wire. If that wires has
0.01 ohms of resistance you have 1,000 volts above true ground on your
"ground" connector on the lightening arrestor. Your ground is no
longer at ground.
You need some very tiny resistances and to get that you are going to
need to do things like using multiple ground rods and large
conductors. And connecting grounds together.
On Thu, Oct 16, 2014 at 4:34 PM, Dave M <dgmin...@mediacombb.net>
wrote:
I'm looking for effective coaxial lightning arrestors for my GPSDO
antennas.
I've seen several types; those completely enclosed in a one-piece
metal enclosure (no replaceable components) and those having a
replaceable gas discharge tube seem to predominate the list.
I'm looking closely at the gas discharge tube types, and am curious
as to their effectiveness and durability. I'd like to know stuff
like; are they effective in dissipating a static charge, how do I
know when the gas tube needs to be replaced, are the gas tubes of a
special type, are replacement gas tube easily available, etc.
I'm interested in opinions and experiences with arrestors and
recommendations for which type is most effective.
Thanks for comments,
Dave M
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Dave M
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