[time-nuts] Lightning arrestors for GPSDO antenna

Chris Albertson albertson.chris at gmail.com
Thu Oct 16 21:27:01 EDT 2014


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 <dgminala at 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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-- 

Chris Albertson
Redondo Beach, California



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