Topband: Vertical Lightning Protection
Missouri Guy, N0TT
n0tt1 at juno.com
Wed Jan 5 12:41:59 EST 2005
Impressive antenna you have there!
> I have had a large
> vacuum variable capacitor
> in place to do the job for several years, but lightning took its
> last spring. I thought I had
> ample protection...a 350uh choke across the base insulators to drain
> off static build-up,
OK, that's good
> three sets of spark-gap balls; one on each tower leg across the
> insulators. This worked well
> through many storms.
I would use *pointed* spark gap hardware vs the round ones.
Electrical charges tend to accumulate where the curvature of a
conductor is greatest. So, a pointed object would have the
greatest curvature vs a round one....that's why lightning rods
are shaped the way they are.
> I have another vacuum variable ready to mount;
> 800pf @ 18 kv, 150 amps.
> Any ideas on how to keep this beauty from falling prey to Mother
Set the spark gaps as close as you can without arcing under normal
transmitting voltage. Protect the gaps with a rain hood.
Other than shorting out the capacitor when it's not in use, there
isn't much else one can do. Mother Nature does what she wants! :)
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