Topband: Vertical Lightning Protection

Phil Clements philk5pc at tyler.net
Wed Jan 5 01:19:22 EST 2005


My 160m vertical is in a ground plane configuration. It consists of 
199' of Rohn 25 tower.
The insulators and radials are at the 60' level. The radials are 110 
degrees long and the
139' radiator combined result in self-resonance on 1635 khz. This 
requires a series capacitor
at the feed point to move resonance to 1830khz. I have had a large 
vacuum variable capacitor
in place to do the job for several years, but lightning took its toll 
last spring. I thought I had
ample protection...a 350uh choke across the base insulators to drain 
off static build-up, and
three sets of spark-gap balls; one on each tower leg across the 
insulators. This worked well
through many storms. 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 
Nature?

Thanks in advance to all!

(((73)))
Phil, K5PC





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