[HCARC] Lightning Protection

[Kerry Sandstrom]

Anything in a transmission line has loss.  Connectors, connector adaptors, 
splices, filters, limiters, etc all have loss.  At HF and with good quality 
items, the loss is negligible.  Losses increase if the SWR on the line is 
high.  For lightnig arrestors, connectors, and adaptors the losses should be 
a tenth of a dB or less, probably impossible for a ham to measure.  Be sure 
you check the maximum rated power and the maximum allowed SWR for the 
lightning arrestors.

Next, I am not a fan of lightning arrestors.  I don't believe any of them 
will protect you from a direct lightning strike.  You have to provide 
someplace for the energy to go once it reaches the lightning arrestor.  This 
means a heavy ground strap and a real ground, not just a ground rod driven 
into the ground.  I have never used a lightning arrestor.  Instead, if I'm 
not on the air, my equipment is disconnected from any outside 
antennas.Whenever I'm not using the rig, it is disconnected.  Yes, I connect 
and disconnect all the time, but its a lot safer than trusting a lightning 
arrestor and associated ground system.  My HF antenna is a vertical and the 
feedline is buried RG-8/U type cable.  About 100 feet of it is buried.  I 
believe the lightning will find a route to ground and destroy the cable in 
the process and the rig end is outside the house with nothing connected.

I have had some experience with lightning.  When I lived in San Antonio 
during the 70's there was a lightning strike in my neighborhood.  What I 
lost in this strike was the silicon bridge rectifiers on two solid state 
TV's and the RF amplifier on a Radio Shack Time Cube.  The bridge rectifiers 
were connected accross the AC power line in the TV's.  I'm convinced the 
pulse from the lightning strike came in the AC power line to the TV's.  I 
replaced the rectifiers and the TV's ran for many more years.  The Time Cube 
has a pull up rod antenna.  That was the only antenna on the Time Cube.  In 
this case, the electromagnetic pulse generated by the lightning strike 
coupled into the Time Cube abd "fried" the RF amplifier transistor.  I 
replaced it with a 2N2222 and it worked fine.  Incidently, I had also 
"fried" athe RF amplifier by touching the antenna with my finger on a cold 
dry day.  It was sensitive to static.  For the record, my equipment then was 
vacuum tube from the 50's and 60's.  It was very rugged.  It was plugged 
into the AC line and the normal interconnecting cables were attached and it 
survived unscathed.

In summary, I believe disconnecting is the least expensive, yet best 
solution to the lightning problem.  Even with lightning arrestors, you still 
need to be concerned with the AC power line and any wires attached to the 
rig.  Lightning is essentially a naturally occurring EMP and all the 
precautions one takes for EMP protection, one needs to take for lightning. 
These include shielded cables, shielded connectors and power line surge 
suppressors.

Before anyone thinks I'm an EMP fanatic, let me assure you I am not!  I am 
quite familiar with the relationship between EMP and lightning and I'm also 
quite familiar with the protective measures required, and I believe they are 
not practical for amateurs.  Only my Uncle has to take the risk, however 
small, seriously.

kerry