"Richard Harrison" wrote
Coax rejects common-mode
lightning energy. We used zero protection across coax and never had a
burnt transistor receiver front-end.

Richard, could you please explain the term "common mode lightning"? I've
seen you reference that many times and meant to ask what that is. Apparently
an uncommon mode burned through 300' of RG8 (literally melting the end
connected at the radio) and disintegrated the internal coax post inside a
Drake R8B.

I sent the radio to Drake, and they explained that the lightning protection
inside the radio was literally exploded, but it did it's job and the radio
was easily and inexpensively repaired.

The coax in question was disconnected about 150' from the house, but
lightning apparently jumped from the tower feed across a foot of air space
and back into the PVC pipe channel housing several coax, which led to the
house. The Drake was the luckiest of the second-story ungrounded shack gear.
The protecton on this particular installation was multiple radial-grounds
from the base of the tower. It was a very nasty strike or set of strikes, as
several outbuildings on the property all suffered equipment damage. _Maybe_
this was a case of ground current from the strike jumping into the coax, but
in any case several coax carried very high charges into the home.

Jack