[BC] EMP - SS versus thermionic finals

[Gary Peterson]

" I have seen tube transmitters severely damaged by lightning and I
believe either flavor requires proper lightning protection.  As for EMP,
I am not a sure as you that even a tube TX could survive that.  The
transmitters that will survive are the ones completely off line not
connected to an antenna of a power source. A few stations have such an
arrangement.
Remember with both lightning and EMP what does not come down the antenna
can come in through the AC supply which is solid state regardless of the
RF amplifier technology.
R "

In the eighties, my company sent me to put an old AM, that they had just
bought, back on the air that had been dark for several months.  This station
had, at one time, been a cog in the Conelrad wheel.  The transmitter site
had a 1240 Conelrad transmitter, generator, with large fuel tank, and a bomb
shelter.

I found some large boxes from the Federal Government, containing all manner
of diagrams and parts to modify the phasor, ATUs and electrical service
panel.  Obviously, this stuff had never been installed.  There were lots of
sealed spark gaps, discharge tubes, MOVs and bonding straps.  I surmised
that some of the atomic bomb tests in the 40s and 50s revealed what was
necessary for an AM radio station to survive an EMP (electromagnetic pulse)
from a nuclear detonation.  There were no solid-state transmitters, that I
am aware of, in, say, 1960.  I bet there are people on this list that
installed the EMP kits back then.  I would be curious to know if these EMP
kits helped significantly with lightning induced problems.

Without the necessary precautions, I suspect an EMP will leave your tube rig
in the "toast" category.  The firebottles will survive but lots of mica
capacitors may short out.  In an unprotected solid-state rig, the PN
junctions and mosfets would become blown fuses.

Gary, K?CX