Scott wrote:

AJ Lake wrote:
.

I'm sure that our (US) military protects for EMP, but I doubt it is by
using tube equipment. Likely something more modern. Fancy Shielding?
Perhaps you know the technology currently used?

Nope, no idea. When I was in the Air Force working on aircraft comm
radio equipment, "they" told us if a nuke went off, our radios would
most likely not work. I don't think fancy shielding would work since
all radios I know of have a hole in the shield where RF and EMP can
enter. It used to be called the antenna port. Not sure what they call
it in "modern" equipment...

I did some work on simulated EMP back in the 80's (when I was wearing a
different engineering hat), and we found that there's /nothing/ that will
protect semiconductor equipment against it.

We used very high voltage discharges (at the City University High Voltage
Lab in London), and we destroyed all sorts of gear! The original plan was
to examine resilience against lightning discharges, but later on the
experiments were expanded to cover EMP. We found that "hollow-state" gear
could withstand quite a lot of abuse and continue to work, whereas the
solid-state equipment would die at the slightest provocation. This
had /very/ serious ramifications for the "defence industry".

I've recently found another application that's best serviced with valves
("tubes" - U.S.). A friend of mine is responsible for the maintenance of a
number or airport NDB units. The ones they had were solid state, and would
quite regularly get fried by static or lightning. Over the last few days
we've begun the design of a valve replacement for the "hot" end of these
things. It's not difficult to get a few tens of Watts at MF with valves!

Bob