in case of a nuke attack (far more likely than an EMP), the valves'
shell will shatter. you are better off storing your regular
transceiver inside a thick copper box with an 'rf tight' lid.

instead of EMP-proofing the transceiver from inside, EMP-proof it from
the outside.

your best bet would be to use a 7MHz CW transceiver with 5 watts
output. This will give you consistent communicability with reasonable
power to get through. More power will drain your battries (or your
legs, if u are pedalling a generator) faster. Avoid FETs and MOSFETs
in your design, stick to bipolars. also avoid ICs, use discrete
transistors, store a few spares in a bag inside the transceiver. have
soldering iron handy too, u might have to repair quite a few things.
you will also need an antenna tuner and a long wire.

this is a pretty grim discussion. in 1999, my country(india) and
pakistan were on the brink of war. my city was considered a high value
target. i have lived these thoughts far too close to comfort. there
are no nuclear shelters in india save a few for the president and the
prime minister etc. thinking back about those days, i find it ironic
that i thought that i would personally survive an nuclear attack and
have enough sense left to get on with establishing a wireless station.

- farhan