This page http://www.futurescience.com/emp/emp-protection.html talks specifically about radios, but it says transistors in faraday cage are more resistant to EMP than vacuum tubes.
The big fallacy about radios in faraday cages being invulnerable to EMP is sort of hypothetical. Completely isolated, yes possibly. However, it is not a ‘radio’ if it can’t pick up anything (i.e., without using a transmission line to an antenna). It is here through this path that it becomes vulnerable and requires a lot more thought about mode and method of protection.