I often have SurvivalBlog readers write to ask me about vacuum tube technology and its robustness in EMP and CME events, and which antique multi-band vacuum tube radios to look for. I'm also asked how to determine which models can be run on both AC and DC power.
To begin, vacuum tubes are inherently "hard" to EMP and CME but not invulnerable. They are also relatively safe from lightning strikes--but again not invulnerable. Modern integrated circuits are at the opposite end of the scale for vulnerability. In essence, the smaller gates in a microcircuit, the greater its vulnerability. In recent years, chip makers have been creating chips with gates smaller than .3 microns. They are very vulnerable! In fact just an inadvertent discharge of static electricity can destroy a chip.