I heard that equipment that uses vacuum tubes are generally less susceptible to electromagnetic pulses than those that employ solid-state devices.
I don't know if its true, because I didn't find any detailed research about this topic.
If its true, is this because of the physical size difference between these devices, or is there another reason?
I searched about this subject, and I found an article from the Science Magazine.
I searched for the relevant parts, and it says:
Most important, the U.S. military itself had not experienced problems, since most of the field equipment and ships exposed to EMP dated from the 1940's and 1950's, their electronic systems relying on vacuum tubes.
In the 1970's, it was discovered that vacuum tubes have about 10 million times more hardness against EMP than integrated solid-state circuitry (2).
As you can see at the end, it references another article:
M. A. King et al., An overview of the effects of nuclear weapons on communications capabilities," Signal (January 1980).
After 2 hours of searching for this article, I couldn't find any traces of a Signal magazine or anything like that, released in the 80's.
I found other citations of the same article, and it has the additional author not present in citation part of the Science article, P. B. Fleming, but still, no info on these guys apart from people with the same name but entirely different professions and other irrelevant research papers.
I have some doubts about the science behind the claim that vacuum tubes are 10 million times more resistant against EMP, it kinda sounds like an advertisement from that time.
Broad, William J. - Nuclear Pulse (I): Awakening to the Chaos Factor
Science 29 May 1981: Vol. 212, Issue 4498, pp. 1009-1012