“Back during the Cold War there was a Russian pilot who flew one of their leading edge MiG fighters into an airbase in Japan and defected.”
“Among other things, we discovered that the Ruskies were still using vacuum tube technology.”
There is a theory that they used vacuum tubes to protect against EMP pulses. The MIG-25 wouldn’t have been vulnerable to them.
After finding out they used a stopwatch mounted to the analog instrument panel on the Soyuz to time retro rocket and re-entry engine firings, surely, someone gives them far too much credit for something that would have been a dumb luck discovery. Just because the tubes were in the systems, does not say that all systems were tube based.
“There is a theory that they used vacuum tubes to protect against EMP pulses.”
So then,,, my ‘56 Fender Pro Amp will still work if we’re hit by an EMP pulse attack? Cool! If there’s any electricity.
My first steps in electronics were done with vacuum tubes. Transistors were around, but I just didn't have access to them for experiments.
In 1970's there was nothing wrong with using a tube-based radio. Many people when hearing "tubes" are probably thinking about something like this - big and fragile. But in reality by that time subminiature tubes already existed, and they were very competitive with early transistors. They easily operated into VHF (and later all the way into millimeter wave,) they were resilient to EMP, they had low noise, and they could be manufactured in any quantity on simple equipment. My first receiver was using just one tube, and it worked very well. You couldn't do that with a single transistor of that era; its h21 sucked, and it was all over the map. Development of ICs led to invention of many reliable and repeatable circuits that threw transistors at the problem; in the end we got the OAs of today, as well as other BJT and FET based analog circuits.
Of course today the quantity converted into quality. Modern DSP-based radios cannot be implemented with tubes. But in 1970's it was a very reasonable, albeit conservative, solution. Today vacuum tubes remain the only viable candidates when you need at least tens of kW of RF power, and when you need lots of power at lots of GHz. Tubes like TWT are operating on unique principles and are offering incredible gain. Tubes called "magnetrons" are powering all our microwave ovens - and plenty of radars. Tubes are not dead yet; semiconductors are doing very good in small signal environment, but they have nothing to offer when you need a 100 kW (V)HF amplifier. Solid state PAs exist for 10 kW, for example; they use power combiners; I worked with those, but the cost of them may make them uncompetitive when the tube-based amplifier needs only one or two glass or ceramic tubes.
Mig-25 was far from being that much an UFO hi-tec thing but vaccuum tubes were there on purpose.
First reason it was an extremely fast Mach3 aircraft. Flying that fast means a lot of heat from air friction. Semi-conductors and microchips as a more advanced alternative to tubes aren’t 100% reliable in that environment.
Second reason it was designed to repell a first strike with B-58 and B-70 bombers. It means operations in a conditions of a nuclear exchange. And vacuum tubes are absolute immune to EMP effects.
Third reason Mig-25 was a huge bird. It could easily carry heavier tube electronics.
At the end it proved a pretty effective even decades after phased by original users.
Iraqi’s claim Mig-25s radars had a nice range and easily burned through jammers. It is rumored Mig-25 had a first kill in a Gulf Was (USN F-18).