Well they aren't standard Vacuum tubes that you have in say an audio amplifier. They are miniature tubes with a lot better MTBF than standard tubes.
We (Sweden) used them in our cold war fighter J35 and we had lots of these planes flying up until the 1990: ies.
I guess we used them for the same reason that the Russians did in the MIG25, at the time (60: ies) it was the only thing that could be manufactured domestically.
It is of course better to use silicon based electronics but the vacuum tubes did its job.
On the matter of Russian "low-tech" the big difference is perhaps the reliability and the MTBF design targets.
Many Russian parts and planes are designed for a low MTBF.
As far as I understand the reason for that is both technically, tactical and political.
1 Technical, having a low MTBF as a target means you can build it cheaper and easier.
That also means you can build more for the same amount of money.
2 Tactical, producing parts like a jet engine with a low MTBF is easier so you can use less skilled workforce.
But more importantly, they run the factories with a wartime productivity output schedule even at peace time, so in case war breaks our there is no adaptation time needed for the factories.
4 Political, having factories producing a high output of parts and goods for the military in peace time was desirably for the Soviet Union as it was foremost a “state for the worker”
In choosing between producing expensive parts that lasted long and gave less jobs - and producing inexpensive parts that lasted a short time so you could employ more people, the choice was easy.
Western states have a different view on military munitions and are focusing more on reliability and state of the art technology.
So you have the “cheep and plentiful” and on the other hand “expensive and complicated” doctrine.
The high-tech doctrine isn’t necessarily better than the low-tech, it’s just a different way of doing things.
Regards
//deBug
