As a curiosity, I will mention that the 6c33c lamp is still used in some aircraft (MIG 25) today why? Because the lamp is resistant to 'electro magnetic pulse', I like this lamp very much and a lot of audio constructors use it. Not to mention oil capacitors. And ending with measuring equipment that is almost indestructible.
In the photo I noticed that one lamp broke ![Cry :'(](https://www.eevblog.com/forum/Smileys/default/cry.gif)
That EMP theory is mostly an urban legend.
Realize that MIG25 was designed in the late 50s, with the first flight in 1964. So the reason the tubes were used in the MIG25 is simply because nothing else was available. Transistor has been invented only in 1947 and reliable mass-produced transistors did not arrive until late 60s/early 70s - and that was in the West,
That was not my experience in Australia, where by the early 1960s, solid state was well established,in both consumer & commercial comms equipment.
"Hybrid" designs offered most of the advantages of both types of technology.
In my employment prior to 1965, I watched the transition in car radios from normal tubes with solid state HT inverters, through "low voltage" tubes with solid state audio output stages to all solid state.
In the same time period, battery operated solid state "home" receivers had a short "vogue", replacing the all tube "mantel radios" of the then recent past.
As soon as people realised that the "home" receivers were just portables in a different box, they faded away.
In 1965 I went to more technical employment, initially for a short while at a TV Studio, where there was a reasonable amount of solid state stuff, although tubes still dominated.
I then went to a Broadcasting/HF Comms site.
On the Comms side, we had a hybrid solid state/ tube 1kW self tuning HF transmitter, & later, another, not so sophisticated hybrid HF transmitter.
In 1967 I went to Wyndham, a "cow town" in the East Kimberley region of tropical Western Australia.
The equipment there which was my direct responsibility comprised :-
Tnree "hybrid" HF transmitters, three fully solid state HF receivers, six "Vogad" transmit/receive devices (all solid state) , & comprising the link to the nearby town of Kununurra, two fully solid state VHF (around 160MHz) 2 channel links, (both ends), two fully solid state 4 channel UHF (around 500MHz) links (both ends).
This equipment was several years old at the time.
It seems that the military did lag, somewhat, though.
I read an article a few years back,(effectively a "teardown") on the radios used in the Mirage IIIs which went into service with the RAAF in the '60s.
These were full of tubes!
It seems that the clunky old "Postmaster General's Dept" was more forward looking than the Air Force!