On Thu, 17 Nov 2011 16:38:50 +0000 (UTC), Peter Irwin
wrote:

In rec.audio.tubes dave wrote:
On Thu, 17 Nov 2011 07:34:03 +0000, Geoffrey S. Mendelson wrote:

They showed some promise in the missile and space exploration systems of
the time, because transistors could not stand the temperature extremes
or cosmic radiation they would be exposed to. That also did not last
long, as improved "space grade" transistors came out.


Cold Cathode tubes were voltage regulators, displays, etc. I have never
seen a cold cathode amplifier.

I think the tubes being referred to are field emission triodes and
various microwave tubes. You can certainly make a linear amplifier
with field emission devices.


Valves in space have probably finally met their match with Gallium
Nitride. It is pretty radiation-hard, and capable of valve-type power
outputs.

d