Mike Knudsen wrote:

I doubt there were ever walk-in tubes. The vacuum required for any kindof tube
life is so "hard" and pure that you wouldn't be able to pump out a whole room
to that purity. Though maybe with a really big "getter" ... Mike K.



I don't know about walk in tubes but I do recall visiting a UK Post
Office radio station many years ago and walking into the final
amplifier where there was at least one tube which I recall as being
around 4 or 5 feet high (maybe more) which had a water cooling system.
If it means anything to anyone the station was at Leafield in
Oxfordshire.

Dave