[Milsurplus] How Much Vacuum in "Vacuum Tubes?"

[Horace W. Hall]

>
At any rate, it seems plausable to build one's own vacuum tubes, if one was
really desperate and had no other source.
>

I seem to recall reading a few accounts in really-old radio magazines of a
few people making homebrew tubes, back when the audion was still a new
invention. They would have been directly heated cathode types, & apparently
they did work to some degree. Performance specs were whatever luck
provided. 
--Wayne 
  WB4OGM