[R-390] TUBES

[Bill Hawkins]

Other tries at this thread revealed that the home tinkerer
might be able to build (or rebuild) an 01-A class tube with
a "soft" vacuum. IF he or she could get coated filament wire.

The tubes that we want are all hard vacuum tubes. It takes
an expensive set of vacuum pumps to get down to where flashing
the getter takes out all of the molecules left.

Making the elements for a 7 pin miniature pentode seems to be
impossible without expensive tooling - kinda like making a
turbo-pump for a Saturn V engine. Both materials and tools
will be prohibitive for short production runs.

And then there are the glass seals for the pins ...

Regards,
Bill Hawkins