DCAudioDIY.com

Here is a lady that scratch builds tubes.
Actually she is building a 1920's designed tube amp but makes the tubes first.
This is real DIY
https://youtu.be/-UEfqAWb3fE

_________________
Walt

In order to do this there are three things you need:

1. Glass blowing ability (don't inhale)
2. A good vacuum system
3. A knowledge of Cathode chemistry both for directly and indirectly heated cathodes.

The killer is number 2. The National Capital Astronomer's Telescope Making Class at the Chevy Chase Community Center has a vacuum system that is good enough to Aluminize telescope mirrors. I don't know if that is good enough to evacuate tubes. You would need a system with a roughing pump, a diffusion pump, and a cold trap. I do know someone who could answer questions about cathode structures and chemistry if you couldn't find the answers online.

This should also be of interest -

https://hackaday.com/2018/12/31/the-art ... brication/

When making high power electronic flash tubes, we used liquid nitrogen on the cold trap.

Back in the 30's and 40's dry ice and I think acetone was what was used. Liquid Nitrogen is probably safer and better. For indirectly heated cathodes I think high purity Mike of Magnesia is used.

_________________
Walt

I can't spell. Milk of Magnesia.

More details -

https://hackaday.com/2018/12/31/the-art ... brication/