Triode

I got some boroslicate tubes to make some ampules. After realising how fun it was to work the glass, I got some tungsten wire. It wasn't long before I was able to get a consistent hermetic seal. So at that point the only logical step was to try and make a triode.

Making it

I started by blowing out the glass tube to make the envelope. This was difficult as I didn't have a powerful enough torch to heat up a larget enough area, not a glass lathe to keep things round.

One design choice I made was to use a titanium sheet as both the anode and the getter. This kept the number of components to a minimum.

The grid was a a coil of stainless steel wire, and the filament was a strand of tungsten wire.

The getter did flash pretty well. I was able to get most of the deposits on the glass off by heating the glass with a blowtorch so it would evaporate and condense futher down the evacuation tube.

Testing

I was able to light up the filament with ~1W at ~3V. The anode was at about 20V with a 10k series resistance. And I was able to see the grid voltage modulate the current flow.

Unfortunately I got a little excited with the filament power and burnt out the filament before making a proper trace of the tube.