• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

mercury vapor rectifier tubes on e-bay

I've got some 866's, they are cool tubes, other than the warmup, which is a little pain to design in.. no big deal though.

that and theyve gotta be choke loaded, etc.

I'm not sure if the glass used is opaque to UV, or if it lets it through... don't want to be burning my eyes out
 
This tube is a half wave rectifier tube which take 2.5V 5A for the filament. I would rather go with the 83 rectifier tube instead.

With this kind of mercury vapor tube, please don't forget to add a standby switch for delaying the HT applied to the tube. It needs some warm up time.