This is a tubetester from the USA, so it operates on 115V. I use an original Weston transformer for it. It tests for leakage resistance and gives the also the mutual conductance Gm in umho. It tests magic eyes, normal tubes, thyratrons, diodes, regulators ect. The cabinet has a paper roll with all settings for most tubes. But it is easy to test tubes that are not listed if you have the datasheet. Every socketpin has one switch. The numbers relate to the functions, so if you have a Heater on pin 4 and 5 you put switch 4 at 6 and switch 5 at 7.
The platevoltages are up to 250VDC, but there are also a few AC voltages.