VALVE TESTER

A valve tester is an instrument for evaluating the performance of radiovalves, also called radiotubes, or vacuum tubes. These testers are expensive pieces of equipment because there are not many around. I have therefore built one myself. My tester has a number of sockets for most common types of valves that were produced between 1920 and 1970. Instead of built-in meters it requires an external voltmeter and an external milli-amp meter. The high voltages for the anode and the screen grid are generated internally and these can be varied. The heater current and the variable negative voltage for the control grid are provided by two external low voltage supplies.