Grid Voltage News Today

My article last month covered the history of AVO valve testers and described the seven different types that were made over the years and how they worked. I also have some general advice about repairing and calibrating these instruments. by Ian Batty

“I checked it on the AVO.” For decades, AVO valve testers were the standard for testing valves (their multimeters were also extremely popular). This article explains the differences between the various AVO meters and describes how they work. by Ian Batty