Theo’s tester design performs static and dynamic tests on power valves, enabling matching and diagnosis of faulty valves. It is not a precision instrument, but does give a clear picture of valve conditions and enables monitoring of emission loss over a period of time. If necessary, small signal valve testing can also be incorporated. This valve
tester can also detect microphonic and noisy small signal and power valves. An article about this valve tester was published in Electronics World magazine dated January 1998.