This French Centrad tube tester was made in 1951 in Annecy (France). This model is equipped with two cylinders that combine the selectors for 300 different tubes. There is documentation for more than 1000 tubes. In addition to normal reading of the cathodic flow on the dial, this device allows precise flow reading on an external multimeter. Photo no.3: test of an EL84. Other conventional functions: filament continuity, internal short circuit, cathode flow, cathode isolation.