This is a truly rare tube tester from the French radio manufacturer Radialva.

Tube testers were essential devices that played a crucial role during the era of vacuum tube technology. Imagine a radio repairman a century ago, standing in a workshop or store, testing vacuum tubes with a device that looks like a mix between the dashboard of an old airplane and a magician’s prop.

These testers allowed for a quick assessment of tube quality, making them indispensable not only for repair technicians but also for manufacturing plants where tubes were tested before being released to the market, installed into devices, and so on. The technician would simply insert the tube into the designated socket, turn a few knobs, and then watch as the needle indicated whether the tube was “good” or “bad.” It was almost like a medical check-up for vacuum tubes—if they passed the test, they were ready to continue their life in radios, televisions, or amplifiers.