I always enjoy the beauty of vacuum tube, especially when the heater is glowing bright on thoriated tungsten tube and in a dimmed room. The photo below only taken for fun. I power up the EIMAC 8165/4-65A tube with 4x AA battery. The 6V filament glows, but I think due to limited current from the AA batteries, it can’t be as bright as normal. But even with the limited current, we still can enjoy the beauty of it…

More EIMAC tubes to follow… 😉