Original poster: "Jim Mitchell" <Wrenchead-at-starband-dot-net> Hi, I assembled a plasma tweeter using an EL509 tube, and when I heated up the filament and connected the B+, I got nothing, no noise, no corona. The tube got warm, which is a sign of it working properly, but why isn't it oscillating? Does the 100uh inductor really make a difference? I am using a 120uH inductor. Regards - Jim Mitchell