I recently got a 5 cm high radio tube from a old radio in my house. It has 9 pins ,arranged in a C shape at the base, a getter at the top and parallel metal plates inside. I decided to use my GMC-300E plus ,Geiger counter to check if it had a thoriated cathode. It did not. Just for fun, I two of it's pins to a 1 Kv power supply. I expected a nice show of plasma inside the tube. When I turned on the supply ,purple eruptions came from the plates. The Geiger counter was still on and sitting beside it. The Geiger counter's display whited out and the light at the side which flashes when the counter registers a click, just glowed constantly, the buzzer did the same. I instantly moved the counter away and turned off the supply. What made the counter do this? Was the tube interfering with the Geiger counters circuits, which seems unlikely. Or was the tube emitting an amazing amount of X-Rays ? The supply was only 1 Kv so this seems impossible.