Uploaded July 2025 | Updated September 2026, 3 weeks ago
Collected a few old cathode ray tubes lately. The video looks at some of the features of these tubes and how they power up. There is a bonus at the end of a recent failure. I was trying to measure the cathode current with acceleration voltage on an old CRT, but the tube wasn’t very responsive and a flashover occurred at the gun when the operating voltage was almost 4 time the designed running potential. Strangely, this fused the heater in the cathode rendering the tube useless. Unfortunately, the camera angle was bad and it completely missed the flashover. I did have a GM counter and I didn’t notice any perceivable x-ray emission either.
Collected a few old cathode ray tubes lately. The video looks at some of the features of these tubes and how they power up. There is a bonus at the end of a recent failure. I was trying to measure the cathode current with acceleration voltage on an old CRT, but the tube wasn’t very responsive and a flashover occurred at the gun when the operating voltage was almost 4 time the designed running potential. Strangely, this fused the heater in the cathode rendering the tube useless. Unfortunately, the camera angle was bad and it completely missed the flashover. I did have a GM counter and I didn’t notice any perceivable x-ray emission either.
