[high_vacuum_house]

Good evening,
On going through a box of secondhand telly valves I found a Mullard PC92 valve with balls of metal rolling around inside. Looking through the glass between the lower mica and the base it can be seen that a major flashover had taken place inside. One leg of the heater where it enters the cathode has been vaporised completely and its connection to the base has melted back nearly to the glass. The cathode strip to the base connection has almost disappeared and blowing a small hole in the bottom of the cathode tube where it had been welded on.

I Bet this valve lit up rather well during its demise. Surprisingly the vacuum is still there! I wonder if it went heater to cathode short with no fuse protection.

Has anyone seen any valves that have this much punishment in their collection?

Christopher Capener