This very gassy 280 is on the tube tester. The filament is set at 6.3 volts, too high for an 80 but required to get this kind of light show from a very gassy tube. Needless to say, this tube would be a disaster if it were installed in a radio.
The purple glow is a good indicator of gas in the tube. Normally this would be contained in the area between the hot cathode and the plate. But in this tube a small aurora is generated as I switch sides, energizing first one plate then instantly switching to the other. Don't ask me why I tried this, and, of course, don't try this at home without proper adult supervision.
The purple glow is a good indicator of gas in the tube. Normally this would be contained in the area between the hot cathode and the plate. But in this tube a small aurora is generated as I switch sides, energizing first one plate then instantly switching to the other. Don't ask me why I tried this, and, of course, don't try this at home without proper adult supervision.
Another of my favorites, a very gassy 224.
Don't confuse the deep BLUE glow clinging to the outside of the plates on your tube-amp's output tubes with these above. It is, in most cases, perfectly normal.
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