The tube was one offered to me for the cost of postage, I don't
know its history. It showed no signs of life and high hipot
leakage so I opened it up.
I think the photos were taken with my first digital camera -
Olympus C1400XL. Not so many pixels, but a large diameter lens and
good optics.
I've seen similar looking damage in smaller tubes attributed to
cathode overheating when airflow was inadequate. Other than
keeping it cool, I'd suggest you run the lowest plate supply you
can for the gain/power you need, avoid hot switching relays and
look after the loading.
Steve
Nice clear photos. What would have made that happen? And how to best
avoid it from happening to... lets say, my amp?
Gary
KA1J
I opened and photographed a dead one a while ago. The pictures are
here:
http://gs35b.com/gs35b/bang.html
Would the drift happen if a tiny bit of cathode material
evaporated and migrated to the grid?
Steve
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