de Forest single wing spherical audion tube, display only. Good filament.

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Here is a REPLICA de Forest spherical audion tube. It is freshly made in my tube laboratory. This is NOT AN OPERATING TUBE in that it does not have any transconductance. In tube making, sometimes things go wrong. (sometimes it seems that there are too many sometimes'es!) This one was to be a gas filled audion. The tube was being tested and the gas pressure carefully adjusted to the correct point, but in my doting old age I forgot to turn off the gas needle valve when I reached the operating pressure. So, while I was sealing off the tube, the gas pressure was still increasing. By the time I discovered the mistake, it was too late: the tube was sealed off. But the filament is good and the tube is filled to some low pressure, probably several hundred microns, of argon gas. Normally I just throw these duds against the wall in frustration, taking satisfaction in the shattering pop it makes. Someone said I was trashing useful tubes! Some people want display tubes that will light up but have no need for the tube to be operational. So I will try listing this one and see if anyone wants it. This one has a good filament and lights up normally with about 3 volts on the filament. (a 2.5 volt filament transformer works just fine) I don't know how long the filament will last while lit. It depends on how much voltage you apply. At the 3 volts, read more

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