Tung Sol / Chatham 6394A vacuum tube - perfect condition - popular new old stock - original box - 6336A with 26.5 volt filament

Very pretty, no?
Tung Sol 6394A tube in perfect condition and in original box. Big sturdy graphite plates.

What's a 6394A? It's essentially a 6336A with a 26.5 volt filament.
And you're thinking why is popular that something you'd want, right?

I've built quite a few circuits with 6336A's and they draw 5 amps of filament current. Not such a big deal if you're only dealing with one tube but suppose you have 4. And suppose you want to make a separate power supply or need the filament transformer to be a good distance from the tubes?

If you take relatively big wire, say #14, it has a resistance of 8 milliohms per meter. 20 amperes will drop .32 volts (remember you're going out and back) and that just for 1 meter of cable and its for #14 wire which doesn't fit on most tube sockets very neatly. And that doesn't include any drops across connectors

6394A's filament pulls only 1.3 amperes. And it's 26.5. So you could even series string them.

In any case what we have here is a beautiful tube in search of a project.