I have a Western Electric "16A" miniature 9 pin tube. It has no getter, and is short like a 6AL5. Inside there is nothing but a long black coiled filament - so it looks like some kind of ballast. The filament is tapped by 2 supports which are tied to pins, so it has 4 pins electrically connected to the filament. Internet searches are plugged up with large "16A horn" speakers, even if I search for the tube. I have no data on this - it's just idle curiosity.
Eddie

:I have a Western Electric "16A" miniature 9 pin tube. It has no getter, and is short like a 6AL5. Inside there is nothing but a long black coiled filament - so it looks like some kind of ballast. The filament is tapped by 2 supports which are tied to pins, so it has 4 pins electrically connected to the filament. Internet searches are plugged up with large "16A horn" speakers, even if I search for the tube. I have no data on this - it's just idle curiosity.

Eddie:
I worked for AT&T many years ago, as we were changing from tubes to transistors, and there is probably no "civilian" tube to match yours. Western Electric equipment was designed by Bell Telephone Labs, and they no interest in following (copying) anyone else. If they bought something from the outside world, it was inspected at the WE labs in Kearney, NJ, and has a Kearney Specification (KS) number on it. That tube might have been used in a piece of equipment for which there is no real world equivalent.
Lewis
:Eddie