I just got my 4-1k tube. It turned out to be a Sylvania brand.
I know Sylvania sold transmitting tubes.
But did Sylvania make them or buy them from another vender?

This one I got from ebay:
has a code date of 8806.

The history on it: was pulled from an AM
broadcast station in 1993, from the AM modulator.

And does anybody know the cold resistance or the filament?
I haven't seen any inrush current limiting circuits for the 4-1k.

73

n8zu