Prune wrote:
I can find datasheets for 6JM6 online, but not for 6MJ6. Anyone have any
info on this sweep tube?

Not exactly a formal datasheet, but see the following URL for an article
published in QST in Oct. 1974 that summarizes the then new 6MJ6
characteristics:

http://www.thermionic.org/sw6mj6.jpg

It provides info on input and output C, transconductance, max voltages,
currents, dissipation etc....


-Ray WB6TPU