Here we have another 'sleeper' tube which is largely ignored by the audio crowd but very well useable as an output tube. The 6HJ5:
The 6HJ5 is a beam power tube which was intended for use as horizontal deflection amplifier in TV sets. Like many of those it can be triode connected and is useable as 'pseudo triode'.RCA data sheet. The data sheet does not show any plate curves. So I took some in triode mode with a curve tracer:
Makes me want to use this tube in a project. But so many tubes and so little time...
Here we have 6HJ5 made by RCA.
6HJ5 made by Raytheon: