Although the PL82 would normally be found in frame output stage of a television receiver, a pair used as an audio amplifier in push pull class AB1 would deliver 9 Watts at 4 % distortion.
The peak to peak grid signal voltage would be 26 Volts and the shared anode load would be 4,000 Ohms.
Like so many valves in the latter days of production this Mazda valve is an import. The stigma attached to non British manufacture remains on this exhibit as it is labeled with the pejorative term 'Foreign'.
This is a true pentode with three wire grids. Only the inner two are visible in this image.
The thin glass tube envelope is 22 mm in diameter and, excluding the B9A base pins, is 69 mm tall.
References: Datasheet & 1040. Type PL82 was first introduced in 1951.