The PL82 would normally be found in audio stages of television receivers. A pair used 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.
The three wire grids of the pentode can just be seen. The anode is stitched together.
The control grid has copper supports and these are topped with heat sink fins to prevent overheating of the grid.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 69 mm tall.
References: Datasheet & 1040. Type PL82 was first introduced in 1951.