The PL802 is a purpose designed video output pentode for driving a cathode ray tube with the wide bandwidth signal needed for colour TV picture information.
The anode is shaped as a pair of flat plates either side of the grids with thin straps joining them together at top and bottom. the maximum anode dissipation is six Watts. The figures given are typical operating conditions but the maximum anode voltage is 300 Volts long term average with 400 Volts peak.
The detail of the electrodes can be seen. The suppressor grid is a metal frame and the screen grid can be seen as the visible wire grid. The high mutual conductance figure of 40.0 mA/V is achieved with a very fine control grid almost touching the cathode. It cannot be clearly seen from the picture.
Here we have a UK made version of the PL802.
The beam plates and screen grid.
The outside of the working part of the anode.
The thin glass envelope is 20 mm in diameter and, excluding the B9A base pins, is 57 mm tall.
Reference: Data-sheet. Type PL802 was first introduced in 1966.