The EL36 is a purpose designed line output valve for television receivers. Most TV receivers were AC/DC designs that did not employ mains transformers and had the heaters in series across the mains. In the UK, with 240 V mains, a 300 mA heater chain was common. The PL36 was the normal valve for heater chain use.
This exhibit is of modern design with a pressed glass foot and not an old style pinch. The 1940's EL36 audio output valve lacks the top cap of the EL36 television valve with the same Type designation.
The side of the box anode. The control grid cooling fins can be seen at the top of the envelope. The structure supported at the top of the anode struts is the getter holder.
The grid support wires are copper for better heat conduction. The grid cooling fins are spot welded to the control grid supports
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 95 mm tall.
References: Data-sheet, 3002, 1040 & 1043. Type EL36 was first introduced in 1956.