The ELL80 is a double output pentode. It was designed as a push pull audio output stage in a single envelope or as a three Watt single ended stereo amplifier. The two valves have a metal screen between them and a common cathode and suppressor grid. The total dissipation is given as 2 x 6 W. and the output is given as 3 W per channel in stereo use. The cathode resistor is given as 160 Ohms.
Like so many other valves the BVA encouraged several manufacturers to make versions of each others valves to ensure set makers would be assured that damage to one production facility would not end supply.
The anode of one pentode with the grids within. The two valves are aligned in the envelope and one can see through both.
The anodes side by side. The cooling fins are on the screen grids. The copper rods are the control grids.
The complex arrangement of connections between the valves and the base pins.
The copper control grid supports can be seen with the flattened cathode tube between. The heat sinks are connected to both supports of both screen grids. No g3 can be seen so possible these are a pair of beam tetrodes. A look into the anode space does confirm this.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 71 mm tall.
References: Datasheet & 1040 Type ELL80 was first introduced in 1959.