The 6DR8 from Mullard also carries the Mullard EBF83 type designation. The 6DR8 is an unusual low voltage double diode pentode valve. The 12.6 Volt anode rating, coupled with a standard 6.3 V 0.3 A heater, indicates operation from a vehicle battery and the car radio is the obvious application. This generation of hybrid car radios used germanium power transitors as audio output devices with a conventional valve front end.
The mesh screen obscures the construction but two side holes exist and through them it can be seen that the pentode is the lower section. The slope of the getter ring shows that when fired the filling is directed directly above the holder.
Greater detail of the inner construction.
The base section showing the spot welded connections to the electrodes.