Sensibly equivalent¶ to:
The DH63 is a double diode triode and was designed for receiver audio use.
The diodes would be for signal and AGC rectification and the triode would act as AGC amplifier or first audio amplifier.
A closer look at the electrode construction. The bright box is in fact the pair of diode anodes, one either side of the cathode tube. The common cathode then passes through the blackened triode anode. The grid supports are at the top and the wire leading to the top cap is easily seen.
The classic envelope is 38 mm in diameter and, excluding the IO base pins, is 98 mm tall.
References: Datasheet, 1040 & 1043. Type DH63 was first introduced in 1937.
Absolute Maximum Operating Conditions¶
Updated February 26, 2013.