The DH101 is a double diode triode from the late 1940s. It was designed for use in superhet broadcast receivers employing a 100 mA series heater chain and was thus used in both AC and DC sets.
In the set the function would be AM detector AGC rectifier and first audio amplifier. The DH81 is very similar and made for use in all AC mains sets.
The triode is at the top of the envelope and below the central mica the common cathode tube has two small collars around it and these are unscreened diode anodes.
The Marconi paper brand label.
Thanks to Mark Mallison for sending the images.
The wide glass tube envelope is 32 mm in diameter and, excluding the B8B base pins, is 56 mm tall.
Absolute Maximum Operating Conditions¶
Updated December23, 2019.