The UY11 is an indirectly heated half wave rectifier designed to operate in AC/DC mains equipment.
The 100 mA heater is designed for series heater chain use and can supply up to 140 mA of output current and is rated to work with a large maximum reservoir capacitor of 50μF as long as the appropriate series resistance is included in the anode circuit to limit the peak current.
This exhibit has lost its vacuum as can be seen by the milky patch where the getter used to be.
Side view with the oxide coated cathode visible through the hole in the anode.
The insulators are ceramic and this is normally found in high voltage rectifiers not those for domestic equipment. At the base of the cathode can be seen the extra insulation that has been placed between the heater and the cathode. The heater/cathode voltage difference could be the full mains voltage.
The wide glass tube envelope is 36 mm in diameter, and excluding the Footless base pins is 91 mm tall.
Reference: Data-sheet. Type UY11 was first introduced in 1939. See also1939 adverts.
