The CV2106 is a sub-miniature audio output pentode based on the commercial Mullard DL66. The CV specification shows that it was specified for use by the GPO.
The red band indicates the anode connection. Through the bright anode the grids can be seen.
The single strand filament wire is supported at the top by a tensioning spring.
The flattened oval shape of the sub-miniature envelope.
The thin glass tube envelope is 6 mm x 8 mm, and excluding the base wires is 34 mm tall.
References: Data-sheet. Type CV2106 was first introduced in 1950. See also1950 adverts.
