The DL64 is an audio output pentode designed for use in hearing aids where the anode voltage available is 15 Volts. The DL64 is designed for use in Class A and generates up to 0.95 mW of output.
The red paint spot on the envelope at the base indicates the anode pin.
Through the side wall in the anode the wire grids can be seen. The filament is a single strand of oxide coated wire.
The filament tension spring and filament can be seen on the right of the image.
Thanks to Ian Summers for donating this valve.
The thin glass tube envelope is 6 x 8 mm, and excluding the base pins is 34 mm tall.
Reference: Data-sheet. Type DL64 was first introduced in 1954. See also1954 adverts.
