Sensibly equivalent¶ to:
The DF66 is a sub miniature audio amplifier pentode. The design was specifically for hearing aid use where the HT would be supplied by a 22.5 volt battery.
The red paint spot identifies the position pf wire 1.
The anode is 8 mm long and the grids can be seen through the hole in the side of the rounded anode.
The thin glass tube envelope is 8 x 5.5 mm in, and excluding the base wires is 25 mm tall.
Reference: Datasheet. Type DF66 was first introduced in 1951.
Absolute Maximum Operating Conditions¶
Updated February 13, 2013. shape:thin.glass.tube construction:all.glass type:pentode age:1950.1960 base: pin:1.a pin:2.g2 pin:3.f+ pin:4.g1 pin:5.f-.g3