The DV-3 is a triode from De Forest that appeared in about 1925. It features a 3.0 Volt filament for use with dry cells. For dry cell use the filament must be a low consumption type.
The rest of the maker's label.
The left side of the dealer's label.
The rest of the dealer's label. The locating pin for the bayonet pin can be seen in the side of the ceramic base.
The four UV base pins.
Using the microscope and looking through the glass at the base the horizontal electrodes can be seen. The anode is an open cylinder and the grid is a wire helix.
At a different angle the single strand filament comes into view. It sags as it has failed.
A better view of the helical grid.
The wide glass tube envelope is 35 mm in diameter, and excluding the UV base pins is 80 mm tall.
Reference: Bill Condon & 1047. Type DV-3 was first introduced in 1925. See also1925 adverts.
