RCA UV-199/3 volt
The UV199 uses a unique small base which never was used for other tube types, except the de Forest DV3a and Western Electric 230D. The UV199 is the first tube intended for use in portable receivers as well as in home receivers using dry batteries. The filament is for 3 volts, 0.06 amperes. After a year of release this was rated to 3.3 volts. These are 1920's brass pin.
