The Type 30 is a general purpose amplifier triode. It is directly heated for use with battery supplies. The 2.0 Volt filament was for use with a lead-acid accumulator.
The RCA logo on the base cap.
The bright anode with the grid extending below. the central vertical support holds the filament tensioning spring.
The classic envelope is 38 mm in diameter and, excluding the UX4 base pins, is 90 mm tall.
Reference: Data-sheet. Type 30 was first introduced in 1930. See also1930 adverts.
