The SP2 is a directly heated battery pentode from 1934. It was designed for broadcast radio reception.We also have the older balloon style SP2 with the screw top cap.The classic envelope is 43 mm in diameter and, excluding the B7 base pins, is 115 mm tall.References: Data-sheet & 4024. Type SP2 was first introduced in 1934. See also 1934 adverts. |