The 6CW4 Nuvistor from RCA is a triode for use at VHF and built into a small metal case. The base is ceramic sealed to the metal case and five fine pins, on a 12 pin grid, form the connections and the electrode supports internally.
The Nuvistor is built as a series of co-axial electrodes but they are all very small, and small inter electrode capacitances result. Thus the high frequency of operation. Unlike the transistors of the time the Nuvistor had the overload and intermodulation characteristics of the valve, superior to the transistor.
This exhibit is shown seated in its socket. For the un-socketed version see 6CW4.
The side lugs on the valve enter the slots in the base. Here the slots are on either side of the base.
The underside of the valve base.
This image shows a different type of Nuvistor valve base. The fingers will provide better screening in an RF environment.
The thin metal tube envelope is 9 mm in diameter and, excluding the fine base pins, is 15 mm tall.
Reference: Datasheet. Type 6CW4 was first introduced in 1960.