The PCC189 is a low impedance high gain double triode. The technical specification specifically states that it is built with frame grids. The valves are variable μ types for use at RF as AGC controlled devices. The low voltage high current suggests a low noise design, probably as the front end stages in a television tuner. The low anode voltage suggests both stages used as a cascode (series connected) amplifier.
Mullard describe the PCC189 as: a VHF variable-mu frame-grid cascode double triode.
The Yellow paint dates this no earlier than 1969 and the Golden anniversary of the founding of the company.
The twin triodes. Not the the use of a double mica, this would improve vibration resistance.
The working face of the anode is at the end of the depression, the rest is heatsink.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins it measures 50 mm tall.
References: Data-sheet & 1040. Type PCC189 was first introduced in 1960. See also1960 adverts.
