The CV1839 is an HF pentode for use in HF, IF, frequency changer or video output stages of television and other short wave receivers. The commercial version is the Mazda 6F13.
The outer perforated screen. On top is the copper supported control grid with cooling fin above.
The original form of the B8A base with metal skirt and central spigot. Location of the equi-spaced eight pins was by the locating pip on the side of the base that fitted into a guide slot on the valve holder.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 52 mm tall.