The CV1919 is an RF amplifying pentode for operating in a parallel (fixed voltage) environment. Such a device would be used for radio receivers and VHF television.
The inner screening at the top and Made in England on the glass.
The valve is also marked as a Mazda 6F14. The CV identification for the Government contract looks to be an overprint.
Looking down on the valve the copper control grid supports are surmounted by a sizeable square radiator. The cathode tube has been folded into a flat rectangle. The closing double U folds on the side show the construction.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins and spigot is 53 mm tall.
