The CV1055 is directly equivalent to the EBC33, and this exhibit has both names present on the metallising. The valve is a double diode triode. The design dates from the late 1930s. The literature says the device was designed for use as an AF voltage amplifier for use at the end of an IF chain where the diodes would demodulate the AM signal and rectify an AGC control voltage, and the triode would act as the first audio amplification stage.
The KB/DA identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the D identifies the maker as Mullard Radio Valve Co., Blackburn.
Made in Great Britain.
The commercial Type designation of EBC33 plus the Mullard and BVA logos.
The classic envelope is 30 mm in diameter and excluding the IO base pins and central locating spigot is 87 mm tall.
References: Data-sheet, 1040, 1043 & 3002. Type CV1055 was first introduced in 1938. See also1938 adverts.
