The CV782 and its commercial twin, the 1R5, are miniature heptode frequency changers. The valve design was for dry battery operation.
The KB/D 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., Mitcham.
The tension spring for the single strand oxide coated filament can be seen at the top.
The two screen grids are strapped together at the top of their supports.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 46 mm tall.
References: Data-sheet, 1040 & 1043. Type CV782 was first introduced in 1947. See also1947 adverts.
