The ECF82 is a high slope triode pentode designed for television use as a frequency changer or mixer. It was also found to be effective as an audio phase splitter and used by Radford.
The envelope has the older logo and white lettering including the words 'Foreign Made'.
Face view of the triode with the single side stitching of the anode on the left.
Looking along the grid axis of the beam tetrode. The hole in the end of the beam plates reveals the screen grid end support and the width of the screen grid can just be made out.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 48 mm tall.
References: Data-sheet & 1040 Type ECF82 was first introduced in 1953. See also1953 adverts.