The EBF80 is a variable μ amplifier pentode and a pair of signal diodes in the one envelope. Probably this was designed, as was the later EBF89, as final IF amplifier and AM detector. The other diode would provide AGC rectification.
The coating inside the glass in line with the holes in the anode looks to be present to prevent electron bombardment from releasing gas from the glass.
Apart from the lower screens and the thickness of the support micas, little can be seen.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 59 mm tall.
References: Data-sheet, 3002 & 1040. Type EBF80 was first introduced in 1950. See also1950 adverts.
