The HF93 is a variable μ pentode for use at HF within AC/DC receivers. Most probably as RF or IF amplifiers. This particular Mullard valve was made by the parent company Philips in Holland.
Looking along the grid axis, the suppressor grid is the easiest to see.
The plain rear of the cylindrical anode.
The thin glass tube envelope is 17 mm in diameter and excluding the B7G base pins, is 47 mm long.
