The W17 is a miniature variable μ screened pentode for dry battery operation. It was designed for radio reception and operates at RF and IF into the low HF bands.
The Osram brand label.
The three grid supports with a glimpse of the wire grids through the notch in the anode.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 46 mm tall.
References: Data-sheet & 3002. Type W17 was first introduced in 1947. See also1947 adverts.