The DK92 is a miniature heptode frequency changer for use in dry battery powered radio receivers. Domestic long and medium wave receivers would have this as the mixer to produce a 455 kHz IF from the incoming signal. It can be used with a separate oscillator, but was probably designed as a self oscillating mixer, in the manner of other pentagrid converters.
The reduced height anode cylinder allows the grids to be seen.
At this angle the grid details are easier to see. The grid wires are fixed to the supports by the standard notch and peen mechanism.
Above the top mica is the top filament connection and the associated tensioning spring.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 47 mm tall.
References: Data-sheet & 1040. Type DK92 was first introduced in 1951.