The N16 is a dry battery audio output pentode. It came in a plain brown cardboard box with the Marconi label in black on one side and basic identification on the top flap. The price is given as 11/6 with purchase tax extra. Eleven shillings and sixpence in the 1950s was a significant cost to the average household. But it is significant that the brown box signifies a utilitarian product or a war time or post war austerity product, a far cry from the elaborately printed boxes of the 1920s and 1930s.
This M-OV valve carries the Marconi brand label.
The top of the valve assembly. The three grids are clearly visible as are the filament tensioning springs at the top above the mica. The mica also defines the position of the two filament strands as they pass through the grids.
Seen from the other side the welded U wire holding the filament springs is clear. Note how the filament support employs a main strut, a U strut, two pieces of ribbon bent to shape and finally the spring wires themselves.
The pinch and base of the main valve. The filament support again is welded to another wire, this time the one passing into the pinch.
The dome distorts the view but the position of the grids and the support structures can be identified.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 71 mm tall.
References: Data-sheet & 3002. Type N16 was first introduced in 1946.