The DAF96 is a dry battery valve and exhibits very low filament consumption. This is one of the last generation of dry battery valves, and dates to the early 1950s when portable radio sets were still based on valves. It was designed for detector and first audio stage use and can be found in the small suitcase portable sets of the period.
The side view shows the oval anode and the small volume occupied by the actual electrode assembly. At the top of the envelope the filament is attached to a coiled spring to provide tension.
Seen in close-up the grids can be seen inside the anode. The suppressor grid can be easily identified as the wide pitch helix just inside the anode. The filament appears as a thin black line running horizontally in the centre of the picture. Even under a magnifying glass the tungsten wire that the oxide coating is fixed to is difficult to see as it is very fine.
Here is another specimen. This is new and in the original pin protector, but a hairline crack can be seen in the glass foot. Consequently the vacuum has been ruined and the getter turned milky.
The filament can clearly be seen running along the centre line. The absence of the getter reveals the filament tension spring on the extreme right of the image.
The single diode is formed from the small bright plate to the right of the pentode section.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 48 mm tall.
References: Data-sheet, 3002 & 1040. Type DAF96 was first introduced in 1953.