Duovac VT-2

In 1932, the Duovac company was awarded a contract to produce type VT-2 tubes for the Signal Corps.  The original VT-2 was produced during WW-1 by Western Electric.  The Duovac version was very different in its construction, particularly the filament.  The Western Electric used an oxide coated filament that glowed a dull red, and the Duovac used pure tungsten, which was extremely bright.  The production version of this tube is shown above.  The tube shown below is unmarked, and is identical except for the bulb shape.  It may be a prototype.