The DS310 is an acorn triode for operation at UHF from battery supplies.
This exhibit was made for the German state and approved by testing site BA 4721.
The electrodes are small and the leads short to enable operation in the UHF region around 500 Mhz and above.
The multi metal pins are given extra strength by the ring of glass. Inside the ends are flattened and the leads spot welded to them. The insulated heater wire is wound as a double helix and the cathode connection is by flat tape.
The internal base disc looks to be ceramic.
The packing slip found in the box.
The thin glass tube envelope is 15 mm in diameter and, including the base pins, is 41 mm tall.
Reference: Data-sheet. Type DS310 was first introduced in 1938. See also1938 adverts.
