The DE6 was introduced in 1924 and this exhibit carries the BBC type one stamp etched into the envelope. The type one BBC stamp was in use from November 1922 until September 1924. Thus this exhibit is one of the first DE6 valves to be produced. Later versions of the DE6 had bakelite base caps rather than the metal shell seen on this exhibit.
The filament is thoriated tungsten and the DE6 was designed an an audio output valve.
The M-OV initials on the moulded base and the cylindrical anode mounted horizontally within.
In this view the filament can be seen as a broken single strand. The helical grid is supported at the bottom of the loops only.
The balloon envelope is 45 mm in diameter and, excluding the B4 base pins, is 96 mm tall.
References: 4051 & 1003 Type DE6 was first introduced in 1924.