The specimen shown is an ML6C (with ceramic base) of WWII vintage. The ML6 was simply a version of the ML4 adapted for operation in sets powered by vehicle batteries. The presentation of the Type designation is typical of M-OV.
ML6s were widely used as RF oscillators in medium-sizes military transmitters.
The face view of the triode. On the right can just be seen the AM for AirMinistry and the crown above. Below the AM is the RAF Type code of VT105.
Side view with the crown to the left of the lower mica.
The classic envelope is 45 mm in diameter and, excluding the B5 base pins, is 98 mm tall.
