AUDIO VALVES: ML6 CV1105 VR105 VT105 TRIODE VALVE VARIOUS MANUFACTURERS
The ML6 ceramic based triode was simply a version of the ML4 adapted for operation in sets powered by vehicle batteries.
ML6s were widely used as RF oscillators in medium-sizes military transmitters, in particular the RAF T1154 where they acted as driver valve for the PT15 output valves.
Today, they are prized for their superlative performance in audio applications - simply superb.