MARCONI RECTIFIER MR1 VALVE, 1919

Marconi MR1 (Marconi Rectifier No1). Similar to the unit that would have been used to power the transmitter for the first broadcast from Savoy Hill in 1922, in which Dame Nelly Melba Sang.
The unit was used to turn the Mains Voltage which was Alternating Current into Direct current for the High Tension supply of the Main Transmitting valves.

A0713