'R' VALVE, BBC MARKING AND BASE, 1923

The 'R' Valve was developed from the French hard vacuum valve of WW1 and was made in the UK from 1916 by the Marconi Osram Valve Company. Its use in new equipment declined in 1925 with the introduction of the lower power dull emitter valves.

The first ever broadcast from Savoy Hill in 1923 used these valves in the audio amplifier. This was the first UK Hard Vacuum valve to go into production, historically so important that a company in Europe started making copies for enthusiasts who wished to make early wireless sets work.

A0770