BBC marks

BBC/GPO

In the early days of broadcasting, as sets became available to the general public, there was concern that these regenerative receivers could also act as transmitters if the reaction control was advanced too far by an unskilled user, thereby causing quite severe interference to other nearby receivers. To reduce this possibility, on November 1st., 1922, regulations were introduced requiring all valves and receivers sold in the U.K. to be type approved by the G.P.O. and to bear a 'BBC' stamp or mark. Royalties were charged on valves and sets were 'sealed' and could not be modified. On October 1st., 1923, valve royalties were abolished. The mark shown above was used until September 1924 when the marks shown below were introduced.

BBC

From 1924 onward, only BBC associated companies were required to use the marks and even this requirement was removed on January 1st., 1925. The marks had some cachet and continued to be used by some manufacturers until as late as 1927. The marks can usefully indicate an approximate date of manufacture for valves bearing them.

BVA

The British Valve Association was formed in 1926 from the Valve Association. Companies involved included A.C. Cossor, Edison Swan, GEC, Marconiphone, Mullard and Standard. Valves bearing a BVA marking cannot have been manufactured before 1926.