Tyne: "Double-grid tubes came on the French market in 1924. At first they had tungsten filaments. By 1925 they were superseded by the dull-emitter version, space-charge rather than shield-grid tubes, and were first used in receivers at low anode voltage. Later they were used as frequency changers in superheterodynes. Examples of these are Métal's DG and RM, La Readiotechniaue's Micro-Bigril R43, and Grammont's Bigrille-Ampli and Bigrille BF." [EE]
Micro-Bigril_R43: W.H.
Wolfgang Holtmann
Micro-Bigril_R43: W.H.
Wolfgang Holtmann
Micro-Bigril_R43: Banneitz, TB der drahtl. Teleph. 1927
Anonyme 15 Collectionneur
