Louden valves were marketet by Fellows Magneto Co. Ltd. in 1924 and 1925. Some Louden designations used were FE1 and FE2 for bright emitters; FER1, FER2 and 0.06 designated dull emitters having thoriated filaments.
Bibliographie
Saga of the Vacuum Tube, Tyne page 392
British Radio Valves - The Classic Years: 1926-1946 p. 246 & Supplement, p. 48
FER2_4Volt: Fin Stewart
Fin Stewart
Just Qvigstad
FER2_4Volt: Banneitz, TB der drahtl. Teleph. 1927
Anonyme 15 Collectionneur
