Country:USA (United States of America) Manufacturer: Common type USA tube/semicond. Type: Pentagrid converter (Heptode) Frequency converter Control (mu) Identical to 2A7 = Ut-2A7 = ER2A7 = CV787 = PH2A7 = Ut2A7 = NU-2A7 Similar valves Other shape (e.g. bulb type): 2A7S ; G-2A7-S Other class quality (otherwise equal): NU-2A7S Heater different: 6A7 First series 1933 Radios von gestern, 2. Auflage page 231 (Base for 2A7 and 6D7)started >200 models First information Apr.1933: 70 Years of Radiotubes and V. Mar.1933 : The AWA Journal Vol. 7, 1992 Evolutions 6A8 6A8G