The Marconi BL63 is a low-impedance double triode with one grid taken to the top cap.
The BL63 was supplied by M-OV to the RAF during WWII normally as the VR102. Here we have the branded valve complete with the Air Ministry AM markings and 1DE/279 stores code.
The valve has added paper stickers. This one indicates that it has been approved for service use. Quality control in action.
The Air Ministry seal complete with crown. My late father-in-law, a war time Radar instructor, always referred to AM as Arthur Mitchell.
The classic envelope is 45 mm in diameter and, excluding the IO base pins, is 116 mm tall.
References: Data & 1043. Type BL63 was first introduced in 1939. See also1939 adverts.
