Early Electronic Television
RGD 382-RG CRT (Mazda CRM-121)
This is a Mazda CRM -121 B. There is some question about when this tube was put in the set. Most pre-1945 CRTs were longer than this tube and used electrostatic deflection; however, this type of CRT was available in 1939. The schematic we have uses magnetic deflection, but there is no date on it, so it could have been published after the war.
The RGD brochure mentions the Ediswan 12H as the tube in the 382 sets. It is known that RGD modified many of its TV sets after the war, because the pre-1945 CRTs would have gone weak from sitting unused so long. It is likely that this CRT was added by the factory after the war, along with a replacement time base chassis. Additional evidence to support this theory is that several of the electrolytic capacitors in the set have a Feb. 1946 date stamp on them, suggesting that the set was refurbished after the war.
Thanks to Ian Watson for this information.
Here is a photo of the inside of a 1938 model RGD set, showing an electrostatic tube.