Description
Physical description
Cavity Magnetron Type E 1189
History note
The cavity magnetron was developed from the work of J T Randall and H A Boot at Birmingham University in early 1940. It became the preferred source of very high frequency radio waves in various radars and communication devices, and led to a massive growth in microwave radar technology. Today it is best known as the essential part of the microwave oven. In particular, the cavity magnetron formed the core of centimetric radar with its high definition image on the CRT presentation screen.
At the beginning of September 1940, at a time when Great Britain faced a Nazi invasion, the Tizard Mission, composed of eminent British scientists, arrived in America. The Mission carried the latest British researches on jet engines, the uranium (atomic) bomb, predictors, proximity fuses, rockets, radar, and the cavity magnetron. The magnetron was shown to an impressed American National Defence Research Committee on 28 September 1940.
This technological revelation galvanised the Americans into action. Manufacture quickly followed of both American systems, and copies of British systems. There was close cooperation between British and American scientists at the Radiation Laboratory at the Massachusetts Institute of Technology. The British Telecommunications Research Establishment was also in the forefront of the development of radar and associated systems.
The E 1189 is a very early unstrapped magnetron which was the original design for high-power pulse operation in aircraft . (The first strapped magnetron, ie interconnecting the various segments of the magnetron which diminished mode hopping and increased wavelength definition and CRT resolution , was activated on the 11 September, 1941). Designed by ECS Megaw of GEC and based on the laboratory model of Randall and Boot, it was completed on 25 May 1940, and first operated on 29 June 1940.
The E1189 was the first production-series magnetron and delivered in pulsed operation 12kW on the 9.5 cm wavelength. The last of the first batch of twelve E1189 magnetrons, manufactured by GEC at Wembley, accompanied the Tizard Mission across the Atlantic.
This particular magnetron, produced after the initial run of a dozen, is one of the first production series.
Eventually, the growing electronics industries of the United Kingdom, the United States, and Canada manufactured well over a million magnetrons before the end of the Second World War. The mass-production of the cavity magnetron and the rapid development of viable A I, ASV, EW, GL, and LORAN centimetric radar and navigational systems profoundly influenced the Allied prosecution of, and ultimate victory in, the Second World War.