Research Enterprises Ltd., also known as REL, was established in Toronto, Canada, as a Crown corporation, branch of the National Research Council of Canada (NRC). Its original role was to build optical instruments, sextants, binoculars and gun-sights for England. From the Tizard Mission in 1940 it was involved in volume productions of British RDF (radar) sets and in development and delivery of microwave sets as well as of vacuum tubes.

REL played an important role until America entered the direct war. In fact, it allowed Americans to supply strategic materials to the British through Canadian industries, without exposing themselves directly.

In 1939 Canadian NRC was involved as focal point in the development of radar equipment. Canada could benefit from the specific knowledge of the British pioneers together with the wide components and materials availability of the near U.S. market. Even before England entered the war with Germany, the importance of RDF equipment - Radio Direction Finding or radar - was understood for an effective defense of the island from air and / or naval attacks. England, under pressure from the growing demands of the military at the beginning of the war, decided to involve REL in the volume production of RDF systems, starting from cathode ray tubes, which could easily be built due to the very modern optical equipment there available.REL started producing CRTs in a 500 people plant, under the management of GE Co. In October 1940, the technicians of the Tizard Mission, that is Cockroft, Wallace and Bowen, went to Ottawa to transfer to NRC and REL information on many of the RDF sets defined and of which the Mission had just agreed preliminary milestones with the Americans. E1189 No. 12, the first eight-cavity magnetron that Mission Tizard had brought to America, was also left in Canada and is today on display in the National Research Council museum in Ottawa.

From 1941 to 1946 REL produced more than 10.000 radar sets. Among them about 10.000 ASVs, mostly for America, about 630 GL IIIC 10 cm trailers and the sets for the Panama Channel CHL surveillance system. About 7.500 people were employed at the peak, external subcontractors being used whenever advantageous. At the beginning many of the tubes were copies of those developed in England. This is especially true for volume production of equipment previously developed by the British, ASV and CHL. Other tubes for the still developmental 10 cm sets were redesigned with the help of the NRC and of the same MIT Radiation Lab. Only later during the war REL registered a few tubes that it had developed. REL itself did not build radar specific tubes other than CRTs; rather it subcontracted their production to other Canadian manufacturers, Rogers, GE Co., Canadian Westinghouse and Northern Electric. REL just appeared as prime contractor for many tubes, magnetrons, klystrons, CRTs, spark-gaps or trigatrons, TR and ATR cells, badged with the prefix REL followed by a combination of one or two digits and sometimes by a literal suffix. When, starting from 1944, the American industry took a leading role in the production of equipment, especially those in the X band, REL continued to delivery equipment for allied countries such as Russia or for being deployed on minor theaters