HRO

The National Company dates from 1914. They manufactured mechanical parts, including toys, until 1924 when they began manufacturing the famous Browning-Drake receiver kit. In the same year they used their mechanical expertise to begin manufacturing radio components, including variable capacitors and the classic “Velvet” vernier dials.

James Millen joined National in 1928, as Chief Engineer and General Manager. Millen, a talented mechanical engineer, began in late 1933 to develop a communications receiver which was destined to become the most famous in history, a receiver which remained in production in recognizable form for over 30 years.

The National HRO on display has a varied history. It is painted Air Force blue, has a tag with the government reference number and serial number. During World War Two all non essential radio services (Amateurs etc) were closed down for the duration. The military were so short of radio equipment the government resorted to purchasing suitable equipment from these services and having them reconditioned and put into military service. This is one such receiver. According to National production figures, this T series low serial number receiver was manufactured between March-September 1937. This series changed from a silver dial to a black lacquered dial, push-pull S meter switch, a lighted S meter and rectangular IF transformers. Two different power supplies were available to allow the use of either 2.5 or 6.3 volt glass tubes.

Reversed engineered HRO’s were produced by AWA of Australia, Collier and Beale of New Zealand, the Russian 45PK-1, Japanese R-140M and in Germany. In the Canadian Air Force it was known as the GR9 ground station system.