Radios are a popular media today, predominantly used for receiving commercial broadcasts worldwide, however, many of us now rely a great deal on other forms of communication in our everyday lives, including worldwide fibre-optic and cable lines for speech, television and data (internet) use. However, for most of the 20th century, such links did not exist between most parts of the world, if at all, and even today, many communication links need to be made where there are no well-established infrastructure to make the connections required. Long distance communication by radio began early in the 20th century with the advent of the first transatlantic radio communication. Once the abilities of shortwaves to propagate long distances was established in the 1920’s, high-performance shortwave receiver development commenced in the early-1930’s for both domestic and commercial use, using all of the newly-developed receiver technologies as they became available. So was born the concept of the ‘communications receiver’, designed to provide a very high level of performance. These sets have greater sensitivity and selectivity abilities than domestic receivers and cover many more frequencies. Much commercial communications traffic was made using ‘CW’ (continuous wave), using Morse code and teletype techniques, and this requires the receiver to have a ‘beat frequency oscillator’ (BFO) included in its design – the presence of which is often used as the test to whether a receiver is classed as a communications receiver or not. Communications receivers were, and still are, used in a variety of applications, including diplomatic, military, commercial, news and radio amateur (‘ham’) applications. Many of these sets were manufactured to very high standards and were very expensive in their day.
The SPARC museum has a large number of communications receivers on display from most of the major manufacturers, many of which are now out of business, including Marconi, Hammarlund, Eddystone, National, Hallicrafters, RCA and Collins. Some of these sets have been restored by volunteers, others are in their ‘as donated’ condition. The collection also includes some examples of locally-made communications receivers such as the ‘VRL’, made by the Vancouver Radio Laboratories (later Chisholm Industries Ltd.).