Museum of Communication at Burntisland

Domestic Radio

Invention History

This section traces the development of "wireless" in the home from the earliest days dating back 100 years. In the last quarter of the 19th century many scientists were trying to transmit messages over distances without wires. Their purpose was to explore the possibility of using electromagnetic waves in order to communicate between two fixed points. However, the history of "wireless" communication eventually became the history of broadcasting.

Radio has no single inventor, but grew out of several international developments. Following from the work of Heinrich Hertz, it became obvious that in order to receive radio signals, sensitive equipment was needed. Experiments by Edouard Branly and Oliver Lodge led to the invention of the Coherer Wireless Receiver, in which a glass tube containing iron filings between contacts, closed a relay and started a Morse printer inking device on a clockwork recorder. By the turn of the century, Marconi was working on the Morse Magnetic Detector, which produced clearer and more reliable signals than the Coherer. The first valve made its appearance in 1904 and soon it was possible to transmit speech.

1920s

The Crystal Detector first brought radio into our homes. The popular crystal was Galena, a sulphide of lead. You had to search with a spring of fine wire - the Cat's Whisker - for the crystal's sensitive spot. All the energy in the headphones came directly from the aerial (which was as long as possible) and a good connection to earth. As Crystal Sets were powered solely by transmitted radio waves, they required no batteries, but range and selectivity were limited. The BTH Twin Crystal Receiver (see left) dates from November 1922. The case lid carries the BBC stamp and Post Office registration number - all pre-1925 factory built equipment was thus stamped and a Royalty paid to the BBC. At a time when the average weekly wage was £1. 10s (£1.50), this set cost £1.15s, plus a Royalty of 7s.6d = £2. 2. 6d (£2.13p) The Miniature Wireless Marvel typified the craze for miniaturisation in the early 1920's - but this tiny crystal set in a matchbox still needed a very long aerial and earphones! Wireless sets and components were expensive, so many amateur enthusiasts purchased a "Constructors Licence" for 15s. 0d and proceeded to build their own. The amateur built Receiver (1923) has five valves (the fifth is internal) and interchangeable tuning coils (see below). These components alone probably cost about a month's wages but the factory built mahogany "Smoker's Cabinet" would have been five or six times that amount.

Mary J. MacDonald, 6 Oct 2005

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