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Before World War I, interest in radio was restricted to professionals in the industry and a small number of private individuals keen on experimentation. The following are wireless themed advertisements published in the first half of 1914. Terms are not yet fully standardized hence, for example, a "Receiver" was a complete wireless set and "Radio or Wireless Receivers" or "Headgear Phones", are headphones. Valves are as rare as hen's teeth. In my search for early adverts I came across an article (dated October 1913) for constructing ones own X-Ray machine including pictures of (I assume) the fingers of the author's son. A little blurred perhaps due to the period of exposure required. He quotes from 1 to 30 minutes... The author also suggests using his home-made high tension generator for wireless telegraphy.. I don't seem to have that article, if indeed he ever got round to testing his ideas before war broke out? Radio was switching from spark transmission using morse code to voice transmission at low powers using valves. During World War I, transmitter valves got bigger and spark transmission began to be superseded until it was eventually only used as a last ditch method of sending distress calls from ships. On the reception front, crystals were still used to detect transmissions and very shortly valves would be used for audio amplification. |
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