Marconi radio equipment with headphones. This is a Marconi Marine Receiver No. 4b. It has two valves and a tuner covering all wavelengths between 300

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Marconi radio equipment with headphones. This is a Marconi Marine Receiver No. 4b. It has two valves and a tuner covering all wavelengths between 300 and 28,000 metres. It can be fitted with a crystal detector in an emergency. Thermionic valves (also called vaccum tubes) and crystal detectors, were two types of radio technology. Marconi patented his radio equipment in 1896. His initial aim had been to allow communication with those at sea. Photographed for The March of Commerce (1927), volume 4 of The Pageant of America: A Pictorial History of the United States. This was a 15-volume series that commemorated 150 years since the founding of the USA in 1776.

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Size: 2561px × 3407px
Photo credit: © HUMANITIES & SOCIAL SCIENCES LIBRARY/NEW YORK PUBLIC LIBRARY/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

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