File:First US Navy radiotelephone.jpg
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![File:First US Navy radiotelephone.jpg](https://upload.wikimedia.org/wikipedia/commons/thumb/3/39/First_US_Navy_radiotelephone.jpg/384px-First_US_Navy_radiotelephone.jpg?20130919062649)
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[edit]DescriptionFirst US Navy radiotelephone.jpg |
English: First experimental radiotelephone system on a US Navy ship, built by American engineer Lee De Forest in 1907. One of the earliest AM (voice) radio systems, 26 units were installed on the ships of the "Great White Fleet" and tested on their well-publicized around-the-world cruise in 1908. This picture is of the unit installed on the bridge of the flagship, USS Connecticut. It consisted of a 40 kHz transmitter (left) using a variation of the Poulsen arc oscillator, and a receiver (right) using De Forest's Audion vacuum tube as a detector. The set had a limited range of about 5 miles. The transmitter uses an oscillator consisting of a 220V arc between copper and carbon electrodes in the flame of a small alcohol lamp (visible on R side of unit) attached to a resonant circuit consisting of a coil of wire and capacitor in series. The negative resistance of the arc excites resonant oscillations in the tuned circuit. The antenna is attached to an output coil inductively coupled to the first coil. The carbon microphone visible on the front of the unit is connected directly in the ground wire of the transmitter. However the Navy evaluated these devices as a failure, and they were scrapped after the cruise. Information from . Herbert T. Wade, "Wireless Telephony for the Navy", Telephony magazine, May 1908, p. 365-367. Caption of picture: THE FIRST SET OF WIRELESS TELEPHONE INSTRUMENTS FOR THE UNITED STATES NAVY. INSTALLED ON THE FLAGSHIP USS CONNECTICUT. Alterations to image: Removed aliasing artifacts (background grid of stripes) introduced by scanning the halftone photo using the FFT filter in GIMP. |
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Source | Downloaded 6 September 2013 from Charles G. Ashley, Charles B. Hayward (1912) Wireless Telegraphy and Wireless Telephony, American School of Correspondence, p. 87 on Google Books |
Author | Lee De Forest |
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[edit]Public domainPublic domainfalsefalse |
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This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
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This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.
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English: Carbon microphone in output line to antenna amplitude modulates output by varying current to antenna
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English: Transmitter
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English: Oscillator for transmitter consists of Poulsen arc between carbon and copper electrodes in flame of alcohol lamp
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English: "Transmit/receive" switch connects the antenna to either transmitter or receiver
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English: Lightning antenna disconnect switch
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English: Rheostat to adjust current to transmitter arc
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current | 06:26, 19 September 2013 | ![]() | 1,356 × 2,114 (329 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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