File:Emmetteur.jpeg
Emmetteur.jpeg (450 × 302 pixels, file size: 59 KB, MIME type: image/jpeg)
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Summary
editDescriptionEmmetteur.jpeg |
Français : Vue intérieure de la salle des arcs de l'émetteur de Lafayette.
Premier émetteur radio à arc de Poulsen dans une station française équippée par la marine américaine à Croix d'Hins, Bordeaux, France. Les deux émetteurs de 1 mégawatt représentés ici, construits par la Federal Telegraph Co. en 1919, qui pouvaient émettre en continu à une puissance de 500 kW et pendant une courte période à une puissance de 1 MW, étaient l'un des plus grands émetteurs à arc jamais construits. Le convertisseur à arc Poulsen, inventé en 1903 par Valdemar Poulsen, était l'un des premiers émetteurs radio à ondes continues et l'un des premiers à pouvoir transmettre de la MA (voix). Il s'agit d'une technologie éphémère qui a été utilisée de 1903 jusqu'au milieu des années 1920, date à laquelle elle a été remplacée par des émetteurs à tube à vide beaucoup moins chers et moins encombrants. L'appareil se composait de deux électrodes à arc horizontal, d'une anode en cuivre refroidie à l'eau et d'une cathode en carbone, placées dans une chambre à hydrogène entre les pôles d'un puissant électro-aimant. Un circuit accordé composé d'une bobine et d'un condensateur était connecté aux électrodes. Lorsqu'une tension continue était appliquée pour créer un arc, des oscillations de radiofréquence étaient générées et appliquées à l'antenne. L'émetteur fonctionnait dans la gamme des très basses fréquences (VLF) et avait une portée de plusieurs milliers de kilomètres. Il avait un rendement d'environ 46 % et pouvait fournir un courant d'antenne de 750 A.English: Early Poulsen arc radio transmitter at a US Navy station at Croix d'Hins, Bordeaux, France. The two 1 megawatt transmitters shown here, built by the Federal Telegraph Co. in 1919, which could broadcast continuously at a power of 500 kW and for a short time at a power of 1 MW, were one of the largest arc transmitters ever built. The Poulsen arc converter, invented in 1903 by Valdemar Poulsen was one of the earliest continuous wave radio transmitters and one of the first that could transmit AM (voice). It was a short-lived technology which was used from 1903 until the mid-1920s when it was replaced by much cheaper and less bulky vacuum tube transmitters. The device consisted of two horizontal arc electrodes, a water-cooled copper anode and a carbon cathode in a chamber of hydrogen gas between the poles of a powerful electromagnet. A tuned circuit consisting of a coil and capacitor was connected to the electrodes. When a DC voltage was applied to create an arc, radio frequency oscillations were generated, which were applied to the antenna. The transmitter operated in the very low frequency (VLF) range and had a range of thousands of miles. It was around 46% efficient and could supply an antenna current of 750 A. |
Date |
circa 1925 date QS:P, 1925-00-00T00:00:00Z/9,P1480,Q5727902 |
Source | postcard |
Author | UnknownUnknown |
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current | 09:44, 16 September 2008 | 450 × 302 (59 KB) | Toto3371 (talk | contribs) | {{Information |Description=Vue intérieure de la salle des arcs. |Source=Carte postale |Date=vers 1925 |Author=Labeyrie |Permission= |other_versions= }} |
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