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Description
Original Perham exhibit label reads: This 30 kilowatt radio arc transmitter was used in the Marsh Station in Palo Alto. The station, which is located off Embarcadero Road, was built in 1921 and broadcast between 300-1800 meters. The station began to convert from arc transmitters to tubes in the late 1920s. Arc radio transmitters are based upon the well-known method of obtaining undamped radio-frequency oscillations by means of an electric arc. The arc is enclosed in a chamber with an atmosphere containing hydrogen, and the electrodes are placed between the poles of a powerful electromagnet, which produces a strong transverse magnetic field tending to blow the arc out. Carbon or graphite is used for the negative electrode, while the positive is made of copper and water-cooled. The arc converts the energy supplied by the direct current generator into radio-frequency energy with undamped current in the antenna circuit. All parts of the arc converter are stationary except the carbon electrode, which is rotated very slowly. All of the arcs rated at 5 to 100 KW are alike in that they consist of a vertical magnetic circuit with two field coils, one below and one above the arc chamber. The 30 (60, 100 KW) field windings consist of a number of pancake coils wound with copper strip with micanite insulation between turns.
Type
image
Identifier
9BF1B232-4942-4F29-8332-519022867313 2003-1-214
Subject
Federal Telegraph Company Arc converter Telegraph industry Telegraph, Wireless (LCSH) Poulsen Arc Transmitter Radio stations (LCSH) Poulsen, Valdemar Fuller, Leonard Franklin
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