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Summary
DescriptionToroidal telephone loading coil.jpg
English: A loading coil for a 1922 AT&T long distance telephone trunkline between New York and Chicago. It consists of a toroidal iron core with two 0.175 H windings. Each twisted pair in the telephone trunkline is attached to a loading coil. The coils are contained in steel tanks on the telephone pole, immersed in oil. The line required a loading coil every 6000 ft.
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