Image: Transmitter tank inductor
Description: An inductor used in the output tank circuit of a shortwave radio transmitter. It is a plug-in unit, so it can be replaced to change the output frequency. The coil has a small adjustable coupling link which is used for "neutralization". A negative feedback signal is applied to it from the plate circuit of the output vacuum tube to cancel positive feedback though the tube's plate-grid interelectrode capacitance, to prevent parasitic oscillations. It shows typical high Q construction: the winding is a single layer with the turns spaced apart to reduce losses due to proximity effect and parasitic capacitance; to reduce dielectric losses it is supported by only a few thin plastic supports. Alterations to image: cropped image out of a larger image of an RF amplifier in a shortwave transmitter.
Title: Transmitter tank inductor
Credit: Retrieved March 12, 2014 from Radio News magazine, Ziff-Davis Publishing Co., Chicago, Vol. 20, No. 11, May 1938, p. 31 American Radio History website
Author: Unknown
Permission: This 1938 issue of Radio News magazine would have the copyright renewed in 1966. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1965, 1966, and 1967 show no renewal entries for Radio News. Therefore the magazine's copyright was not renewed and it is in the public domain.
Usage Terms: Public domain
License: Public domain
Attribution Required?: No
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