File:First Neutrodyne radio receiver closeup.jpg
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[edit]DescriptionFirst Neutrodyne radio receiver closeup.jpg |
English: The first Neutrodyne radio receiver, built by Louis Hazeltine at Stevens Institute of Technology and presented at the March 2, 1923 meeting of the Radio Society of America. The Neutrodyne was a modification of the tuned radio frequency (TRF) receiver which neutralized feedback in the triode vacuum tube, preventing oscillations which caused howling and squealing noises which plagued this type of receiver, and also radiated interfering radio signals which could interfere with other receivers. The oscillations were caused by the large capacitance between the grid and plate electrodes in the triode, which could feed energy back from the output to the input. The Neutrodyne circuit prevented oscillation by a second feedback path which fed some of the plate signal back to the grid with opposite phase, to cancel the interelectrode feedback. This prototype had five vacuum tubes: two stages of tuned radio frequency amplification, a detector, and two stages of audio amplification. The three interstage coupling coils are visible, mounted at an angle to minimize magnetic coupling which could also cause feedback and oscillations. The neutralizing signal for each stage is taken from a reverse-phase winding on each coil. The neutrodyne was widely used until the 1930s, when it was replaced by the superheterodyne receiver Caption: "The new Hazeltine circuit receiver. Five tubes are used and the circuit is incapable of regeneration or oscillating, which is the cause of much interference in the present-day receivers, especially when many are located in a small district, such as New York. |
Date | |
Source | Retrieved January 28, 2014 from Radio World magazine, Hennessy Radio Publications Corp., New York, Vol. 2, No. 24, March 10, 1923, p. 7 on Google Books |
Author | Unknown authorUnknown author |
Permission (Reusing this file) |
This 1923 issue of Radio World magazine would have the copyright renewed in 1951. 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 1950, 1951, and 1952 show no renewal entries for Radio World. Therefore the magazine's copyright was not renewed and it is in the public domain. |
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[edit]Public domainPublic domainfalsefalse |
This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties. العربية ∙ Deutsch ∙ English ∙ español ∙ français ∙ galego ∙ italiano ∙ 日本語 ∙ 한국어 ∙ македонски ∙ português ∙ português do Brasil ∙ русский ∙ sicilianu ∙ slovenščina ∙ українська ∙ 简体中文 ∙ 繁體中文 ∙ +/− |
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