File:Experimental superheterodyne receiver 1923.jpg
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Captions
Summary
[edit]DescriptionExperimental superheterodyne receiver 1923.jpg |
English: Early portable 9 vacuum tube superheterodyne radio receiver on table, 1923, showing examples of antique radio components used. Built by W. H. Blucock in England and displayed at the 1923 Radio Fair, Hotel Imperial, London, it received broadcast stations from as far away as San Fransisco. The superheterodyne circuit, used in virtually all modern radios, was invented in 1918 by Major Edwin Armstrong while he was stationed with the Signal Corps in France during World War 1. This example was built with early triode vacuum tubes. It consists of a mixer and local oscillator section (left), 5 RC-coupled IF amplifier stages and a detector (right). The low gain achievable with the triode without instability made many amplification stages necessary. The round adjustable coils (left, center) used to tune the set were called "variometers". The long cylindrical segmented component visible in the background is a "B" battery used to provide the plate voltage of 40 - 150 V. It consists of a stack of individual cells, with taps allowing the voltage to be adjusted by cutting in different numbers of cells. The intermediate frequency was probably around 50-75 kHz. |
Date | |
Source | Retrieved February 21, 2014 from Radio World, Hennessey Radio Publication Corp., New York, Vol. 2, No. 20, February 10, 1923, p. 12 on Google Books |
Author | Credited to International Newsreel Photos |
Licensing
[edit]Public domainPublic domainfalsefalse |
This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1929.
Public domain works must be out of copyright in both the United States and in the source country of the work in order to be hosted on the Commons. If the work is not a U.S. work, the file must have an additional copyright tag indicating the copyright status in the source country.
Note: This tag should not be used for sound recordings.PD-1923Public domain in the United States//commons.wikimedia.org/wiki/File:Experimental_superheterodyne_receiver_1923.jpg |
Annotations InfoField | This image is annotated: View the annotations at Commons |
Local oscillator tube
Mixer tube
Tuning capacitor
Tuning capacitor
Tuning variometer coil
5 stage IF amplifier
Detector tube
"B" battery
Tuning variometer coils
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