File:Five tube TRF receiver circuit 1924.png

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Captions

Captions

Five tube TRF radio receiver

Summary

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Description
English: A typical tuned radio frequency (TRF) radio receiver circuit from 1924. The TRF circuit, invented in 1916 by Ernst Alexanderson, was widely used in quality radios from about 1920 into the 1930s when it was replaced by the superheterodyne. This example uses 5 triode vacuum tubes: 2 radio frequency (RF) amplification stages, a grid-leak detector stage, and 2 transformer coupled audio amplifier stages. The 3 variable tuning capacitors had to be tuned in tandem. This circuit uses two "B" supply voltages: 90V for the other tubes, and 22.5V for the detector tube because "soft" tubes with some gas in them were used for detectors, which could not tolerate more than 30V on the anode without ionizing. To prevent parasitic oscillations the circuit uses a "stabilizing" potentiometer between the filament rails.

Alterations to image: replaced speaker jack at right end with speaker, and added labels
Date
Source Retrieved January 26, 2016 from The Wireless Age magazine, The Wireless Press, Inc., New York, Vol. 11, No. 12, September 1924, p. 60 on http://www.americanradiohistory.com
Author Unknown authorUnknown author

Licensing

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Public domain
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:Five_tube_TRF_receiver_circuit_1924.png

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