English: Single tube trioderadio receiver from 1924, with parts labeled. Invented by Lee De Forest with the triode around 1912, this was the earliest vacuum tube receiver. The tube serves as a grid-leak detector to rectify the radio signal to extract the audio modulation (sound) from it, and also amplify it. The grid leak, a megohm resistor and capacitor in parallel connected in series with the grid, served to bias the grid with a negative DC voltage near cutoff, so it only conducted current on the positive half cycles of the RF cycle. It used a UV-200 tube.
Alterations to image: changed two of the labels to be more informative, added image of vacuum tube from another picture (in original image the tube socket is shown empty).
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