File:Tuned circuit of shortwave radio transmitter from 1938.jpg
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Summary
| Description |
English: Output tank circuit (LC circuit, tuned circuit) of power amplifier of shortwave amateur radiotelegraph transmitter from 1938. It consists of an inductor (coil, top) connected in parallel with a variable capacitor (bottom). It serves as a bandpass filter, removing any harmonic frequencies from the output so they will not be radiated by the antenna. Since the output power is 1 kilowatt the voltage on the circuit is several thousand volts, so to prevent arcing the capacitor plates are more widely spaced than a low voltage capacitor, and the coil is mounted on standoff insulators. The tuned circuit must have a narrow bandwidth (high Q) to filter the narrow CW signal, and the coil shows high Q construction: it is made of a single layer winding with turns separated to reduce losses from proximity effect, of thick silver-plated wire to reduce losses from skin effect, suspended in air without a coil form to reduce dielectric losses. |
| Date | |
| Source | Original image: Retrieved 7 June 2023 from Smith, W. W. 1938 The Radio Handbook, Radio, Ltd., Los Angeles, p.343 fig.24 on archive.com. Cropped out rest of circuit. |
| Author |
Original image: W. W. Smith This version: Chetvorno |
| Permission (Reusing this file) |
This book published in the US in 1938 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 The Radio Handbook. Therefore the work's copyright was not renewed and it is in the public domain. |
| Other versions | Vacuum tube HF300 shortwave RF power amplifier from 1938.jpg picture of the complete amplifier |
Licensing
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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.
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 23:57, 7 June 2023 | | 383 × 294 (58 KB) | Chetvorno | Uploaded a work by W. W. Smith from Retrieved 7 June 2023 from [https://archive.org/details/The_Radio_Handbook_5th_edition_-_Smith_Dawley_1938/page/342/mode/2up Smith, W. W. 1938 ''The Radio Handbook'', Radio, Ltd., Los Angeles, p.343 fig.24] on archive.com with UploadWizard |
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