File:1 kW RF amplifier for 10 & 20 m 1938.jpg
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Captions
Radio transmitter final amplifier 1938
Summary edit
| Description |
English: An RF final amplifier for a shortwave amateur radio transmitter from a 1938 radio magazine. Called the "10-20", sold by Radio-Television Supply Co. of Los Angeles, it could deliver 1 kilowatt continuous wave or 600 watts amplitude modulation on the 10 or 20 meter band (15 or 30 MHz) using two type 100TH triode vacuum tubes. The two triodes were operated in push-pull, driving the resonant tank circuit visible at right consisting of two parallel plate capacitors connected to the air core inductor. It came with 4 plug-in coils to cover the two bands, and sold for $32.50 in kit form without tubes, and $37.50 wired. |
| Date | |
| Source | Retrieved Sepember 7, 2014 from Radio magazine, Technical Publishers, Inc., Los Angeles, No. 229, May, 1938, p. 92 on American Radio History website |
| Author | Unknown author |
| Permission (Reusing this file) |
This image is from an advertisement for the Radio-Television Supply Co. without a copyright notice published in a 1938 magazine. In the United States, advertisements published in collective works (magazines and newspapers) are not covered by the copyright notice for the entire collective work. (See U.S. Copyright Office Circular 3, "Copyright Notice", page 3, "Contributions to Collective Works".) Since the advertisement was published before 1978 without a copyright notice, it falls into the public domain. |
Licensing edit
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This work is in the public domain in the United States because it was published in the United States between 1929 and 1977, inclusive, without a copyright notice. For further explanation, see Commons:Hirtle chart as well as a detailed definition of "publication" for public art. 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 (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 11:56, 7 September 2014 | | 531 × 378 (38 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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