File:120 MHz Lecher line oscillator 1934 closeup.png
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| Description |
English: An experimental 120 MHz vacuum tube amateur radio transmitter with a Lecher line tank circuit, built by George W. Shuart, W2AMN, in 1934. During the 1930s research went into extending the frequency of short wave transmitters into the VHF and UHF ranges. The conventional vacuum tube feedback oscillators operated poorly at these high frequencies because of excessive capacitance and inductance of tube electrodes and connecting wires. In this circuit, to address this problem, the type 801 triode tube (bottom) is mounted upside down with the grid and plate terminals connected directly to two parallel 1/4" copper tubes, forming a resonant half-wave transmission line stub (Lecher line) which serves as the tank circuit and feedback path. The two wires in the foreground attached to the Lecher rods provide the grid and plate DC bias through chokes. They are attached at the voltage node on the line, where the AC voltage goes to zero, to reduce filtering needed. The circuit produced power from 120 to 240 MHz and could be received at 14 miles. |
| Date | |
| Source | Retrieved March 21, 2014 from George W. Shuart, "More Power on 2.5 Meters with Triodes" in Short Wave Craft, Popular Book Corp., New York, Vol. 5, No. 7, November 1934, p. 399 on American Radio History website |
| Author | George W. Shuart |
| Permission (Reusing this file) |
This 1934 issue of Short Wave Craft magazine would have the copyright renewed in 1962. 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 1961, 1962 and 1963 show no renewal entries for Short Wave Craft. Therefore the magazine's copyright was not renewed and it is in the public domain. |
| Other versions | 120 MHz Lecher line oscillator 1934.jpg |
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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. 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 (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
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| current | 11:15, 22 March 2014 | | 389 × 785 (47 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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