Amateur radio calculations. Schemes, articles of the Free Technical Library

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Amateur radio calculations. Schemes, articles, descriptions

Free library / Schemes of radio-electronic and electrical devices

Amateur radio calculations

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Tuning antennas with a frequency response meter

HF Antenna Section. When establishing short-wave antennas, you can use the frequency response meter (X1-19B, X1-7B). Its output is connected to the input through the RF head (Fig. 1), and an antenna is connected to the connection points. Tuning begins with determining the resonant frequency of the antenna. Depending on the type of antenna, either a hump (wave vibrator and other antennas with high input impedance at the resonant frequency) or a dip (half-wave vibrator, antennas derived from it) will be observed on the screen. By adjusting the antenna, they ensure that the maximum (minimum) of the curve on the frequency response meter screen coincides with the middle of the operating range. Frequencies are controlled by labels on the screen. An approximate view of the frequency response of the Ground PIane antenna (without feeder) for the 14 MHz band is shown in Fig. 2 ... >>

Electronic ballast in a luminaire with two 6 W fluorescent lamps

Section Ballasts for fluorescent lamps. The basis of the lamp, the scheme of which is shown in Fig. 3.74, - blocking generator on the transistor VT3. Resistor R7 limits the base current of the transistor. Diode VD1 protects the device from being connected to a power source (battery) in the wrong polarity. Light sources are two connected in series linear LL EL1 and EL2 with a power of 6 W each (for example, Chinese TS F6T5). The luminaire has also been tested with single LLs with a power of 6 and 18 watts. According to the ratio of brightness and current consumption, the choice was made in favor of two 6 W LLs. The low battery indicator is optional (all the elements included in it can be omitted from the board), but it is very useful, especially when using a relatively small capacity battery (for example, a motorcycle battery) ... >>

Aluminum soldering

Section Ham Radio Technologies. For soldering aluminum with conventional tin-lead POS solders, the method proposed by foreign radio amateurs and verified by the author of this note, which is as follows, can be recommended. Liquid mineral oil is applied to the aluminum in the soldering bridge, and the surface of the aluminum under the oil layer is cleaned with a scraper or a knife blade to remove the existing oxide film. Solder is applied with a well-heated soldering iron. For soldering thin aluminum, a soldering iron with a power of 50 W is sufficient, for aluminum with a thickness of 1 mm or more, it is desirable to use a soldering iron with a power of 90 W. If the solder does not adhere to the metal, the tinning process must be repeated. ... >>

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Articles on amateur radio calculations

Articles on amateur radio calculations; descriptions of amateur radio calculations: 40 articles

Radio amateur calculations (collection of articles)

Articles on amateur radio calculations; descriptions of amateur radio calculations: 20 articles

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Researchers from McMaster University (Canada) have identified an antibacterial compound produced by cannabis that could serve as the basis for the development of new drugs.

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The scientists focused on a non-psychoactive cannabinoid called CBG as it had the most promising activity. To conduct research, it was synthesized.

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