Author: Petrosani Children's Club
Quarterly magazine of the circle of electronic constructions and amateur radio
Coordinator: Prof. Kovacs Imre - YO2LTF
Did you know that ...? In the early days of amateur radio, long-distance radio links were very rare, and after such a radio link took place, did the correspondents confirm their contact by sending letters to each other?
Today, QSLs serve multiple purposes: are required for various diplomas, confirm radio links, are decorative and evoke memories. Today, radio links can also be confirmed by electronic QSL, e-QSL.
The structure of the magazine
1. Visiting the YO8RAA (Mircea Popel)
In his long activity as an amateur radio, Mircea made thousands of connections confirmed through QSLs. We talked about satellite links, about computer programs for watching them, about digital communications for radio amateurs.
Analog or digital communications are a necessity and a reality of the XNUMXst century. In special situations (natural disasters, disasters, etc.) "alternative communications" is perhaps the only solution and in this sense, radio amateurs through the technical equipment they have can be an alternative not to be neglected…
2. QSL cards
Amateurs send QSL cards to confirm a radio link. It is often said that QSL is the final sign of courtesy of a radio link and indeed, millions of QSLs are sent each year.
The term "QSL" comes from the Q code "Confirm receipt" and the primary purpose of the QSL is to confirm contact by radio wave, so it must contain records all radio-specific elements:
- Own station code;
- The call sign of the corresponding station;
- UTC date and time;
- The band in which the connection was made;
- Emission class used;
- RTD control of the correspondent's signal reception;
- QTH-own station locator;
3. 200W amplifier
The amplifier presented has as main component the integrated circuit TDA2020. This circuit made many years ago is still suitable today for making "low cost" audio amplifiers.
The main parameters are:
- external load (speakers) between 4..16 Ohm;
- supply voltage between 24 - 36V;
- maximum current absorbed from the source - max. 5A;
- guaranteed frequency band - 20… 20000 Hz.
4. History of the Internet
In the 50s, the Cold War years, American Department of Defense realized that the existing communication systems at the time would be effective in the event of a nuclear war.
It had become obvious that maintaining communications was vital. In the year 1962, Paul Baran, a researcher at a government institution, described a solution to the problem in "Distributed Communication Networks." He proposed a nationwide system to connect computers using a decentralized network, so that even if one or more major nodes were destroyed, the rest would be able to maintain communications, dynamically adjusting connections.
The proposal was discussed, developed and expanded by various members of the computer science community. In 1969, the first packet switched network was founded by ARPA (Advanced Research Projects Agency)...
5. Nicholas Tesla
A special case, out of the ordinary, is that of Nikola Tesla, who with his brilliant inventions is an often misunderstood or even "forgotten" subject of current science. However, we must admit that some of his countless discoveries are widely used today, but others have been "lost" or "forgotten."
It is interesting that, if we have the curiosity to look in a technical encyclopedia with university pretensions, next to its name we will find written only a few lines, when in fact the Tesla coil - his most spectacular invention is presented as a kind of "transformer", without showing the operating principle or its amazing possibilities.
6. Very high voltage generator - TESLA
One of the most interesting applications of the controversial discoveries of the "brilliant" Tesla is high voltage generator, using electrical resonance. The assembly shown is quite simple. Using a usual electronic tube of the type PL50, powered only at 24 Vac, is obtained due to the resonance of the anodic circuit a voltage of thousands of volts. This can be easily highlighted with a neon tube…
- What is the deepest lake on the planet?
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- What is the highest peak on the planet?
- What is the driest region in the world?
- What is the largest salt dessert on the planet?
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