Posted by Robert SP7RB [ rbaleja@mac.com ] on November 11, 2022 at 19:40:55.

In Reply to: Re: 225 kHz posted by John Davis on October 22, 2022 at 18:16:01.

I found a description for you (Google translation). After a long search, make a decision on Solec Kujawski, located in pu− Bydgoszcz Peak, on the site of the former former military ligon. Because this place is not in the price the country's coffin, scientists decided to construction of two masts: 330 m and 289 m, to shape the ray characteristics - nanization allowing for an even surface covering the entire territory of Poland. Direction ma− ximal radiation is oriented in Przemyśl and Lubaczów. Modern equipment has been installed broadcasting company THOMCAST with a modular semiconductor structure. Transmitter with an operating frequency of 225kHz and output power radiated from the 1MW antenna (check - energy efficiency of 90%) consists from three blocks of 400kW coupled power adder. In turn, each of the three transmitting blocks contains as many as 256 semi- no− conductor wave amplifiers Śna, based on MO− SFET in a bridge arrangement. Apply - no newly patented by Thomcast sy− MPMp3 stamp for am− modulation gain plitude. Adopted modulation system after modifying the transmitter will be possible in the future adapted for broadcasting digital. Operation of this new system AM modulation is simply based on computer-controlled such opening on and off the amplifiers so that they can slip to obtain the amplitude envelope of the sy− gnału RF corresponding to the mo− signal dulący m.cz. Also for improvement the efficiency of the station's operation has been applied dynamic level control system DCC carrier wave, as well as a process amplifier sor OPTIMOD, shaping appropriately low frequency modulating input signal abilities. In order to ensure the same the average heat load strengthens - whether the rotary exchange system was used working places of amplifiers with a frequency at 60kHz. In addition, power amplifiers are liquid-cooled, and the same method is solved The cooling capacity allows for quick replacement damaged module without necessity disassembly of the hydraulic system. Too the modular design of the transmitter ensures Flexibility unattainable in tube technology work reliability and reliability, as well as elimination them the concept of "maintenance shutdown", because - I know the failure of one or more RF amplifiers or the whole one block ku, it has practically no effect on the quality continued issue. The station may be working drive non-stop, temporary drop in range no will be noticed. It is also worth mentioning that the low na− collector heel 330V (instead of voltage 15kV anode in tube technology), it also has a positive impact on safety crew. The transmitting devices are multi-level protected against the effects of lightning weather and covered by the system electric shock protection, governed by an extensive com− system computer. The group of transmitting antennas consists of two grounded quarter-wave steel masts with heights of 330m and 289m, set apart at a distance of 330m and kept vertically through five levels of haul-offs in diameter 5cm each. The antenna system includes, in addition to masts, or elements radiate - earthed counterweights also enter electromagnetic gi. They are located around each of the masts, their radius from - says the height of the mast and their composition 120 copper wires are stacked together radially every 3 degrees from the base mast and compact additional ta- dare at a depth of 30 ... 40 cm. Both masts are powered by RF energy. using two coaxial sections a wire lead line with an impedance of 120 Ω. This line is suspended, through insulators, on steel supporting structures 4.5 m high. Highest, non-insulated exhaust levels, are galvanic connection of the masts' tops to the ground, co it is a kind of lightning protection umbrella. The steel elements of the antenna system are protected against corrosion with a zinc coating hot-applied coating, and additionally li− The extractors are covered with a special wax protective paint with white and orange stripes. The antennas are constructed in such a way that that in the future (as in the sender− ku) it was easy to switch to broadcasting digital, because the radio of the future is a digital.

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