(Translated from French)
The country’s last medium-wave transmitter celebrates its 50th anniversary. It still broadcasts the BNR Horizon program on 576 kHz. РПС-1 Водна БНР is located between the villages of Vodna and Sratsimirovo, in the northwest of the country (43°50’13.8″N 22°42’56.1″E).
It was built in 1973, with the help of Russian specialists and all equipment and antennas were Russian-made.
Two Russian transmitters with a power of 500 kW were installed.
Vidin had the best medium wave antennas in Bulgaria.
One operated on 576 kHz. It was a 260 meter single mast ARPT with adjustable current distribution (ARPT). This type of antenna improves the circular radiation pattern (reduces radiation in the vertical direction and increases it in the horizontal direction), increases the gain and has an anti-fading effect. This transmitter broadcasts the program “Hristo Botev” on the BNR until 2010.
The second system is a square antenna whose direction of emission can be changed and the four masts measure 135 meters high. It broadcast radio Stara Zagora on 1224 kHz. It was used for international broadcasts to Albania and Turkey. It is now used on 576 kHz to target southwest Bulgaria. The transmitter covers a large part of Bulgarian territory,
A third transmitter had been installed in the late 1970s. It was a 40 kW Bulgarian transmitter, which broadcast the BNR’s “Horizon” program on 1017 kHz using a quarter-wave antenna, it was switched off around 2000.
From the year 2000, the BNR wanted to stop medium waves. After 2010, the power was reduced to 300 kilowatts and its final shutdown took place in 2012.
It was a brief stop for the Vidim transmitting center, it was chosen to become the national medium wave transmitter. In 2013, one of the old 576 kHz tube transmitters was dismantled to make way for a transistorized Thomson with a power of 400 kW. The other Russian-made transmitter was retained as a backup. The BNR very quickly realized that a back-up had no use compared to Thomson’s S7HP, especially since it very quickly operated at a reduced power of 200 kW.
From April 1, 2013, he will be officially responsible for broadcasting the Horizon program 24 hours a day. Finally, it was the following week that it entered regular service, following problems connecting the new transmitter to the old antenna.
It was planned to continue using the 260 meter mast for broadcasting on 576 kHz. It quickly became clear that using the second antenna, which is directive, would be a better solution if we wanted to cover the whole of Bulgaria.
The transmitter covers a large part of Bulgarian territory, however, the signal is very weak during the day in the south, east and north-east of Bulgaria.
The 260 meter mast was destroyed because it no longer had any use.
Radio Magazine FB group (2023-10-20)