Radio in Bulgaria Celebrates 100 Years

It was on September 25, 1921, that the very first radio broadcasting event took place in Bulgaria, and they celebrated the 100th anniversary of this historic event on September 25, 2021, just three months back. Their very first radio broadcast was the live relay of a program from Germany via a Morse Code transmitter that was specially modified for the event.

Boris III of Bulgaria, a coloured photograph taken in Sofia in 1920’s
Wikipedia: By Unknown author – Reprinted with permission from, CC BY-SA 4.0, Link

The broadcast of the radio program from Germany was announced in advance, a program in both German and Russian, and it was transmitted from the German radio station at Nauen, near Berlin. Back then, the German station at Nauen operated on several different experimental longwave channels under the internationally recognized callsign POZ.

The low powered modified Morse Code transmitter in Bulgaria was installed in a government building near the railway station in Sofia, and the reception and the relay of the broadcast from Germany was a successful and historic radio event. His Majesty the late King Boris 3 heard the historic relay broadcast via the modified radio transmitter in his own capital city Sofia with the use of what we would call today a set of antiquated headphones.

That first experimental radio broadcast was aired on September 25, 1921. The first transmission at the beginning of what became a regular radio broadcasting service was inaugurated on mediumwave in Sofia eight years later on November 24, 1929. At the same time, a home service on shortwave service was commenced with the use of two Marconi communication transmitters, on 7460 kHz and 14970 kHz.

Seven years later, one of the shortwave transmitters was renovated and an international service was inaugurated under the callsign LZA on May 24, 1936. On air programming was for the benefit of Bulgarian citizens living abroad and it was presented in two languages, Bulgarian and Esperanto.

Studios of Bulgarian Radio in the 1930s. Photos from the website

Back during the World War 2 era, the shortwave transmitters in Bulgaria were taken into use for the relay of programming from other countries. The relay of programming from Radio Moscow in Russia, as well as the Radio Espana Independente service, began during the European war.

For a period of 8 years beginning in the latter part of the year 1953, the programming of Radio Tirana Albania also was noted on relay from Radio Sofia in Bulgaria. As stated in the American radio magazine, “Radio News”, this half hour program was on the air on Sundays only, at MN30 UTC on 9700 kHz. According to the 1956 edition of the WRTVHB, the frequency 9700 kHz was emitted by a 100 kW transmitter located at Stolnik in Bulgaria.

Early images from the website

Interestingly, the relevant issues of the WRTVHB during this era do not list the Bulgarian relay from Radio Tirana, though the actual time slot in the service to North America on 9700 kHz is simply shown as vacant. In November, 1961, two new transmitters at 50 kW were inaugurated for Radio Tirana at Sijak in Albania, and the weekly relay via Radio Sofia Bulgaria came to a quiet end.

Radio Sofia in Bulgaria began the broadcast of programming on behalf of the Voice of America in 1993. However, all usage of shortwave for the broadcast of Home Service and International Service programming came to an end around the turn of the century.

These days, there is just one radio broadcasting station on the air in Bulgaria, and this is the powerful 200 kW government owned mediumwave transmitter at Vidin on 576 kHz. The city of Vidin is located 50 miles north of the national capital Sofia, and the mediumwave transmitter gives wide coverage throughout Bulgaria and beyond. As would be expected these days, there is a huge number of government owned and commercially operated FM stations throughout the entire country of Bulgaria, all operating in what we would call the standard international FM Band 2.

During 2011, BNR experimented with DRM digital transmissions on shortwave.
This broadcast of BNR Digital on 9700 kHz from Kostinbrod was received well in New Zealand.
© Radio Heritage Foundation, Chris Mackerell Collection

Shortwave Radio Sofia was noted in earlier years as a prolific verifier of listener reception reports, though they did operate under their own distinct procedures that were a little different from what other major stations had implemented. In earlier days, Radio Sofia shortwave requested listeners to submit a sequence of reception reports within a stated period of time, and these reports would then be verified by a series of six QSL cards in a progressive sequence.

After six QSL cards had been sent to a listener, then a Diploma was available; and there were three progressive diplomas, Bronze, Silver & Gold. In order to obtain a Gold Diploma, at one stage it was necessary for the listener to send in a total of 63 reception reports within a period of somewhere around 70 weeks, a total time period of nearly 1½ years.

A selection of Radio Sofia QSL cards from the 1970s & 80s. © Radio Heritage Foundation, Raplh Sutton & Chris Mackerell Collections

However, Radio Sofia did also acknowledge many reception reports with the regular processing of QSL cards that were not linked to the Diploma system. In addition, they also sent out New Year and Spring greeting cards, picture cards of Bulgaria, and letters of greeting that described various events and places of interest in their country.

We congratulate Bulgaria on the occasion of the one hundredth anniversary of radio broadcasting in their country.

This feature was written by Adrian Peterson and originally aired on Adventist World Radio’s “Wavescan” DX program of December 5, 2021

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