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"Wavescan" is a weekly program for long distance radio hobbyists produced by Dr. Adrian M. Peterson, Coordinator of International Relations for Adventist World Radio. AWR carries the program over many of its stations (including shortwave). Adrian Peterson is a highly regarded DXer and radio historian, and often includes features on radio history in his program. We are reproducing those features below, with Dr. Peterson's permission and assistance.

Wavescan, February 3, 2013

100 Years of Wireless & Radio in Bulgaria - Pt. 3: The Early Shortwave Scene

Thus far, in our continuing story about the 100 years of wireless & radio in the European nation of Bulgaria, we have presented the early wireless scene, and the story of early radio broadcasting on longwave & mediumwave. In this episode, the 3rd, we now present the interesting story of early shortwave broadcasting, and we pick up this story in the year 1926. That's when the Bulgarian government began to give attention to the need for new radio equipment.

During the following year, a contract for this new radio equipment was awarded to the Marconi company in England; and 2 years later, that is in 1929, 3 new radio transmitters were installed at a location near the Sofia railway station, and activated. These units were listed as:

Morse & Speech Longwave 105 kHz
Communication Shortwave 7460 kHz
Communication Shortwave 14970 kHz

However, as time went by, these 3 transmitters fell into disuse, and were seldom activated, and by 1935, only one was usable. Towards the end of that year, the transmitter engineers upgraded the usable shortwave transmitter at the radio site near the railway station. They made a power increase to 1-1/2 kW and adapted it for the broadcast of speech & music.

On November 12, 1935, the 1st test transmissions were made from this modified equipment, with emissions on 14970 kHz during the day and 7460 kHz at night. Then a few weeks later regular programming was inaugurated, with the relay of broadcasts from the Sofia mediumwave station each Sunday. This new series of program broadcasts began on Sunday January 19, 1936.

The broadcast of programming for an international audience began from this renovated shortwave transmitter LZA on Tuesday May 24, 1936, with a regular daily relay in the Bulgarian language from mediumwave Radio Sofia for the benefit of Bulgarians abroad. In addition, a regular bulletin of news in the international auxiliary language, Esperanto, was introduced at the same time.

Then, on May 1 of the following year, Radio Sofia went truly international, with the introduction of programming in 4 more European languages; English, French, German & Italian. Turkish was added in early 1938.

However, on April 15, 1938, the usage of shortwave for the dissemination of their radio programming was terminated in favor of the powerful new 100 kW mediumwave transmitter located at Vakarel, 15 miles south east of Sofia. The shortwave transmitter was then employed only for communication usage.

However, with the political scene heating up in continental Europe, usage of the shortwave transmitter was re-activated in November 1938 and the broadcast of radio programming on shortwave was resumed. Hostilities broke out in September 1939, and soon afterwards the shortwave service via the 1-1/2 kW transmitter LZA in Sofia was terminated.

Interestingly though, an international radio monitor in the United States logged a shortwave station that was located in Sistova, Bulgaria in June 1939. According to the report at the time, this station was carrying radio programming on 9420 kHz. At this stage, the main shortwave station in Sofia, LZA, was not on the air with program broadcasting.

We would suggest that this shortwave station at Sistova must have been a low powered unit, probably a communication station at around 1 kW. The programming at the time must have been either a relay link for one of the mediumwave stations in Bulgaria, or a test transmission to observe whether this station could be taken over in an emergency as a regular broadcasting station.

The 1st known printed logging for shortwave station LZA in Sofia, Bulgaria was by an Australian listener who heard the station on 14970 kHz in September 1936. The identification announcement was given as Radio Garata. The last known logging, just 3 years later, was also in Australia soon after the war started when the station was logged on 8500 kHz.

At the end of the year 1939, the following list of mediumwave & shortwave stations were on the air in Bulgaria:

Shortwave Sofia 1.5 kw 8500 kHz
Sistova 9420 kHz
Mediumwave Vakarel 100 kw 850 kHz
Sistova 1187 kHz
Varna 2 kw 1276 kHz
Stara Zagora 2 kw 1402 kHz