Thursday, December 29, 2022

History of Bulgaria's Vakarel transmitting station

From the script of AWR "Wavescan" DX Program   
On this occasion here in Wavescan today, we present the story of the huge radio broadcasting station that was erected at Vakarel back in the era before the beginning of World War II. Vakarel is a small town with a population of less than 2,000, some 25 miles southeast of the national capital Sofia.

Both the major national highway system and the electrified railway system run through the Vakarel area. A major highlight in the area was the tall radio tower that was erected a mile distant from the village of Vakarel some 85 years ago.

It was on Wednesday 13 October 1937, that the huge new radio broadcasting station was officially dedicated at Vakarel, with the intent of gaining nationwide coverage on mediumwave and longwave from one location. Test broadcasts from the new Telefunken transmitter began six weeks later, on 17 November with 100 kW on 850 kHz.

At the time of construction by Telefunken, the Blaw-Knox radio tower stood at 1160 feet (though some authorities say 705 feet) and for a long period of time, it was the second tallest man-made structure in the world and the tallest in Europe. It was a tourist wonder in that area of forests and undulating hills.

At the time of its demolition, the Vakarel radio tower was still the tallest in Bulgaria. The famous (or as some radio engineers would suggest, infamous) Blaw-Knox diamond-shaped tower near Vakarel was one of four such towers in Europe.

Back in 1937, two-directional antenna systems were erected at Vakarel for use on longwave and mediumwave, though little use was ever made of its longwave capability. One antenna system was made up of three towers, each guyed, and the other system consisted of two towers.

The mediumwave channel initially was 850 kHz, with a power of 100 kW.

During World War II, the 100 kW transmitter was operated at half power, 50 kW, due to the unavailability of spare parts, though still on the same mediumwave channel 850 kHz.

When circumstances in Europe began to settle down after the end of World War II, the power level at the mediumwave transmitter was again restored to its 100 kW capacity. At the same time, the operational frequency was changed to fit in with the mediumwave channel patterns in Europe, and the original 850 kHz channel was modified in favor of the new 827 kHz.

However, when the pattern for mediumwave frequency usage was modified to 9 kHz intervals in Europe in 1978, the Vakarel transmitter was adjusted from 827 kHz to 828 kHz. Back at that era, radio Sofia was on the air via Vakarel with news bulletins in 15 different European languages, including Esperanto.

During the year 1990, a new high-powered 500 kW mediumwave station at Shunem, in the northeast of Bulgaria, was activated on the same channel as Vakarel, 828 kHz. However, the program feed for both transmitters was the same, in the languages of the surrounding countries. At the same time, the power level at Vakarel was reduced from 100 kW to 50 kW.

But changes were on the horizon. The German-made Telefunken transmitter at Vakarel was aging, and a whole nationwide network of FM stations was taking over the radio scene throughout Bulgaria. Both Vakarel and Shunem were inactive in 2011, and finally, the historic Vakarel transmitter was silenced forever three years later, on 31 December 2014.

The three-quarter century-old Blaw-Knox tower stood tall and strong for another six years, as no more than an old tourist attraction. Then two years ago in 2020, a special event amateur station LZ0AA was licensed to transmit 80 meters from the Vakarel Tower, as the final episode of events from this historic landmark.

That was the end. On 16 September 2020, that tower with its 130 tons of steel was dropped.

Gone was the old historic German transmitter, and likewise the old German tower, both of which performed so remarkably well during their 85-year history of mediumwave radio broadcasting. However as a matter of interest, you can search for Vakarel Radio Tower on Google Earth, and there you will see the tower still standing, together with its lengthy shadow.
(via BrDXC-UK 'Communication'/Top News 27 Dec 2022)