Masts of RKS Liblice 2 as viewed from a distance.Close-up view of the masts of the towers.
The RKS Liblice 2 are two 355 m (1,165 ft) tall guyed masts located east of Prague near Liblice, in close proximity of the RKS Liblice 1. These lattice steel towers are built 120 m (390 ft) apart from each other, what formed a slightly directional radiation pattern directed towards Spanish Madrid transmitter on the same frequency. The masts carry a special anti-fading cage aerials. Designed by Jan Šťovíček, these supertall towers currently stand as the tallest towers in the world used for broadcasting in the medium-wave range. RKS Liblice-2 was built in 1976, and is used for broadcasting on 639 kHz, with a period of inactivity from January 2022 to September 2023. During construction, two new transmitter devices of the type Tesla SRV 750 with an output power of 750 kW were installed. At first, these transmitters were switched in parallel for a transmission power of 1500 kW, after 1990 only 750 kW was used for broadcasting. Since 2023, the transmitter broadcasts with only 20 kW of power, a significant lowering. The old transmitter device was replaced with a semiconductor type TRAM one.
History
The Blaw-Knox RKS Liblice was 280.4 m (919.9 ft) tall tower before it was demolished on August 11, 2004, in lieu of the construction of the current towers. The original tower were built in 1936, by Karlova Huť; these towers survived World War II without damages.
Events
On November 23, 1978, the transmission frequency of the new towers, which was 638 kHz since 1950, was changed to 639 kHz in order to fulfill the regulations of "waveplan" of Geneva.
On August 27, 2005, a skydiver jumped off one of the masts after gaining illegal access to it. His parachute became accidentally hooked to a backstage insulator. Fortunately, the incident did not get him too close to the cage antenna of the tower, which would likely have led to his death due to the presence of high frequency currents.
The broadcasts of Czech Radio Prog. 2 ceased at midnight of New Year's Day 2022.
Since September 27, 2023, Country Radio, a private station, broadcasts through this transmitter, replacing the old RKS Zbraslav one, therefore moving from 1062 to 639 kHz. However, it operates at a greatly reduced power of only 20 kW.
