The Orlunda longwave transmitter was a longwave broadcast facility in central Sweden which broadcast Sveriges Radio Programme 1 from 1962 to 1991. The facility is currently in use as a museum. Planning and construction The Swedish Telecom Administration Board and its technical department, Televerket, had begun plans for an upgraded longwave transmitter to serve central Sweden as early as the 1940s. The original facility, located in central Motala, was both antiquated and poorly situated; the transmitter was inefficient and staff were needed on site to operate it day and night, and signal fading occurred as close as 80 kilometres away. After numerous studies it was determined that a site east of the town of Vadstena would provide a clear signal to the surrounding area. Construction began in 1958; engineer Folke Strandén designed a ring antenna system consisting of a central mast surrounded by five antennas, to be connected to two 300 kW Compagnie Français Thomson Houston (CFTH) transmitters. The station itself was built underground in a windowless concrete bunker with 1.5-metre thick walls designed to survive a Soviet air attack. The bunker would host the power supply, transmitters, transformers, and a V-12 diesel engine to be used as a backup generator. All cables leading to and from the facility were likewise buried underground. Technical specifications The two transmitters could be used either independently or together, and featured a CFTH specialty, steam-cooled tubes called "Vapotrones". They had a power efficiency of 66%. The antenna system was designed to produce a ground wave intended to prevent interference with distant transmitters on the same frequency. The transmitter also broadcast a signal at a 40° angle; this did not affect reception, but its effect on distant stations is unknown. Programs were sent to the facility by telephone cable and were amplified before transmission. The centre antenna, 250 metres in height, was located near the station and the secondary antennas, 200 metres each in height, were arranged in a ring surrounding the station; each secondary antenna was 630 metres from the centre antenna and 630 metres from its neighbours. Construction was completed in 1961 and the station was officially inaugurated by HRH Prince Bertil in May of that year. The station began broadcasting in 1962, after the necessary tests and adjustments had been conducted. Operations The station originally broadcast Programme 1 of Sveriges Radio, the Swedish national broadcaster, on 191 kHz. Its improved coverage and