Launched in 1973 at the height of the Cold War, The Buzzer (as it has been nicknamed by radio amateurs and listeners) is a ghost radio station that has been broadcasting bizarre transmissions non-stop on 4625 kHz ever since. It broadcasts a sonar-like sound, interspersed with pauses, the purpose of which is not known; sometimes short voice messages in Russian are broadcast. Over the years, the community of radio amateurs and listening enthusiasts has monitored the transmissions and found technical flaws, such as when in 2010 the transmissions were interrupted for a day and two days later voices were heard in the background, as if a microphone had been left open. The Infinity News article reconstructs the history of “The Buzzer”, while other details can be found on Wikipedia.
After 27 years Radio Liberty returns to speak to Hungarian citizens: on 08th September 2020 it opened an editorial office in Budapest, given the political involution in the country. Premier Viktor Orbán has put more and more stress on democracy and has plunged Hungary into 89th place in the press freedom index produced by Reporters sans Frontières. But things are not simple: the American ambassador (President Donald Trump is in ideological harmony with Orbán) has asked the broadcaster (who declares not to be pressured) to be sympathetic to the Hungarian premier. More info here and here.