The Soviet Union on Tuesday stopped jamming Radio Liberty broadcasts for the first time in 38 years, officials said today, as thousands of jamming transmitters blocking most Western broadcasts into the Soviet Union and Eastern Europe were silenced. Jane Lester, spokeswoman for Radio Free Europe-Radio Liberty, said the service monitored all of its broadcasts overnight and found no jamming except for Radio Free Europe transmissions to Czechoslovakia and Bulgaria. ``This is really a momentous event,'' said Stanley Leinwoll, U.S. engineering director for the services in New York City. He said between 2,000 and 2,500 jamming devices were shut down in the Soviet Union, along with others run by Eastern European governments. The lifting affected most Radio Free Europe, Radio Liberty and Radio Free Afghanistan services of the U.S. government along with most Israeli KOL transmissions and West German Deutsch Velle broadcasts beamed toward the Soviet Union and Eastern Europe, said Beth Knisley, a spokeswoman for the Voice of America. Radio Liberty, run by the U.S. government, broadcasts in native languages to the Soviet Union and Eastern Europe from Munich, West Germany. VOA also broadcasts to those areas but operates separately from Radio Liberty. Only the VOA and West German broadcasts into Afghanistan and U.S. broadcasts into Czechoslovakia and Bulgaria remained jammed last night, Ms. Knisley said. She said the Soviets have not said why the jamming was stopped but added, ``It saves them a lot of money, though.'' The Soviets stopped jamming nearly all broadcasts by VOA, which transmits in 43 languages throughout the world, in May 1986. Last Jan. 1, Polish jamming of VOA also stopped. The Soviets have been jamming Radio Liberty continuously for more than three decades. Ms. Knisley said one listener who talked to a VOA researcher said Tuesday he had picked up a broadcast for the first time since the 1950s. She said she did not know where the listener lived. VOA is part of the United States Information Agency, but Radio Free Europe-Radio Liberty operates as a separate government radio service. ``The jamming stopped as of last night about 9 p.m. (4 p.m. EST),'' Radio Liberty spokesman Bob Redlich said in Munich. Radio Liberty transmits news, music and information programs to the Soviet Union in more than a dozen languages. Radio Free Europe transmits to the other Soviet Bloc countries, including Poland, Czechoslovakia, Hungary, Romania, and Bulgaria in their own languages. Radio Free Europe began operating in 1950; Radio Liberty started its tranmissions to the Soviet Union in 1951.