Radio Free Europe chief quitting

James F. Brown has resigned as director of Radio Free Europe because of ''political differences with the way the Reagan administration is now directing the radio,'' he said.

The 26-year veteran of RFE served as research head of the Munich-based US station for 18 years before becoming its director in 1976, Monitor contributor Anne Colamosca reports.

Mr. Brown said from Munich that ''a number of exile organizations have joined in the political fray here and are pushing for a harder line inside the radio.'' He plans to stay on six months as a consultant.

Mr. Brown is highly thought of by many academics specializing in East European politics. For example, a recent RFE study, ''The Strikes in Poland,'' has been praised for its well-documented research on Solidarity's role in Poland during the summer of 1980.

In the decade since Sen. J. William Fulbright came within a hair of shutting it down with proof that it was being covertly financed by the CIA, RFE has slowly turned itself into a more middle-of-the-road station.

The immediate reason for Mr. Brown's decision to resign was that the Reagan administration's Board of International Broadcasting, which oversees RFE, refused to approve Brown's choice of Josef Schneider to head the RFE's Czechoslovakian news service. (RFE broadcasts news and commentary daily to five East European countries - Czechoslovakia, Hungary, Romania, Bulgaria, and Poland.)