August 21, 1986

Ed Debevic's is a zany 1950's diner where the cooks heap on the meat loaf, the waitresses wear saddle shoes and a brightly colored sign reads, ''Ed's Chili Dog: The Cadillac of Chili Dogs.'' A half mile south stands Shaw's Crab House, a dimly lit seafood emporium reminiscent of the haunts that gangsters frequented in the 1940's. On the north side of town, Un Grand Cafe, with its brass fixtures and festive paintings, recreates the fin de siecle gaiety of a Paris bistro. Although very different, these colorful restaurants have two things in common: they usually have lines out the door, and they are owned by Lettuce Entertain You Enterprises, the brainchild of Richard Melman, an irreverent 44-year-old restaurant impresario. Mr. Melman and his chief rivals on the Chicago scene, Larry and Mark Levy, are among the leaders of a small, aggressive group of young restaurateurs around the nation who are putting together empires of 10 or 20 restaurants that place as much emphasis on fun and fanfare as on food.

The General Electric Company is expected next week to name Robert C. Wright, the president of the G.E. Credit Corporation, to replace Grant Tinker this fall as the chairman of NBC, according to network sources. The appointment of a replacement for Mr. Tinker has been a subject of anxiety at NBC because of the merger between General Electric and NBC's parent company, RCA, and the disclosure early this year by Mr. Tinker of his intention to leave the network after having crafted its rise from a ratings loser to the most successful of the three major networks. Mr. Tinker had publicly expressed a desire that his successor be chosen from among the ranks of the current NBC management. But it became clear this summer that the G.E. chairman, John F. Welch Jr., intended to choose Mr. Tinker's replacement from outside NBC.

Because of an editing error, an interview in some copies of Business Day yesterday with James E. Olson, chief executive of the American Telephone and Telegraph Company, contained contradictory statements about his age. The executive, who has been with the company 43 years, is 60 years old.

''The Soviet Union is confident that agreements on ending nuclear tests can be reached speedily and signed already this year at the Soviet-American summit meeting.'' - Viktor F. Isakov, a Soviet official in Washington. [ A9:1. ]

The Commerce Department said today that it had started an inquiry into a suspected leak to the financial markets of its revised economic growth rate for the second quarter, which was announced at 8:30 Tuesday morning. Sherman M. Funk, the department's inspector general, said he had begun the investigation, but he declined to comment on particulars except to note that ''the circumstances give rise to a supposition that there may have been a leak.'' He added in a telephone interview: ''Obviously there is always the possibility there may have been a lucky guess.'' The move came as the department heard from financial market sources in both New York and London that the sharp downward revision in the growth rate to six-tenths of 1 percent, from 1.1 percent, had been known by some market participants as early as Monday afternoon.