What was going on when I was born?

-------------------------------------------------------------------- Jim Kemp is an editor and writer in the design field. By JIM KEMP THE next time you see a room of antique furniture look again. Those ''antiques'' may represent a growing phenomenon: copies of American furniture from museum collections. These museum-sponsored ''authentic reproductions'' offer historic American designs at relatively affordable prices.

IT wasn't until Lisa Cowen, a designer, had looked all over town for a new apartment that she decided to stay in the one she had lived in for ll years. ''I was separated and getting divorced,'' Mrs. Cowen explained, ''and I didn't want to live with anything that represented my past.'' But because her apartment was near her children's schools, she decided to change it, and instead of moving, make it work for her family's new needs. Mrs. Cowen hired Kevin Walz, an interior designer, to undertake the project. The renovation was based on a complete redesign of her living space - to make the relatively small rooms double as entertaining and play spaces. Construction costs came to $62,000, not including furniture, lighting fixtures, carpeting and the slate floor.

Reagan faces decisions on policy in Southeast Asia A2 At least 16 killed in crash of U.S. Navy plane off Philippines A2 Study group sees need for greater European military effort A3 Greek quake kills 15 and seriously wounds 53 A3 Pope gets a warm welcome in Nagasaki A4 Queen Mother and Lady Diana have a tete-a-tete A5 Brezhnev aide denies Soviet arms go to Salvadoran rebels A8 Around the World A9 Group plans to protest disappearance of Guatemalan A13 Government/Politics Judge refuses to dismiss suit over F.B.I. informer A14 Wisconsin Democrats and Republicans upset by Court's move A17 Koch attacks group that criticized his anticrime proposals B11 Democrats demand more details on budget B15 General Around the Nation A14 Art Deco buildings at center of Miami Beach conflict A14 Well Fargo discloses details of bank fraud A15 Concern growing over Nassau's overcrowded jail B7 Consumer prices rise 0.8 percent in New York region B12 Chicago financier charged with fraud in search for Peking Man B16 Education/Welfare Ex-Congressman confident as new head of N.Y.U. B8 Features/Notes Notes on People B6 Man in the News: John Brademas, new N.Y.U. president B8 Obituaries Deszo Ernster, bass at the Met B16 The Home Section Home Cloning antiques: Museum reproductions C1 Restructuring an apartment to provide flexible living for three C1 Removing graffiti outside the house C3 Repairing damage to your garden C9 Bonsai lessons for the terrace C11 Home schooling, an issue for parents C1 Hers C2 Helpful Hardware C2 Home Beat C3 Home Improvement C4 F.D.A. is urged to limit salt in processed foods C5 Armani's new men's line adds casual and military elements C8 Design Notebook C10 Arts/Entertainment Nana Mouskouri, Greek pop singer, gives recital C12 Grammy awards presented at Radio City C13 City rejects Christo's "Gates" project for Central Park C15 Great social agonies are still attracting composers C16 First novels get record prices, but average advances decline C16 New-music concert by the American Composers Orchestra C16 "The Freak," a staging of the life of Edgar Cayce, mystic C17 Patrick Anderson's study of marijuana politics is reviewed C18 Judith Somogi named "first conductor" of Frankfurt Opera C18 Disney shows to appear on CBS in 1981-82 season C20 Sports Dave Anderson on John Ziegler's hockey law D20 Baruch and City College gain in tourney D20 Coghlan to skip mile and go for three-mile record D20 Baseball strike set for May 29 if no accord is reached D21 Rangers triumph over Sabres, 6-3 D21 B17 Bullets turn back Knicks, 120-105 D21 Flames rout Islanders, 11-4 D21 Seton Hall beats St. John's, 70-63 D22 News Analysis Bernard Gwertzman on Washington's El Salvador moves A6 Serge Schmemann views dispute on Rosedale school annex B1 Aljean Harmetz on the losers in Hollywood's poker game C15 Editorials/Letters/Op-Ed Editorials A18 Why only a popgun tax cut? Where allies can meet A primary's not a free-for-all Topics: diversions Letters A18 William Safire: the savings of El Salvador A19 Anthony Lewis: a tax-and-spend- ing cut of pie in the sky? A19 Jorge I. Dominguez: on Cuban- United States ties A19 Richard Scobey: the Peace Corps, at heart A19

''It is entirely appropriate to dispatch noncombat advisers to tell those people how to defend themselves against Cuba.'' - Howard H. Baker, Senate Majority Leader, on El Salvador. (A1:2.)

The Atlantic Richfield Company, the country's seventh-biggest oil concern, announced yesterday that it had agreed to sell The Observer, Britain's oldest Sunday newspaper, to the George Outram Company, a Glasgow publishing subsidiary of Lonrho Ltd., the British mining conglomerate, in a stock exchange valued at $14 million. The announcement represents the second recent ownership change on the troubled London newspaper scene, following Rupert Murdoch's purchase of The Times of London and its affiliated publications from the Thomson Organization. The Sunday Times is The Observer's chief rival.

Paul A. Volcker, chairman of the Federal Reserve Board, said today that the ''full magnitude'' of President Reagan's proposed budget cuts were essential to the anti-inflation fight. At the same time, the Fed chief cautioned that the effort to cut the inflation rate was unlikely to succeed easily, as President Reagan's economic advisers have suggested. ''I don't think their projections of inflation by themselves are unreasonable,'' said Mr. Volcker of the Reagan team. ''My concern is that the road from here to there may not be smooth, if I can put it rather conservatively.''

An Argentine airline jet, flying in clouds 1,500 feet lower than its assigned altitude, came close to crashing into a television mast atop a World Trade Center tower in downtown Manhattan last Friday at 10:05 P.M., according to Federal officials here. The Boeing 707 plane was about three to four miles south of the Trade Center -less than a minute and a half away -heading toward it about 200 feet below the top of the North Tower mast, when an automatic alarm buzzed in the Federal Aviation Administration's traffic control facility, the F.A.A. said. Simultaneously the controller responsible for guiding the plane recognized from data on his radar scope that the jetliner was flying too low, according to the agency account. Instantly the controller radioed the plane and ordered the crew to turn around and climb to 3,000 feet. That was the altitude the crew had been assigned to fly at, the F.A.A. said. The plane was later guided back into the regular traffic flow and landed safely at Kennedy International Airport.

Dan Marion is a mechanic, a shipping expert, a social worker, a fur buyer, a store manager, a banker, an engineer, a teacher, an accountant, a community leader, a janitor, a heating technician and a trilingual public relations officer. Mr. Marion has to be all these things because he runs an isolated Hudson's Bay store - a modern-day trading post for one of the oldest corporations in North America. ''It's a tough job,'' says the 35-year-old manager of the store, which rings up sales of about $1 million a year. ''But I don't think I could survive anywhere else.''

A new $16.6 million building for the Asia Society, under construction for nearly two years at Park Avenue and 70th Street, will open on April 14. The opening will touch off a two-and-a-halfmonth ''Celebration of Asia'' program, including concerts, films, symposiums and public affairs discussions. The eight-story structure will serve as headquarters for the 25-year-old Asia Society, a cultural and public affairs organization founded in 1956 by the late John D. Rockefeller 3d to educate Americans about Asian life and culture. It will contain galleries to house permanent holdings of Asian art, particularly the collection of some 300 objects given by Mr. and Mrs. Rockefeller in 1974, and thus bring another important museum facility to a neighborhood that at present has the Frick Collection, the Whitney Museum of American Art, the Metropolitan Museum of Art and numerous other institutions.

Jurors who last night convicted Jean S. Harris of murder recalled their deliberations today and spoke of reenactments, role playing, arguments, tears and three secret ballots before reaching a verdict on the eighth day. Five of the 12 jurors, speaking across kitchen tables, on livingroom couches and over the telephone, also indicated that Mrs. Harris's own testimony helped to convict her and they agreed for the most part that psychiatric testimony might have helped the defendant. Joel Aurnou, her lawyer, replied angrily to some of the comments, saying ''she told the truth.'' 'A Lot of Second-Guessing' As for the lack of psychiatric testimony, he said ''that's a lot of second-guessing.'' ''The jurors,'' he added, ''are saying 'it would have given us an excuse not to do what we did.' '' What they did - after nearly 48 hours of deliberations - was find the 57-year-old former school headmistress guilty of the most serious charge she faced, murder in the second degree.

-------------------------------------------------------------------- Elin McCoy writes frequently on childhood and education. By ELIN McCOY IT'S 9:30 on a weekday morning. Most children in Niantic, Conn., are in school, but not the three school-age daughters of Spencer and Eileen Trombly. The two older girls are upstairs doing independent study. The 10-year-old is in the kitchen working on math problems at a big blackboard. ''They all work between 9 and 1,'' explained Mrs. Trombly. ''The kids have their own nooks where they like to work, but they do science experiments in the kitchen and sometimes work at the big table we set up by the blackboard.''

Consumer prices rose last month by seventenths of 1 percent, the first time since August that inflation has increased at less than a double-digit annual rate, the Labor Department reported today. While the showing was considerably better than most economists expected, representing an annual increase in the inflation rate of 9.1 percent, none could be found who thought it represented more than a brief slowing in price increases. One reason the economists tempered their enthusiasm was that the department's survey had been made too early to register the big advances in the cost of gasoline and heating oil that followed the lifting of remaining price controls on Jan. 28. 'A Bit of an Aberration' ''There's no comfort'' in today's report, said Irwin L. Kellner, chief economist of the Manufacturers Hanover Trust Company. ''It does not reflect anything positive.''