Lucille Ball was always willing to entertain the troops and to visit hospitals too.

'I Love Lucy'' had its premiere on Oct. 15, 1951, and within a few months millions of Americans tuned in every Monday evening to watch the antics of the Ricardos and their best friends, Fred and Ethel Mertz (William Frawley and Vivian Vance). ''I Love Lucy'' was one of the first shows to be filmed rather than performed live, making it possible to have a high-quality print of each episode for rebroadcast, compared with the poor quality of live-show kinescopes. The change eventually led to a shift of television production from New York to Hollywood. The show was the first to be filmed before an audience, and crew members used three cameras at once to permit motion-picture-type editing. The series won more than 200 awards, including five Emmys. Jack Gould of The Times offered this analysis: ''The extraordinary discipline and intuitive understanding of farce gives 'I Love Lucy' its engaging lilt and lift. Only after a firm foundation of credibility has been established is the element of absdurdity introduced. It is in the smooth transition from sense to nonsense that 'I Love Lucy' imparts both a warmth and a reality to the slapstick romp that comes as the climax.'' Miss Ball's superb timing, Mr. Gould wrote, makes her ''the distaff equivalent of Jack Benny,'' her professional idol. A Fortune in Rerun Rights Mr. Arnaz made a fortune for the couple by obtaining rerun rights for the series. He later sold the rights to CBS, allowing the couple's production company, Desilu, to buy a studio, the former RKO lot where Miss Ball's film career had languished and where they had met in 1940 while appearing together in ''Too Many Girls.'' Despite the continuing popularity of ''I Love Lucy,'' the couple sought a less demanding schedule and ended the series in 1957 after making 179 episodes. The format persisted, however, for three more years through a series of hourlong, high-budget, around-the-world specials called ''The Luci-Desi Comedy Hour.'' Their collaboration ended with their divorce in 1960. Mr. Arnaz died in 1986. Two years after their divorce, Miss Ball revived ''Lucy,'' playing a widow in ''The Lucy Show'' for 156 episodes until 1968, then did ''Here's Lucy'' for 144 episodes from 1968 to 1974. In these two series she was joined by her two children, her longtime friend Vivian Vance and Gale Gordon, who succeeded Mr. Arnaz as her masculine foil. In shaping situation comedies, Miss Ball consistently sought superior writers, followed their advice, gave them unstinting credit and paid close attention to production details. In later movies, she co-starred with Bob Hope in two comedies, ''The Facts of Life'' (1961) and ''Critic's Choice'' (1963), and appeared with Henry Fonda in ''Yours, Mine and Ours,'' a 1968 farce about a couple with nearly a score of children. In 1974 she starred in a film version of the stage hit ''Mame.''