A Los Angeles man who was named 1983 Hispanic Businessman of the Year admitted in federal court in Alexandria yesterday that he conspired to bribe public officials in a scheme to reap millions in profits from Navy defense communications contracts.

Manuel M. Caldera, 59, who also received minor appointments from the Ford and Carter administrations, pleaded guilty to conspiracy to defraud the government and bribery of a public official. Caldera is one of the most prominent businessmen targeted by the ongoing Ill Wind investigation into Pentagon procurement fraud, which has now prosecuted 35 individuals and four corporations.

Former chairman of the board of Amex Systems Inc. in Los Angeles, Caldera faces a maximum possible sentence of 7 years in prison and fines of up to $500,000. U.S. District Judge Claude M. Hilton set sentencing for Nov. 30.

Caldera, whose company thrived on sole-source defense contracts that were set aside for minority-owned businesses, began with a handful of employees and $7,000 in revenues in 1971. Twelve years later, Caldera employed over 700 people, posted revenues in excess of $62 million and became a leader in the Hispanic business community.

At a 1983 meeting of the United States Hispanic Chamber of Commerce, President Reagan hailed Caldera as businessman of the year and applauded him for his contributions to a Mexican orphange and to college scholarships for Hispanic students studying science and engineering.

"You prove that with freedom of enterprise come values that make America more than a rich country -- they make us a good country," Reagan said, addressing Caldera and other Hispanic businessmen.

Jose F. Nino, president of the national Hispanic Chamber of Commerce, said yesterday that Caldera's plea was a grave disappointment, but added that Caldera's guilt in no way reflects on the general Hispanic business community.

"I would like to see it as one man with his own problems," Nino said. "Our community is striving constantly to move forward, and we have to keep working harder because of the obstacles we face every day."

Caldera, who sold his company in 1984 to Allied Corp. for $45 million, paid over $28,000 to two Navy procurement officials to help Amex win or extend $50 million worth of defense contracts from 1977 to 1984, according to court papers.

Federal prosecutors said the Navy officials modified several contracts for shipboard transit receivers and satellite communications systems so that Amex would double and sometimes triple its revenue on the projects.

But Caldera said in documents filed in the case by his attorney that his company was held hostage by Navy officials who threatened to shut off the flow of contracts to Amex if Caldera refused to give them money. Caldera said he "received the clear impression that unless he made payments to {one official}, Amex would not receive approvals to which it was entitled."

Caldera also said an official demanded money because his mother was sick and needed care in a nursing home. Caldera concluded that his mistake was in "making payments rather than reporting the individuals."

U.S. Attorney Henry E. Hudson, whose Alexandria office is leading the Ill Wind investigation, said Caldera was clearly the leading force in the conspiracy. "It seems inconceivable that a person with the political influence of a Mr. Caldera could possibly be intimidated by a mid-level Navy employee," Hudson said.