Orlando, Fla, Nov. 17 -- Declaring that “I am not a crook,” President Nixon vigorously defended his record in the Watergate case tonight and said he had never profited from his public service.

“I have earned every cent. And in all of my years of public life I have never obstructed justice,” Mr. Nixon said.

“People have got to know whether or not their President is a crook. Well, I’m not a crook. I’ve earned everything I’ve got.”

In an hour-long televised question-and-answer session with 400 Associated Press managing editors, Mr. Nixon was tense and sometimes misspoke. But he maintained his innocence in the Watergate case and promised to supply more details on his personal finances and more evidence from tapes and presidential documents.

The President was loquacious in his answers and at the end solicited a question on the charges that the administration raised milk support prices in exchange for campaign contributions from the milk lobby.

Denying the charge, the President said Democrats led the fight in the House and Senate for higher support prices and pointed a gun at his head requiring him to boost support prices.

The President acknowledged that he had “made a mistake” in not more closely supervising campaign activities. In a question on what he may do after he leaves office, he quipped that it depended on when he left.

Then, becoming serious, he said that he would write but not speak, practice law or serve on boards of directors. One thing he will do is work for new rules of campaign procedures. He said he did not want to be remembered as a President who did many things but let his own campaign get out of hand.

Mr. Nixon acknowledged under questioning that he paid only nominal income taxes in 1970 and 1971 but he did not give figures. He also said that his brother Donald’s phone was tapped for unexplained security reasons.

Discussing energy conservation, Mr. Nixon drew laughter when he said that he had made a saving by refusing to allow a back-up aircraft to follow him on this trip.

“If this one goes down,” he said in reference to his Air Force plane, “they don’t have to impeach.”

While the President was nervous, he was not floored by any of the questions but answered them much as he does in any press conference.

He flew here tonight from his Key Biscayne, Fla., home for the much-heralded question-and-answer period. He was well prepared, remembering dates and times when he held key meetings with various aides on Watergate matters.

Summing up, he declared that the White House tape recordings would prove that he had no prior knowledge of the Watergate break-in, that he never offered executive clemency for the Watergate burglars, and in fact turned it down when it was suggested, and had no knowledge until March 21, 1973, of proposals that blackmail money be paid a convicted Watergate conspirator.

Regarding the June 20, 1972, brief telephone conversation with former Attorney General John N. Mitchell, Mr. Nixon said no tape was made because the call was from the family quarters in the White House. He said he called to cheer up Mitchell because Mitchell was chagrined because he had not properly controlled those under him -- in the re-election campaign, which he once headed, and the burglary was embarrassing the administration.

Mr. Nixon said he was very greatly disappointed that the tapes of the Mitchell conversation and the April 15, 1973, conversation with former counsel John W. Dean III did not exist.

He was told first on Sept. 29 or 30 this year that the tapes in question might not exist, the President said. After a search, it was determined on Oct. 26 that they did not exist, he said.

He said he dictated a report on the Mitchell conversation, which does exist, and has notes on the Dean conversation which he has turned over to U.S. District Court Judge John J. Sirica.

His own taping system was “a little Sony with lapel mikes” at his desk, and it was not as good as the system President Johnson had, Mr. Nixon said.

But the tapes can be heard, he said, and will prove that he was not involved in the Watergate cover-up, he insisted.

When he was asked about a report in the Providence Journal that he paid $702 in income taxes in 1970 and $878 in 1971, Mr. Nixon congratulated the paper on its sources of information but did not confirm or deny the figures, although he said they were nominal. He said he paid $79,000 in income taxes in 1969.

After Mr. Nixon entered office, former President Johnson told him he had given his presidential papers and that he, Mr. Nixon, could give his vice-presidential papers to the government for a tax deduction.

The Internal Revenue Service appraised the papers at $500,000 and the people who prepared his returns took that deduction, the President said.

“I can only say that what we were told was the right thing to do and of course what President Johnson has done before. And that doesn’t prove certainly that it was wrong because he had done exactly what the law required. Since 1969 of course I should point out presidents can’t do that.”

Mr. Nixon said the government could give him back the papers any time and he could make more than $500,00 by publishing them.

“I am the first President since Harry Truman who hasn’t owned any stock” since taking office, Mr. Nixon said.

When he left office as Vice President in 1961 his net worth was $47,000, he said. “In the next eight years, I made a lot of money,” he said.

Mr. Nixon said he made $250,000 from his book, “Six Crises,” and earned between $100,000 and $250,000 a year practicing law.

In 1968, he said, he sold all his stock for about $300,000, his new New York condominium apartment for $300,000, and received $100,000 due him from his law firm.

“I made my mistakes,” he said, “but in all of my years of public life I have never profited from public service.”

When asked whether Donald Nixon’s telephone was tapped by the Secret Service, the President said the Secret Service “did maintain a surveillance. They did so for security reasons, and I will not go beyond that. They were very good reasons, and my brother was aware of it.”

The President did not use the phrase “national security,” but only “security.” When questioned further he said the surveillance “involved not what he was doing (but) others who were trying to get him, perhaps to use improper influence and support might be doing, and particularly anybody who might be in a foreign country.”

[In September, the Washington Post quoted reliable sources as saying Mr. Nixon ordered his brother’s phone tapped because he feared that his brother’s various financial activities might embarrass the administration.]

Asked if his brother was aware of the surveillance, he said. “He was aware during the fact, because he asked about it, and he was told about it. And he approved of it. He knew why it was done.”

The questioning continued to focus on Watergate almost for the entire hour even though the President seemed pleased when he got a few questions on other subjects.

When asked whether he still thought former aides John D. Ehrlichman and H.R. (Bob) Haldeman were fine public servants, as he once characterized them, Mr. Nixon called them “dedicated, fine public servants, and it is my belief, based on what I know now, that when these proceedings are completed that they will come out all right.”

But he said it “probably doesn’t make any difference whether the grand jury indicts them or not, because unfortunately they have already been convicted in the minds of millions of Americans by what happened before the Senate (Watergate) committee.”

It was in this context that the President seriously misspoke himself, saying, “I hold that both men and others who have been charged are guilty until we have evidence that they are not guilty.”

His press secretary arranged for a subsequent questioner to make a correction.

The President recalled that Assistant Attorney General Henry Petersen said six months ago that the Watergate cases were 90 per cent completed. Yet former Special Prosecutor Archibald Cox never brought the cases to conclusion, Mr. Nixon said. He urged that the cases be brought to trial as quickly as possible to clear those who are innocent and fix the blame on those who are guilty.

The President said he did not know until March 17, 1973, that the office of Daniel Ellsberg’s psychiatrist had been broken into by White House “plumbers.”

“I personally thought it was a stupid thing to do, apart from being an illegal thing to do,” he said.

The President remarked toward the end of his scheduled hour that the editors had not raised some of the subjects that he had obviously expected, including milk prices and the International Telephone and Telegraph Corp. case.

He said he would raise these questions himself and hoped that he could answer them “through the medium of a television conference like this.”

He went on to say he would send to the “editors of the nation’s newspapers, all 10,000 of them, the facts. I trust that you will use them . . . but if you feel you need more information, write to me and I will give it to you.”