When Lt. Gen. Colin Powell, the president's national security adviser, stepped to the podium last night at the annual dinner of the Joint Center for Political Studies, he said he felt "right at home."

"I really was enjoying myself so much with the hospitality of the head table and just being away from the White House" -- he started out, pausing as he scanned the predominantly black head table. Laughter enveloped the room at the Grand Hyatt, where 1,600 people who had showed up to support the country's leading black think tank were eagerly awaiting Powell's first major address. "I feel right at home. I am almost reluctant to get into my prepared remarks," said Powell.

Recognizing that even though the center is a nonpartisan group, a significant number of the Reagan administration's critics would be present, Powell plunged ahead to outline the purposes of the National Security Counciland some of the administration's foreign policy priorities. Powell joined the NSC staff in the midst of intense scrutiny following the Iran-contra revelations. In the last 13 months under the leadership of first Frank Carlucci and now himself, he said, "On balance I think it is fair to say we have restored confidence and respect to the NSC system and the NSC process."

At one point, Powell mentioned "restoring defense spending," looked around for Rep. William Gray (D-Pa.) and ad-libbed, "He left -- good." Actually Gray had moved to the table closest to the door of the ballroom and was somberly listening to Powell's explanation of administration policy in Nicaragua, Angola, the Soviet Union and South Africa. "The achievement of democracy within Nicaragua is the key to a lasting peace in the region," said Powell.

"I disagree with much of those policies," Gray said later. "And I expect on February 4 when the vote is taken I will be fighting very strongly to stop all aid to the contras. I think providing aid at this time actually torpedoes peace, and instead of providing an insurance policy, it throws gasoline on the problem."

Gray said Powell's appointment as the first black to direct the National Security Council is "a major achievement for black people. But he is a messenger for his boss and I disagree with his boss. And I think we have to learn black folks are not always in agreement." During what Powell described as his "sampling" of the Reagan viewpoint, the audience was generally quiet but applauded when he mentioned support for the release from prison of South African leader Nelson Mandela.

The Joint Center's dinner and a concurrent four-day meeting of the National Policy Institute is one of the year's largest gatherings of black officials. The VIP reception was larger than some organizations' dinners. Former Virginia governor Charles Robb was in a huddle with former Atlanta mayor Maynard Jackson. Virginia Lt. Gov. L. Douglas Wilder, Los Angeles Mayor Tom Bradley, attorneys Vernon Jordan, Pauline Schneider and James Dyke, civil rights leaders John Jacob of the National Urban League, M. Carl Holman of the National Urban Coalition and Dorothy Height of the National Council of Negro Women, and D.C. School Superintendent Floretta McKenzie were present. Later, after the Powell speech, presidential candidate Jesse Jackson entered a side door and initially attracted little attention.

Last night, the center's largest dinner ever, raised $500,000 under the leadership of James D. Robinson III, chairman of the American Express Co., and Robert B. Washington, the managing partner of Laxalt, Washington, Perito & Dubuc.

The involvement of American Express prompted several jokes. Eddie Williams, president of the Joint Center, told the audience that the record fund-raising proved "the Joint Center did not leave home without Mr. American Express." When Mayor Marion Barry was welcoming the audience to Washington he looked at Robinson and said, "I have one or two in my pocket," drawing laughter from those who remembered that one of the city's credit cards was suspended last year for late payments.

In the season of Super Bowl countdown, there was a customary mention of the Redskins, but with a Barry-legend twist. Bradley, acting as the evening's emcee, said he was adjusting the order of speeches so Barry could "leave early for San Diego. He is going by wagon train."

Barry responded, "I'm really not going to take the wagon train. I have to work on my budget. But I am going to San Diego Thursday -- if it doesn't snow."

Acknowledging Barry's political embarrassment over the blizzard during the mayor's trip to last year's non-Redskins Super Bowl, Bradley promised, "If it snows, we've got a standby plane to get you home."