To Rep. Ronald V. Dellums (D-Calif.), the House passage Wednesday of his stringent economic sanctions against South Africa was "a shot heard 'round the world." But he also views it as personal "exoneration" from the judgment that he is a moral gadfly and maverick who is out of the mainstream of power in the House.

The House astonished itself and many observers by passing Dellums' bill calling for a trade embargo and complete divestment by U.S. companies and citizens of their holdings in South Africa. It was the first time that divestment legislation has been passed by either house, and Dellums' version was far more stringent than the bill most observers expected to be passed.

In an interview yesterday, Dellums described the action as a major blow to apartheid that can't be undone or turned back. He also views it as a refutation of the belief of many -- which is "personally painful" to him -- that he is just another flaky politician from Berkeley.

"'Berserkely,' a lot of them call it," he said, smiling ruefully.

"Yesterday's action was the shot heard 'round the world, that was heard in Pretoria," he continued. "We haven't simply altered the debate on apartheid, we've changed the environment. Whatever the dynamics of that moment, its effect can't be changed.

"Whatever comes out of the Senate and conference has to be stronger. We've opened new possibilities because we've moved the fear barrier back. We politicians live with a multiplicity of fears."

This view was shared on both sides of the aisle in the House.

"Yesterday, the House went to Ron Dellums; Ron Dellums didn't go to the House," said Rep. Jim Leach (R-Iowa). "Bill Gray went to the House, but the House went to Dellums."

Leach was referring to a more moderate sanctions bill sponsored by Rep. William H. Gray III (D-Pa.), chairman of the House Budget Committee and one of the House's most influential insiders. It was expected to pass but was never voted on because of the surprise call-up and passage of Dellums' bill, which was the designated substitute for Gray's.

Passage of his bill was a personal milestone for Dellums, 50, a veteran of nearly 16 years in the House.

"This is the highest point of my political life, the most significant and personally rewarding," he said. "It's been a long journey to this moment."

His next most satisfying moment was his presentation of the alternate military budget in 1982, which proposed reducing spending by more than $50 billion and canceling several nuclear missile programs. It got only 55 votes, about a third from the Black Caucus.

In many ways, Dellums is a paradox.

He is still the outspoken liberal he has always been, but his colleagues now see him as one of the most gentlemanly, considerate, even courtly members on Capitol Hill. They also value him as a "moral force for reordering priorities," in Leach's words, but think he's "too liberal to be in the mainstream."

Dellums, however, finds that the role of moral-outsider-gadfly leaves a lot to be desired.

"I came here not to project my personality but to project ideas, to lift the level of debate above rancor and personal attack," he said. "We're talking war and peace, life and death, man, and if you carry controversial ideas in a controversial personality, how can you ever get anything done?"

The problem, he contends, is that he came to Congress during the counterculture revolution of the 1960s and the anti-Vietnam war protest and became the personification of Berkeley and all it symbolizes.

"My humanity got lost in the process," he said. "It has been personally painful to be considered just a gadfly, a maverick, a strong speaker, but outside the mainstream of power. What yesterday was about is that people have to see me in a serious way. This has been an exonerating factor."

He denies that he has just been an "off-the-wall voice."

"I introduced the first divestment bill 16 years ago," he recalled. "Did I come to the country or did the country come to me?"

When he first came to the Congress, Dellums seemed to be challenging its very legitimacy and that of the leadership, holding unofficial "hearings" on Vietnam war atrocities and racism in the military. Over the years, however, he's mellowed.

His seniority entitled him in 1983 to become chairman of the military construction subcommittee, and he surprised his colleagues by his considerate dealings with them and his skill at managing legislation.

Dellums said that on Wednesday, he could sense momentum for his bill building during the day.

"Members, including Republicans, would come up to me and say, 'Ron, I wasn't with you last year but I am this time.' I could also tell from the spectrum of people who were asking for time to speak on its behalf, including a greater number of Republicans. I knew we were gaining but not necessarily that we'd win."

As floor manager of the bill, Dellums had 30 minutes of debate time to mete out to his supporters.

"I don't like to give a colleague just a minute or 30 seconds to speak," he said. "But there were so many I had no choice. When Rep. Charles E. Bennett D-Fla. got up to speak, I had to fight back tears because I knew where he was coming from."

After the voice vote by which the measure passed, Dellums expected its opponents to call for a recorded vote.

"I sure wasn't going to ask for it but I was astonished that no one else did," he said. "I guess it was because they realized that if they did they'd have to account for their votes."

A staff aide speculated that conservatives who oppose sanctions wanted a bill so tough that the Republican-controlled Senate would balk at it. He also contended that the House leadership didn't want to chance defeating Dellums' measure because that would look like the House was backing down.

"They blundered into principle," he said.