To hear Ralph Waldo Emerson, chairman of the board of Emersons Ltd. restaurant chain, tell it, he is just one of the 30 members of D.C., mayoral candidate Sterling Tucker's finance committee. Tucker probably wishes he had 29 more like Emerson.

With about 50 telephone calls to friends, Emerson said he has been able to raise $4,950, "give or take a hundred or two," to help Tucker's bid to win the Sept. 12 Democratic primary.

"I just say, "Look, here's this super guy. I know he's going to win. He'll make a good mayor."

And then comes the irrresistible pitch, in Emerson's Tennessee drawl, to help an old friend.

"Look, I got on this fundraising committee. Don't let me get egg on my face. Send me some money."

Twenty people have done so, and Emerson said theother 30 will be receiving return calls.

"You really have to bug people, harass 'em," Emerson said. "You mention the limit is $1,000. And the say, 'A thousand dollars?!' and ask if $100 is okay. And you say 'sure.'"

Business executives such as Emerson, a former Tennessee gubernatorial candidate and a dircet descendant of the 19th century poet of the same name, are helping Ciy Council Chairman Tucker tap the pockets of well-to-do corporate officials, lawyers and real estate interests for donations to run the campaign.

Tucker has collected about $75,000, almost hald in the form of $1,000 contributions, the maximum allowed for each donor in the city election. Many such donations have come from the business community.

In contrast, Marion Barry, one of Tucker's chief opponents, has raised $57,000, mostly in small donations, often of $50 or less.

The third major candidate expected on the primary ballet is Mayor Walte E. Washington, who has not announced for reflection but is expected to within the next week. City politicians assume that he like Tucker, will be able to raise large sums for his campaign from the business community.

The art of political fundraising is a relatively new phenomenon for city residents, even though nationally oriented political fundraisers have been held here for years.

Mayor Washington raised about $200,000 four years ago when he became the city's first elected mayor under the limited home rule granted by Congress, although some business people noted a reluctance to contribute to city political candidates when politics was so new to the city.

TRhat reticence still exists somewhat gradually is eroding, according to several fundraisers this year.

The fundraiser's chief asset - here as elsewhere - seems to be a belief in the product (the candidate) and the instince of knowing when to make The Pitch.

Emerson seems to qualify on both counts. "I met Sterling six, seven years ago," he recalled. "I find him to be usually bright for a politician, and I think he cares. He's experienced. Toss in a little honesty, and you've got an unusual man."

So, when Emerson was chatting recently with a friend who runs an automobile franchise in Nashville, he mentioned that he is supporting Tucker in the mayor's race.

"He sent me $100 and he never laid eyes on Sterling," Emerson said.

Emerson said each of the 30 Tucker finance committee members is trying to raise $10,000, which would give Tucker $300,000, a substantial campaign treasury. Campaign officials also said that some fundraisers are trying to raise specific amounts within certain professions in the city.

Thornton W. Owen, chairman of the board of Perpetual Federal Savings and Loan Association, noted in one campaign fundraising letter that the Tucker campaign was "looking to raise approximately $20,000 from the S & L's and a slightly greater amount from the banks."

Owen noted that "it is probably easier to raise funds by asking various individuals for smaller amounts totaling not less than $1,000 per (S & L) association. I will see that eash association gets proper recognition."

Another Tucker fundraiser is William B. Fitzgerald, president of Independence Federal Savings and Loan Association of Washington and a successful black businessman.

Fitzgerald said that he has sent 25 to 30 letters to friends on Tucker's behalf and that he promotes Tucker's candidacy when the occasion is right. "If politics is the topic the conversation. You don't bring it up if the talk is about the Bullets.

"My simple pitch if I bump into someone in a restaurant is that I'm supporting Sterling. I'm not a pusher. I always find it particularly difficult to ask anyone for something," he said.

While Barry also has a corps of fundraisers working for him, they have not - so far - reaped more than a dozen $1,000 contributions.

"It's not because we haven't tried," Barry campaign manager Ivanhoe Donaldson said. He said the simple reason is that "the mayor and Sterling Tucker are supported by the leadership of the (Metropolitan Washington) Board of Trade. Marion's not part of the club.

"I don't have any bankers making calls for me," Donaldson said.

If the Barry campaign hears of a prospective donor, one of his workers or sometimes Barry himself calls the person to request the donation.

"We'll have far more contributors all along" than Tucker or Washington, Donaldson said.

That is not to say, however, that Barry has written off the prospect of donations from larger contributors. He has scheduled a $250-a-person business executive's luncheon later this month and said he hopes to have at least 50 people there.

Barry said that after the lunch, if he runs into someone who was invited but did not appear, he will ask them for a donation anyway.