A sound truck, an Econoline van with bullhorns angling from the roof, moved slowly through Rock Creek Park with Charlene Drew Jarvis riding shotgun, a microphone in hand, hunting voters in her campaign for mayor.

"There's one," Jarvis said, her amplified voice reverberating through the dignified quiet of an early afternoon in North Portal Estates, the manicured, neighborhood of substantial households where she lives and hopes to do well in next week's Democratic primary.

A man was caught exiting his car, trapped by the van in the street. "Can I count on you?" Jarvis asked. The man, stunned, said yes, and suddenly a campaign volunteer reached through a backseat window of the van and pinned him with a large plum-colored button that read "Jarvis for Mayor." Bullseye.

"I just came through to make sure my votes are secure," Jarvis sang into the microphone as the van rolled on. "Remember, polls are a game the media plays. You've got to decide who wins."

Never mind that she has raised less money than any of the other three Democratic candidates running for mayor or that the latest polls suggest that at best she is a spoiler, likely to get a mere 3 percent of Tuesday's Democratic vote.

Charlene Drew Jarvis is logging close to 300 miles a day as she rolls through the city in one of four similarly equipped vans, occasionally pounding the pavement to press the flesh and pass the word with a barrage of homespun political slogans such as, "Your vote has the might. Let me do the job right. Vote Jarvis for Mayor."

She is the first native Washingtonian to make a serious run for mayor since the advent of home rule in 1974.

Among others, there have been Sterling Tucker from Akron, Ohio, Walter Washington from Dawson, Ga., Marion Barry from Itta Bena, Miss., John Ray from Toms Creek, Ga., and Patricia Roberts Harris from Mattoon, Ill. Now there is Charlene Drew Jarvis, a daughter of the District of Columbia born in Freedmen's Hospital on Bryant Street NW on July 31, 1942.

Shouting into a microphone and stirring up votes from a sound truck is a world apart from the chandeliered parlors and gas-lit front lawns around Howard University and the communite academique of LeDroit Park where she attended Mott Elementary school.

True, she did move to Maryland for five years when her then-husband and former childhood sweetheart worked in Columbia. But in 1977, just as political opportunity was about to knock, she was back home in Washington.

Jarvis prides herself on being a "third-generation Washingtonian," a catch phrase connoting lineage to those in the city who are conscious of class and caste. She also has picked up more than a few political credits from being, as one Baptist preacher once affectionately described her, "Dr. Drew's daughter."

Dr. Drew--Charles R.--was a 1922 graduate of Dunbar High School here and is considered the father of the modern blood bank. It was he who, drawing on the laboratory experiments of others, perfected a way for separation of blood fluid (plasma) from the blood cells on a mass scale.

Drew's work, done early in World War II, permitted blood to be collected at centers all over the nation, shipped overseas and stored and used without regard to type and without the refrigeration that whole blood would have required. The achievement saved thousands of lives on the battlefield and made him a fixture in most modern-day black history lessons.

Charlene was 8 years old when her father died in an automobile accident in Alamance County, N.C., in 1950. His death left her with a desire to continue his work. Her older sister Bebe decided to study art after high school. Charlene chose science.

"Charlene has always been an extremely ambitious person," said her mother, Lenore Rollins Drew, who still lives here. "She was self-possessed and kept her own counsel even as a girl.

"After her father died, we were very fortunate because we didn't have to change our place of living. People provided for us because of who Dr. Drew was. I never had to go to work and therefore I could be a full-time mother and supervise her education. I was always home when she came home from school for lunch."

Jarvis speaks well of Lenore Drew's influence. "My mother was a selfless woman," she said. "She held us to a standard of excellence that was a given in those days. You were simply expected to achieve."

Unlike the children of many middle-class Washington blacks today, Charlene Drew attended public high school, Roosevelt at 13th and Upshur streets NW, at a time when segregation barriers in the city were just beginning to crumble.

Walking to school with Bebe along 13th Street NW, she noticed that a neighbor took the same route to work every day in a pink DeSoto convertible, but never stopped to give the girls a ride. That neighbor was Flaxie Pinkett. Charlene, as bold then as now, went to her house to ask why.

"I told her," Pinkett recalled recently, "that I left for work at 8 a.m. sharp and if she and her sister wanted a ride they would have to be on my porch when I left. Her sister could rarely make it out of bed on time, but Charlene never missed a day."

For four years, Charlene rode to school with Pinkett, keeping her up to date on the latest hit records and dances and gossiping about who, among black Washington's debutantes-to-be, was dating whom. "I felt like I was her big sister," Pinkett reminisced.

Indeed, the relationship went back even farther. It was the John R. Pinkett Realty company, Flaxie Pinkett's family business, that rented Dr. Drew, then chief surgeon at Freedmen's Hospital, and his wife, their first apartment on Sherman Avenue. They were living there when Charlene was born.

Fresh out of high school, Charlene married at age 18. In one of those rare events where a black person made the society pages of the local white newspapers, Charlene Drew, daughter of a life-saving surgeon, married W. Ernest Jarvis, a fifth-generation Washingtonian and heir to the House of Jarvis, one of the most prominent funeral homes in the city. Theirs was billed as a perfect union.

Marriage and the birth of two sons did not deter her career plans. Charlene Jarvis later graduated from Oberlin College, received a master's degree from Howard University and then a doctorate in neuropsychology from the University of Maryland.

For seven years she was on the staff of the National Institute of Mental Health in Bethesda and also served as chairman of its equal opportunity council.

She is now divorced, with two sons, Peter, 19, a recent graduate of Washington's School Without Walls, and Ernie, 20, an undergraduate at Howard.

During the last months of campaigning for mayor, Jarvis has been attempting to sell voters on the notion that the scientific method of problem solving can be effectively applied to politics.

Jarvis says she is convinced that her previous work, much of which involved dissecting monkey brains, gave her a key to unlocking the mysteries of the District bureaucracy.

"I have found that many of my skills are transferable," Jarvis said. "I have spent years studying brains and I feel the same things that make an effective scientist can make an effective public servant. I am very solution oriented."

Many native Washingtonians had long sought one of their own for mayor, complaining of the great influx of interlopers who had come to dominate city government after home rule. In earlier years, much of Washington's appointed black leadership was more homegrown.

But unity was elusive. Council Chairman Arrington Dixon considered a run for mayor and decided instead to seek reelection. And before Jarvis could launch her campaign, many in the hometown crowd had fallen in line behind Patricia Roberts Harris, a former presidential cabinet member and longtime member of the city's black establishment.

There was some talk that Jarvis was too new for the job. Her political career began when Dixon, then Ward 4's city councilman, vacated his seat to run for council chairman in 1978. Jarvis was the Ward 4 coordinator of the campaign. After he won, the new chairman and his then wife, Sharon Pratt Dixon, urged Jarvis to run in the special election to fill his seat. Jarvis did and won. She was reelected in 1980 to a four-year term.

Jarvis refused to play sequential politics by running first for an at-large council seat and then for chairman before trying for mayor.

"I had to move now," Jarvis explained recently, sipping from a can of Sego diet drink that she had pulled from her handbag for lunch as she rode in the campaign van. "There are people who say I'm moving too fast. But I ask: Too fast for what? Too fast for whom? I wanted to make a good effort to win now. Who knows what the next four years will hold?"

Now she is challenging not only the candidate backed by many of her old political allies, but also an old acquaintance, incumbent Marion Barry. "He's just not going to let me take power nicely," she said.

She has chosen as her campaign manager someone she considers equally tough--Woodrow Boggs Jr., a former assistant dean at Howard University Law School and a sports lawyer who ran Sterling Tucker's successful campaign for City Council chairman in 1974. "He's tough and they know it," Jarvis said of Boggs.

Boggs, psychiatrist James Collins of the Howard University School of Medicine and Jerome Shuman, a professor at the Howard University School of Law, are the people Jarvis says are playing the key roles in planning campaign strategy.

Boggs' assessment of Jarvis is nearly identical to her assessment of him. "She's the sweetest little girl," he says of her, quickly adding, "She's a determined woman, a high achiever who has earned her spurs."

Among those who disapprove of her campaign for mayor, however, is Flaxie Pinkett, her old chauffeur and long-time friend who helped her get elected to the council but now is playing an integral role in the Harris campaign.

"Whether running as a spoiler will help or hurt her politically, I can't say," Pinkett said recently. "When she told me that she was running for mayor, I just couldn't believe it.

"Charlene is an extremely ambitious person, which is all right, except that I think her move for mayor is premature," Pinkett said. "I don't think she's ready. Her background is in science, not economics or government."

Obviously, Jarvis disagrees. "I am being transformed from a scientist into a politician and that is scaring a lot of people," she said. "If I didn't make the change, there are people out there who would run over me."

Back on the road, her sound truck careened around the corner of Sycamore and Tulip streets NW where her brick and frame split-level home perches on a rolling lawn. Her youngest son, under her orders to mow the grass, had broken into a wrinkly-faced sweat as the van rolled up.

"There's another one for Jarvis," the loudspeaker crackled, "whether he likes it or not."