Goal: self-sufficiency; Public radio triples its programming

National Public Radio is quietly setting its dial for self-sufficiency.

Just after midnight, Jan. 3 - with nary a bleating trumpet or all-points bulletin - the noncommercial network will triple the amount of programming poured out through its satellite system.

The beefed-up broadcasting is a direct result of NPR's efforts to trim local station costs and launch moneymaking businesses, such as a computer data transmission service and a national paging system.

To accommodate the proposed business ventures, stations will need to be on the air 24 hours a day. Currently, less than 20 percent of the network's 276 member stations boast an around-the-clock schedule.

''This new programming will allow the stations to expand their service into the overnight hours without adding significantly to their costs,'' says Tom Warnock, executive vice-president of NPR. At the same time, the additional 220 hours a week of music and news will allow the network to rake in more money from corporate underwriting.

Dubbed ''NPR Plus,'' the new programming includes a 24-hour, 7-day-a-week classical music service and a 6-night-a-week jazz program. The network is also adding a half-hour afternoon news program - ''NPR Dateline'' - as well as hourly news updates throughout the day.

Stations have the option of paying $5,000 a year for the expanded programming - picking and choosing what they want from the smorgasbord of NPR offerings - or sticking with NPR basics, such as news programs ''All Things Considered'' and ''Morning Edition.''

According to NPR president Frank Mankiewicz, the new programming is the first step in the network's five-year plan for financial independence. This year, less than $30 million of public broadcasting's federal funding went to radio - $12 million to NPR in Washington, the rest spread among the local stations and other related activities.

By 1988, Mr. Mankiewicz says he's aiming to free NPR's central operations from federal support - with roughly half its budget coming from business activities and the other half coming from grants and contributions from the private sector.

NPR businesses that involve commercial use of the network's satellite system, such as computer data transmission, are currently being examined by the Federal Communications Commission (FCC). Decisions on whether or not to permit such activity are expected early next year.

''The economy remains a tough problem for us,'' says Mankiewicz. At the same time, NPR just finished a year of fund raising that ''exceeded all expectations.''

The network has raised $3.7 million from private corporations and foundations since announcing its independence campaign in November. The goal for the year had been pegged at $3 million.

Part of the bounty is due to the network's ability to attract corporate underwriters - companies that buy ''shares'' in NPR programs in return for on-air mentions. Last year, the FCC made underwriting a more attractive proposition when it eased the rules to allow 10-word descriptions of the sponsoring companies.

The growth of NPR's listening audience is also good for business. Between 1980 and 1982, the number of listeners increased almost 60 percent, from 5 million to nearly 8 million. Most of that increase, however, came during the 1980-81 period.

So far, more than 100 stations have signed up for the expanded service. One early recruit, WKGC-FM in Panama City, Fla., will save more than enough to pay for the additional programming.

''We're now paying a syndicator $9,000 a year for 30 hours of classical music a week,'' says station manager Charlie Wooten. ''When we get this, we'll have 24 hours a day for $5,000, plus all the rest.'' The station will add overnight broadcasts sometime in March or June, Mr. Wooten says, ''whenever the data transmissions begin.''

Even stations that already have around-the-clock schedules plan to use the service to shave operating expenses. Michael Nitka, program director at WAMU-FM in Washington, D.C., says he'll save more than $5,000 a year in his news department alone. The savings will come from shifting full-time staff to do some of the work that had been done by part-timers.

In addition to saving money, NPR executives contend the new offerings will help boost the quality of programming at the local level.

The typical NPR station, says NPR vice-president Warnock, devotes half its broadcast day to ''needle drop'' programming - locally produced shows with disc jockeys playing records.

''If we select programming from the best stations and independent producers, '' says Warnock, ''we can put together a package of programming as good as or better than the stations could produce themselves.'' This, in turn, will free up staffs for more creative local programming.

Station executives, for their part, say they'll try to retain a ''hometown'' sound by plugging local news and weather into the pre-packaged programming received via satellite.

''Even though it's not coming off our own turntables, the listener will perceive it as something coming from the local radio station,'' says WKGC's Mr. Wooten.