Public television has had dozens of eleventh hours. Now the bell tolls for it again. As representatives from 290 public TV stations convene here through Saturday for their annual membership meeting, they know they are facing Dust Bowl days, the worst financial crunch in public TV history.

As if to turn this story into even more of a cliffhanger, public TV has been bounced around again this week on Capitol Hill and by the White House. Sen. Ted Stevens (R-Alaska) introduced an amendment to restore $24.4 million in funding for fiscal 1984 that had been carved away by the House. But the appropriation for the Corporation for Public Broadcasting (CPB) was part of a catch-all "urgent supplemental" bill that the White House vetoed yesterday.

Public broadcasting was not mentioned in the veto message, however, and so a revised version of the urgent supplemental, with the public broadcasting appropriation intact, was expected to be approved quickly by both the Congress and the White House. That's the good news. The bad news is that even with Stevens' $24 million restored, federal funding for public broadcasting is still off 25 percent from fiscal '82 levels. Public broadcasting is going to have to tighten its belt to such an extent that its voice may change octaves.

And viewers of public television are going to see the results on their screens as early as this fall. Lawrence K. Grossman, president of the Public Broadcasting Service (PBS), is expected to announce at today's session at the Hyatt Crystal City Hotel in Arlington that starting in October PBS will cut back the number of hours it "feeds" programs to member stations. Saturday nights will go totally "dark," so that local stations will have to fill the time themselves. Feeds of repeat programs will be cut in half; if stations want to repeat shows, they will have to tape them themselves, at their expense.

While PBS stations will be repeating the popular six-part series "Tinker, Tailor, Soldier, Spy" next season, they won't be airing the sequel, "Smiley's People." It went to a higher bidder--commercial TV--and will be syndicated nationally to stations, including WDCA-TV in Washington, by Operation Prime Time. The new pay-cable service called The Entertainment Channel--available to only a tiny fraction of the viewing country, but generously financed with Rockefeller and RCA money--now gets first choice of programs from England's BBC that formerly turned up first on public TV.

Many local PBS stations are in financial straits so dire that they make previous crises look like bonanzas. KCET-TV in Los Angeles has laid off 77 employes since Jan. 1, reduced its own production to a virtual zero and is now renting out its production facilities; yesterday, Regis Philbin's cable health show was taped there. KCET even loses hefty sums on "The Dial," a program guide scheme by a four-station cooperative that was supposed to make, or at least save, money. At WNET in New York president John Jay Iselin recently announced that times were so tough he was voluntarily taking a $5,000 cut in his annual salary, to which a spokesman for another public TV station responded, "Yeah--down to a measly $100,000."

Some stations may have "dark" nights of their own soon, Grossman says, and there is the possibility that smaller stations, dependent on state funds that have also been severely cut, may go dark altogether.

(Washington's WETA-TV, however, is not in any kind of peril. In fact, it will finish the current fiscal year with a $150,000 surplus, according to station president Ward Chamberlin.)

At their meeting, PBS stations will be exploring ways to weather the storm. But when it comes to alternate financing, Grossman thinks most alternatives have already been tried. The private sector has not come roaring through with money to make up for Uncle Sam's fit of parsimony. Grossman says task force after task force has come to the conclusion that the federal government will have to continue to be the principal source of funding.

"This is going to be a very hard, tough, lean period," Grossman says. "We are going to try to make it as unnoticeable to the public as possible."

Grossman may also reveal, at today's session, plans for a PBS link with a major private satellite firm that would distribute PBS programs over a new pay-cable TV channel. Existing "cultural" cable networks like CBS Cable, Bravo and ARTS are all sinking fast into deficits, but Grossman thinks that's because they are advertiser-supported, not paid for by cable subscribers.

"It's a very risky, uncertain business," Grossman concedes. "But there's a definite market for it. There is a loyal, passionate but very small audience for a pay-cable service like this. We think we have a good opportunity in the field."

Grossman says the point of the service would be not to make money for PBS but to help finance new productions. The programs would be seen first on the pay-cable service and, later, free to viewers of PBS stations. The proposal to go forward with this plan, if Grossman actually introduces it, would have to be approved on Sunday by the PBS board. One public broadcaster calls the plan "dead," but Grossman says he thinks it still has possibilities. He will survey the "landscape of the new technologies" at this afternoon's session.

What will not be unveiled, Grossman says, is a dramatic plan for raising more money. "People are awakening to the reality that there's no magic," Grossman says glumly. "No life-saving new vaccine will be announced by me." Still, he thinks there is room for optimism, that "the pendulum is starting to swing back the other way." Public TV stations are getting better ratings than ever, arguably presenting more notable programming than ever, and during the most recent fund-raising drive took in more than $28 million, nearly a 9 percent increase over the previous drive.

Grossman does not blame the Reagan administration for public television's woes. "Budget cutting on non-defense areas is its prime target and I can understand that," he says, "but whether Carter or Reagan or what's-his-name, Anderson, had won, I think the mood of the country was that everybody in the public sector was going to be cut."

How much worse things will get for public TV is open to speculation, but for now, and despite public TV's history of panic and fiscal catastrophe, the crisis is real. They're crying wolf, but the wolf is right there at the door.