"IT IS NOW 11:15," boomed political satirist Mark Russell, taking the stage after four hours of reception, dinner and speeches in behalf of PBS, the Public Broadcasting System. "DO YOU KNOW WHERE FRANK MANKIEWICZ IS?"

The 800 guests hooted and applauded at this dig at the man who recently left National Public Radio in the midst of serious budget problems. The crowd in the Crystal City Hyatt Regency ballroom included volunteers, board members and managers of PBS stations, which, like NPR, get much of their funding from the Corporation for Public Broadcasting.

They had just heard such stars as Zoe Caldwell, Ossie Davis, Ruby Dee, Roberta Peters, LeVar Burton, Fred Rogers (Mr. Rogers) and ABC News and Sports President Roone Arledge extol the splendors of public television. PBS billed the evening as its tribute to Congress, which allocated $137 million to CPB in the current fiscal year.

"Before we serve breakfast," said Russell, "this has been a wonderful evening. God, it's past Fred Rogers' bedtime. This is a salute to Congress--so if there's any congressman left in here, wake him up and salute him."

Despite the jokes and good sentiments, the crowd couldn't escape the shadow of NPR's problems. "It's a sad time," said Lawrence Grossman, PBS president. "Usually when Congress is talking about our appropriation, they come up with some incident of frontal nudity. This year they have NPR."

But CPB President Ed Pfister and CPB Chairman Sharon P. Rockefeller vowed to try not to let funding problems spill over to PBS. "We're not going to penalize public television for the fact that public radio has stumbled," said Pfister.

Earlier in the day, CPB pledged to help NPR solve its financial problems, which stem from a projected $9.1 million deficit for fiscal 1983. Some NPR officials believe the network needs $6 million to $10 million in the next month or so to guarantee its future.

But PBS had certainly done its share to keep the night and the mood upbeat. Before dinner, there was a lavish spread of hors d'oeuvres, including shrimp and oysters Rockefeller.

Along with dessert came stunning endorsements of PBS. A sampling:

From Zoe Caldwell: "I have two sons . . . and because I want them to grow into two terrific human beings I saturate their lives with sensuality--the sensuality of beauty, the sensuality of pain, the sensuality of taste . . . the sensuality of sexuality . . . and at some point in the day PBS supplies all of those things."

From Mason Adams, who played the managing editor Charlie Hume on "Lou Grant": "For me, PBS is the best and the brightest . . . it is what I watch. When people used to come up to me to say they only watched PBS and 'Lou Grant,' I knew we'd arrived. I also knew we'd get canceled."

From Arledge (whose ABC News has contributed funds to PBS for a series on Vietnam this fall): "When you look at someone like me who represents commercial television--although I must say I watch you more than I watch commercial television--you think we're the competitor. We're not competitors. We have just as large a responsibility to support PBS."

The appearance of the ABC honcho was not lost on Mark Russell. "The question on everyone's mind as we walked in here tonight was, 'What the hell is Roone Arledge doing here tonight?' " said Russell. "You do all know Roone Arledge, don't you? He's Frank Mankiewicz with a big budget." The crowd laughed.