The NBC "N" is going the way of new, improved Coke. Out the window. In the months ahead, NBC will be phasing out the "N" logo it has used since 1976 and will introduce a new corporate symbol involving a redesigned NBC peacock and all three letters of the network's name.

Company officials hope to retire the "N," known around the network as "The Big N," by next June, when the new logo will begin to appear.

"The Big N" was born in a brouhaha nine years ago. Soon after its unveiling, NBC was informed that it had violated the copyright of the Nebraska Educational Television Network, which had unleashed its own "N" on the world eight months earlier. NBC spent about $750,000 to develop its "N" and Nebraska ETV spent less than $100 on its but, n-barrassingly enough for NBC, the two symbols were almost identical.

NBC's costs went up still further. To avoid litigation over ownership of the suddenly controversial "N," NBC gave Nebraska ETV $500,000 in new equipment and $25,000 to develop a new logo, in return for exclusive domain over "The Big N." Now after all that fuss, "N's" end is near.

NBC executive vice president M.S. Rukeyser Jr., vacationing in the south of France, said yesterday from an expensive hotel that the demise of the "N" had been planned for years and that former NBC chairman Fred Silverman ordered up something called "The Proud N" as a transitional logo. "The Proud N" consists of "The Big N" with a tiny peacock embedded in it.

Rukeyser conceded that "The Proud N" was something of a flop.

"The peacock is round and sort of playful, while the 'N' is rigid and geometric, and they don't work together," Rukeyser said. The famous designer Ivan Chermayeff is putting the finishing touches on the new peacock, which will be "simplified" so that it will look better in print, Rukeyser said. The old one tended to turn into a seashell when reduced in size to fit on company stationery.

"Instead of 11 feathers, the new peacock has six," Rukeyser explained. "Each feather will be a different color and each color will be a signature for a part of NBC." Rukeyser said the timing is right for a change of corporate face. "Since the company's doing better, it seems a good idea," he said. "Everyone thought it would be a little insane when we were in the dumps to start worrying about our logo."

Rukeyser declined to authorize release of the new peacock's picture on the grounds that NBC affiliates should see it before it is revealed to the outside world. Then he went back to his bouillabaisse.

Bemused by NBC's adventures is Jack McBride, general manager of Nebraska ETV now and when the "N" row erupted. "I guess this is just the final step in the transition," he observed yesterday, in Washington for meetings about new technology in public television.

McBride said the arrangement with NBC had "worked out quite well," although four of the color cameras acquired in the deal have since been retired. A new Nebraska ETV logo, a lower-case "n" that suggests the shape of the state, was devised and is still being used, McBride said. Asked if he would like to grab that big "N" once it is available, he said, "I doubt seriously we would be interested in returning to that. Actually we, in a very democratic process, had developed in-house three different possibilities for a new logo at the time, and the one NBC later took was the winner by a very narrow margin."

It will cost NBC up to $6 million to replace all the old logos throughout the company with new ones, an NBC spokesman estimated. Its formal introduction will be tied to the arrival of the 1986 fall TV season, he said. The year 1986 marks the 60th anniversary of the National Broadcasting Co..

Apparently there will be few tears wept at the passing of the "N." It seems to have been no better loved than "the snake," the ugly NBC logo that preceded it and in which the "B" was part of the "N" and the "C" curled underneath them. Of the lame-duck "N," an NBC spokesman said yesterday: "It really didn't tell the story. And it was sort of cold."

It'll actually get colder. For "The Big N," it's The Big Chill.