Network television news lost another one of its grandees yesterday with the announcement that David Brinkley is quitting NBC News after a 38-year career with the network.

Brinkley, 61, said yesterday that "the date for my retirement has not really been settled yet -- we still have to sign a piece of paper," but the network announcement said it would be sometime next month.

Brinkley stressed yesterday that he's "not quitting work."

"I just wanted a change," he said, noting that he had "already received a dozen phone calls regarding possible jobs."

Although the official announcement from the network was couched in the most friendly terms, Brinkley suggested to a reporter that he was frustrated in his current assignment as anchor and managing editor of "NBC Magazine With David Brinkley," which is scheduled to return for a second season Sept. 11.

"My complaint is that I'm not now able to do what I think I am good at -- to do the news in Washington and cover politics -- what I've done since I was 20 years old," Brinkley said.

"As NBC is presently structured, there's no way for me to do it. It's all locked up. But I'm not bitter."

His departure from NBC follows by five months the departure of Walter Cronkite from his daily stint as anchor for CBS Evening News.

For 15 years, from 1956 until 1970, when Brinkley's co-anchor Chet Huntley retired, the nightly "Huntley-Brinkley Report" on NBC dominated the network news field, and it was only with the breakup of that powerful team that Cronkite and the CBS Evening News gradually assumed the leadership in the field that it still maintains, although by a narrow margin.

Brinkley's distinctive delivery -- wry, witty, even sardonic -- has had dozens of imitators over the years, particularly at NBC. But few, if any, of his imitators can match his professionalism as a reporter and writer.

He has covered most major stories over the past 30 years for the network and is considered a master of the particular art needed for political convention and election-night coverage. Brinkley is credited, in large part, with maintaining high ratings for NBC last year when he left his sick bed following a gall bladder operation to appear on the network election night.

Brinkley said yesterday that "I've been talking to NBC about leaving since early this summer."

But because of the many changes in the top management of NBC and the parent company RCA this summer, Brinkley said, "There wasn't anybody here. It's dragged and dragged and dragged."

Subsequently, then-NBC president Fred Silverman resigned and the new RCA chairman, Thornton Bradshaw, named Grant Tinker to replace him. Tinker, in turn, named Robert Mulholland as president of NBC.

Brinkley said he had talked to those three executives as well as his immediate boss, NBC News president William J. Small, regarding his plans, in recent weeks.

He is scheduled to appear on the first two telecasts this fall of "NBC Magazine With David Brinkley" before leaving the network.

There was an unconfirmed report yesterday that Chris Wallace had been offered but had turned down the anchor job on the low-rated magazine show when Brinkley leaves. Other network sources suggest no host will be named to replace Brinkley on his departure.

Reports circulated in New York yesterday suggesting that Brinkley's sudden resignation resulted from a continuing dispute with Small over salary matters, story choices for the magazine show and even the replacement in July of the program's executive producer, Paul Friedman.

Those reports suggested that Brinkley had gone to several top NBC executives with an ultimatum that if Small remained he would go.

Referring to those reports, Brinkley said yesterday his departure "had nothing to do with Small. That's a b------- scenario."

Small yesterday also denied the reports, although he added that "obviously David didn't leave because things were going smoothly.

"David came to us and said he was leaving," Small pointed out. "We all hate to lose him -- we wish he would stay."

In Burbank yesterday, NBC chairman and chief executive officer Tinker said that he had met with Brinkley in New York on Monday.

"I asked him directly," Tinker said, "if his relationship with Bill Small had anything to do with his decision -- I'd heard the same reports.

"He went to some trouble to deny it," Tinker said. "David made it very clear that the much larger problem was that he just wasn't able to do the kind of thing he likes to do and does best -- the thing he is so justly famous for. There was just no forum for him.

"And that," Tinker added, "was by far the real reason David is leaving."

Tinker added that he didn't want to comment in any way on the "relationship of the two men."

In the statement released by the network yesterday, Brinkley wrote that "I will miss the place where, quite literally, television journalism and I grew up together. I am grateful to NBC and I will always miss it and wish it well."

And in the same prepared statement, Small said "everyone at NBC regrets that David has decided to retire after one of the most remarkable careers in broadcast journalism. I had hoped that David would stay with us for many more years. His insights, his knowledge and his way with words are distinctive and very special. He is the consummate pro. For the rest of us, it is like losing the home run king . . .

"His departure from NBC News leaves a very big gap. We, all of us, wish him well in the years to come."

Brinkley began his broadcast career in Washington with NBC in 1943, after his discharge from the U.S. Army during World War II and following earlier experience as a reporter with the Wilmington (N.C.) Star-News in his home town and the United Press.

His major break occurred when he was teamed with Huntley at the 1956 political conventions, which led to their partnership on the evening news.

After Huntley retired, Brinkley became a commentator for the network and then again served from 1976 until October 1979 as co-anchor with John Chancellor on NBC Nightly News, taking over the revamped "Weekend" news magazine series for the network under its new title of "NBC Magazine With David Brinkley" in July, a year ago.