It's the season for anniversaries -- the Kennedy Center and Wolf Trap recently celebrated a decade each, WETA celebrated two. Sitting not so quietly on its Northwest hill, WAMU-FM (88.5) is also celebrating 20 years of public service and psychic entertainment, what one newspaper described as far back as 1962 as "radio for grown-up minds." While most college-affiliated stations go about their business with little power and less outreach, the 50,-000-wat station has brought a certain class to Washington's airwaves.

"We tried to take the idea that you could be stimulating without having to be stuffy," says Susan Harmon, an 11-year veteran at WAMU and its manager for the last five years. "People simply didn't explore what you could do that was educational in he classic sense but had some relationship to contemporary radio habits and the fact that people don't listen to 45-minute pieces."

Although WAMU is housed by American University (which also contributes 3 percent of its annual budget of $900,000), the station has long been a nearly autonomous entity.

Having already built up a solid reputation in the '60s, WAMU managed to get in on the ground floor when the National Public Radio network began in 1970. In 1971, WAMU held its first on-the-air fund raiser and came up with $4,000. Last year, the total surpassed $300,000 one of the highest levels of listener support in the 250-station public radio system. WAMU has about 10,000 members (about 7 percent of its weekly audience); the rest of its funding comes from the Corporation from Public Broadcasting, National Endowment for the Arts and corporate contributions.

Onetime Joy Boy and longtime Washington radio personality Ed walker came to WAMU two years ago to program big-band music in the early afternoon. It was a return of sorts, since in 1951 Walker was a founder of WAMU-AM, the university's campus-only carrier-current station. He had tried as early as 1954 to start an FM station, but the Evening Star, which had given AU its broadcast building in exchange for permission to build its own radio-television tower on the high elevation of the AU campus, didn't want any competition for its WMAL-FM. In 1961, when WAMU-FM finally hit the airwaves, its programming was staid and exactly what one might expect from a college station: "A Salute to the New York Philharmonic," a religious program titled "The Bible: The Jewish Viewpoint," and programming about UNESCO, emerging Africa and "Inside Washington."

"Roger Penn [WAMU's first facilities engineer and later its general manager] always intended it should be a public station, not a 'college' station," says Ed Merritt, host of the "Brookmark" and "Nightwatch" programs and a WAMU veteran of almost two decades ("I'm the old man of the mountain"). "He wanted to create a facility that could counterprogram everything else that was going on in radio at the time, but he had to get something to fill in that hole."

It didn't take long for the station to dump programming stereotypes and achieve its own character, and over the years WAMU has been innovative and adventurous: Although it is an NPR station, WAMU produces 85 percent of its own programming; the 23 hours of weekly bluegrass programming are the most for any public station in the country; since 1963, John Hickman has broadcast the vintage radio shows that have all but disapeared from the airwaves they once ruled.

Merritt's "Bookmark" program, one of the few on the radio anywhere, has presented readings of many contemporary and classic works. "Map of an Inward Journey" by Alice Koller dealt with the author's experience as one of the few women to ever take a PhD in philosophy from Harvard and her subsequent confusion about her place in life. Seven years after beig read over the air, the book, retitled "An Unknown Woman: A Journey to Self-Discovery," will be published by Holt, Rinehart, Winston in the spring.

FRom 4 1/2 hours a day at 4,000 watts in 1961, WAMU has gone on to 24 hours of programming at 50,000 watts. Two years ago, NPR put up the first radio network satellite, "making news and special events much more accessible," according to Matt Coates, local producer of NPR's "Monitoring Edition." Top-notch news and public affairs programming are a big part of WAMU's continuing appeal. In fact, both "Morning Edition" and the award-winning "All Things Considered" (both carried by WAMU) could trace their roots to the station's still-running "Kaleidoscope" programming; "ATC" cohost Susan Stamberg got her start at WAMU, serving as producer and host of "Kaleidoscope," which once described itself as "a weeknightly gaze at the bummer called life . . . with a pastiche of views, opinions, commentary, conversations . . . absurd news, consumer information, books and theater." That sounds like a synopsis of "ATC."

There's also the Fred Fiske Show, in which the veteran Washington interviewer tackles a wide variety of tpics with listener call-ins. Fiske (one of the city's best-known radio personalities after many years at WWDC), Walker, Merritt and bluegrass host Jerry Gray represent another facet of WAMU's approach: All were experienced in commercial radio before coming to WAMU. While the station may serve as a training ground, it's for radio people, not for college students marginally interested in radio.

Susan Harmon remembers 10 years ago when "one year we had 16,000 listeners and the next year we had 14,000 and I said, 'My God! Two thousand of them died!'" With 165,000 listeners a week according to recent ratings, WAMU is abou t in the middle of the 40-station Washington market. Where most public and college-affiliated stations are known for classical, news or jazz programming, WAMU has accomplished a remarkable balancing act -- and somewhere down the line, its listeners will have to give thanks by giving money. Although WAMU has received a number of grants in the past two years (including a five-year station improvement grant that will total $1 million), Reagan budget cuts have caused it to reassess its funding situation.

At this point no one envisions any cutbacks in the station's staff, made up of 22 full-timers, 35 part timers and more than 200 volunteers; in 1979, when the Corporation for Public Broadcasting cited WAMU for outstanding achievement in local public broadcasting, it singled out its integration of volunteers. In the meantime, WAMU continues to expand its news department and maintain its state-of-the-art equipment.

It's a long way from the days of learning Japanese, Greek and German via the airwaves, from daily programming around a theme ("International Affairs" on Tuesdays) and the reliance on second-hand programming. It's even further from the days when Roger Penn tried to cut surplus computer tape into quarter-inch tape for reels. He couldn't cut it straight, but the station could and Washington has been all the richer for it.