He's a singer, songwriter, actor, activist, ecologist and aspiring space traveler. But what John Denver really wants to be right now is heard on the radio again.

"We always had to struggle to get my records on the air. But when we did, I had incredible success," he said in an interview here at the start of his American tour. "One of the problems I've always had - even at the height of my career - was that I was never a radio darling. I didn't have the hype going that a lot of rock singers had. That mystique was just not part of what I was doing."The format at a lot of the stations now is not the kind of songs or kind of sound I'm doing. I still like to use a real orchestra, not a synthesizer or a drum machine. Real people, live music. But that's not what's going on out there right now."

The 44-year-old Denver is out with a new album - "Higher Ground" - on his own label, Windstar. The LP is being distrubuted by Allegiance Rec-ords of Hollywood, Calif. Denver left RCA Records after 25 albums, 13 of which went gold and eight platinum in the U.S. alone.

His easy-listening, country-crossover style made a string of hit singles in the 1970s: "Rocky Mountain High," "Sunshine on My Shoulder," "Back Home Again," "Annie's Song," "Take Me Home, Country Road" and "Thank . . . I'm a Country Boy." His greatest hits LP still ranks as the best-selling album in RCA history.

"They really took me for granted," Denver said. "I was one of the few artists on the label and I probably had the best contract they had and I was in the black. At the time I delivered my last album (`One World' in 1986), RCA had just been sold to General Electric and I was in line for a new contract. I had every right to expect as good a contract as I had, if not better.

"But the new management wanted to show a profit quickly and it was more than they wanted to spend. RCA's promotional people never supported me anyway. Radio was resistent to me and I was a hard sell, so why bother?

"One of the reasons for establishing my own label was to have the clout and the budget to say, `This is what I want to be done' and get this record on the air."

The new LP is in the same vein as Denver's others. It's heavy on love ballads - "For You," "Never a Doubt" and "Whispering Jesse."

"I'm a hopeless romantic," said Denver, who in August married Australian singer Cassandra Delaney.

Other cuts mix Denver's vocals and acoustic guitar work with his usual introspective lyrics ("Higher Ground," "All This Joy," "Country Girl in Paris") while other songs are for causes - "Sing Australia" written for Australia's bicentennial, "Bread & Roses" for the feminist movement and "Fallen Leaves (The Refugees)" for the world's homeless.

Denver has traveled the globe for concerts and benefits in his 20-year career. He visited Africa in 1985 to call attention to the hunger problem and did fund-raising shows in 1987 for the victims of the Chernobyl nuclear power accident in the Soviet Union. In 1976, he helped establish in Snowmass, Colo., the Windstar Foundation, which is working toward world peace and world ecology.

"One of the problems in the world today is most of us think the problems or the bureaucracies are so great that we can't make a difference," he said. "I want to prove that to be inaccurate. I want to demonstrate that an individual can make a difference."

Born John Deutschendorf in Roswell, N.M., and raised in Oklahoma, Arizona and Texas as an Air Force brat, Denver moved to Los Angeles to be a folk musician and wrote the mega-hit "Leavin' on a Jet Plane" in 1969.

He now is a licensed jet pilot and said he has longed for space travel since he was 10 years old, when he looked up at the stars one night and "was just enthralled with wonder of what was up there."

Denver was instrumental in the start of the Citizens for Space program and even volunteered to be the first to go.

Now that NASA has decided to put the citizen's program on hold following the ill-fated Challenger mission two years ago, Denver had considered going on a Soviet flight in December 1989. However, he missed the Nov. 1 deadline and balked at the $10 million price he said the Soviets wanted him to pay.

"I'm not willing to pay that. It's not ethical and it makes it look like whoever can come up with $10 million can fly in space.

"I don't want this to look like a stunt. I want to do something up there. I'd like to do a radio program for the week I'm up there for children all over the world and also host a television show."

Denver, best remembered on the silver screen for his role in "Oh God!," recently starred in a summer TV movie called "Higher Ground" about an Alaskan bush pilot.

Plans for a series were scrapped so Denver could embark on his current "Songs of the Future, Songs of the Past" concert tour, which began Oct. 5 at Arizona State University and will criss-cross the country through Dec. 18.

"Life is really going great for me now," Denver said. "I feel great about the quality of work I'm doing and the way the record's being received. I just got married again. I'm 44 and it's like I'm starting all over again. I've never been happier."