The hippest septuagenarian in Cobb County comes to work with a tote sack full of vinyl and fire in his eyes.

After playing his traditional 9 p.m. show opener — Father Tom Vaughn’s rollicking “Battle Hymn of the Republic” — and some stomping blues by Lou Donaldson, H. Johnson opens up the microphone.

“It’s 38 minutes after nine, we haven’t been here an hour yet and we’re already working up a sweat,” Johnson tells his listeners on WABE-FM before punching the button on a steaming side dish of Ray Charles.

“I get worked up,” says H. Johnson, leaping to his feet to locate something in the archives. “I start jumping up and down. But it keeps me alive.”

At 72, Johnson — the H is for Herman — is livelier than Oscar Peterson at tempo presto. He’s a cataract of swing and bonhomie. He has been spinning records on his Saturday night radio show, “Jazz Classics,” since the Carter administration, and has been on the air longer than anyone else at Atlanta’s 90.1 FM, including veteran program director Lois Reitzes.

“In the beginning, there was H,” says Reitzes.

Johnson arrived at the public radio station in 1978 as a temporary fill-in. “They had a fellow here who left, and they hired me until they found a suitable replacement,” he says. He takes a beat: “They’re still looking.”

If they’re looking to replace Johnson, give up now. He’s got three degrees in bebop and a Ph.D. in swing. Inside his head is an Alexandria of jazz arcana. He relates to that deep knowledge the way a 10-year-old boy relates to a Slip-N-Slide.

“He’s just having fun, he’s like a kid,” says comedian Jerry Farber, a friend and fellow pianist, who has seen more than a few corny jokes stolen by Johnson. “I listen better because of H.”

Tomorrow jazz trumpeter and vocalist Joe Gransden will bring his big band to play at a tribute party honoring Johnson’s three decades of service at WABE. The shindig, sponsored by the station and staged at Cafe 290 in Sandy Springs, will also be broadcast as a live show. Gransden says Johnson has special access to a motherlode of undiscovered gems. “You know, I do this for a living, and every week he is hipping me to new song or a new artist I’ve never heard of.”

Eclectic evening

Most of those revelations emerge from Johnson’s personal collection of several thousand vinyl records and perhaps an equal number of compact discs shelved at his Mableton home. The radio station maintains its own jazz library, but Johnson augments that with his own discs, which he brings back and forth each Saturday. He might carry 40 LPs in a cotton tote and another 40 to 80 CDs in shoebox-sized containers, all of which provide the raw material for a show.

Sometimes he ignores everything he’s brought. It depends on his mood and listener requests and the connections between artists and songs. Maybe he’ll play an Ellington recording of “Satin Doll,” from the 1940s, then a trio version of the same tune recorded 35 years later.

Right now Johnson is playing a requested 1958 Jimmy Smith recording, “The Sermon,” featuring 19-year-old trumpet prodigy Lee Morgan on the tune “Flamingo.” But that’s not how H. says it. He sings it: “Flaa-meeng-OOO!”

Singing, and scatting, are part of the performance. Tall, lean, white-haired and graceful, Johnson moves like a cat between two turntables and a multiple-CD player. His preferred broadcast style is grandiloquent, verging on self-parody. His voice is a baritone, with a sibilant touch of Sterling Holloway.

He will introduce the jazz violinist Stuff Smith with his full name — Hezekiah Leroy Gordon Smith — but then might break into song following a Count Basie cut.

“We’re sitting here suffering from an acute attack of good taste,” says the transplanted Yankee, while queuing a Thad Jones/Mel Lewis rave-up, “Don’t Get Sassy.” “I can’t talk right now,” he tells one caller, “I have an important executive here from the Pentagon.”

Sassy! That brings someone else to mind, and Johnson rummages through one of his boxes. “Aaah! Here it is! This is perfect!” he says, brandishing a recording by vocalist Sarah “Sassy” Vaughan.

From the heart

Marilyn, his wife of 31 years, watches these proceedings with bemused affection from a comfortable chair in the pocket-sized studio, her hair styled in a medium Afro, a black shawl drawn around her shoulders against the air-conditioned chill.

“He does his show just like a musician improvises,” she says. “I think that’s why he’s lasted so long: because it comes from the heart.”

Marilyn accompanies her husband every Saturday night, to listen, to chat, to offer a suggestion, if asked, and to drive home when he quits, exhausted, at 2 a.m.

“She’s part of the success of the program,” he says. Her taste leans toward the plain rather than the fancy. “She’s not interested in flatted fifths or diminished seconds or augmented whatever. Everything she’s ever told me to play on the air, I get a positive response to.”

She says her education came from H. His education began as a child back in Asbury Park, N.J., where William James “Count” Basie was a family friend, and often dropped by to play his mother’s piano.

After his parents amicably divorced — “My mother got the house and the car, my stepfather got me” — Johnson moved with his stepfather to Atlanta and went to Price High School, now a middle school.

Starting as a teenager, he’s worked at radio all over Atlanta, playing gospel, R&B, jazz and other formats, in stints at WAOK, WIGO, WRFG and WCLK. He was working at a record shop on Pryor Street when Marilyn’s little sister, Carolyn, walked in and he tried to get her phone number. Carolyn laughed and gave him Marilyn’s.

The rest, as they say, is matrimony.

Keeping classics alive

Johnson has a deep love for jazz piano, with the diminutive Erroll Garner as its chief prophet. Garner, 5-foot-2 in his stockinged feet, “was so short he could hide by standing up,” says Johnson. “When he got a stomachache, he hurt all over.”

Over the years, Johnson has struck up friendships with pianists including Garner, Bud Powell and Johnny O’Neal, along with many other jazz musicians.

He will sometimes act as an informal master of ceremonies at jazz concerts featuring performers he admires, and appears twice a month at Cafe 290 in Sandy Springs to introduce the Joe Gransden Big Band.

Gransden is one of many contemporary performers whose music Johnson will play, but Johnson’s heart is with music from the 1940s, ’50s and ’60s. He has a conservative’s sense of responsibility to the canon.

“I’m not going to play somebody just because they’re new,” he says. “I’m going to play somebody because they’re good. What tells me they’re good? My ears.”

His ears like music that swings. “Maybe that’s primitive,” he says, sliding a Lena Horne LP out of its sleeve. “Maybe I’m not as advanced as I should be, but I still gotta pop my fingers and pat my foot.”

Making new fans

After midnight, and his weekly selection of just the right version of “Round Midnight,” he plays more than a half-hour of Horne’s music, in tribute to the mighty singer who had just passed away.

WABE caters to listeners in the over-35 category — “Jazz Classics” finishes fifth in that demographic among other Saturday night radio shows — and yet Johnson has found some younger listeners by following his own muse.

“Every Saturday night, it’s Father Tom Vaughn,” longtime listener Martin Flaherty says of his 12-year-old son Michael Finn Flaherty’s listening choices. “On his iPod is Clash, Ramones, Iron Maiden and some hideous metal, but when it’s Saturday night at 9 p.m. he’s putting on ‘Jazz Classics.’ ”

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In the key of H

  • Scatting and improvising with WABE-FM jazz disc jockey H. Johnson:
  • On smooth jazz: "Smooth jazz stations come and they go. They don't last because you can hear better music on an elevator."
  • On the secret of the Modern Jazz Quartet's popularity: "I asked Milt Jackson one time, 'To what do you attribute your success?' He said, 'Ballads and blues.' "
  • On the sonata form: "Sonata? I'm familiar with Frank Sonata."
  • On exercise: "I ran three miles this morning. But they caught me and I had to give that lady her purse back."
  • On jazz rules: "Some people do a jazz program and they stay within the jazz idiom without exercising taste. I'm going to play some Barbra Streisand. She is not a, quote, jazz singer, but she is a, quote, great singer."

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Be there

“Tribute to H. Johnson” will take place 8:30 p.m., Monday, June 21, at Cafe 290, 290 Hilderbrand Drive N.E., in Sandy Springs, featuring Joe Gransden and His 16-Piece Big Band. The show, which is open to the public, will be filmed by Public Broadcasting Atlanta, PBA-30, for broadcast in the fall.

Tickets: $8; doors open at 7 p.m.

Information: 404-256-3942