The 6.5 million listeners who tune in Big Jimbo don't know what they are going to get tonight. Bohannon manages to turn this into a plus.

Big Jim Bohannon doesn't shy away from anything. His evening talk show is rated No. 6 in the nation, and he has 6.5 million listeners. We have come to watch and hear him in the Westwood. One studios, just to see how he does it, how this cool, laid-back man excites so many people. The studios sit atop a filing-cabinet-style building in Crystal City, Va., just across the Potomac River from Washington.

A call upstairs on a special security phone brings an unattended elevator to whisk us to the 12th floor. We are met by Jane Hautanen, evening producer of the Jim Bohannon Show, and taken through a maze of corridors into the newsroom. Jane is one of two producers. Rita Rich, the daytime producer, handles the bookings for guests during the hours most people are awake.

Jane is tense, collected, organized. She has been the night producer since Nov. 25, 1995. Her job is to make sure that everything happens when it is supposed to happen. She meets guests and escorts them to the holding room. She makes sure that guests to be interviewed by telephone or satellite are in place. She screens callers and puts them on line for the host.

Bohannon is sitting at this news desk calmly fooling with a computer while millions of people wait to hear his voice. He is a fine physical specimen with a red beard and red hair that probably is not as thick as he remembers it.

Although signs on the wall still proclaim this to be the newsroom of the Mutual Broadcasting System, it is now the newsroom of Westwood One. As Bohannon explains patiently, Westwood bought Mutual Radio, then it bought NBC Radio. Then Infinity Broadcasting bought Westwood, cum Mutual and NBC. Then CBS bought Infinity, and CBS already was owned by Westinghouse. Go that?

Thus, as we talk to Jim about the upcoming show, Charles Van Dyke of NBC Radio is preparing his 10 o'clock news feed, and his colleague, Sam Litzenger, sitting back to back, is preparing the 10 o'clock Mutual Radio feed. The CNN Radio feed, which comes from Atlanta, will be beamed to Westwood's central control room for distribution to radio nationwide. The CBS news feed, which comes from the CBS studios at 2020 M Street in Northwest Washington, also will be distributed through the same facility. Every morning, Infinity Broadcasting, which owns the G. Gordon Liddy show, will send the feed from WJFK in Fairfax, Va., to the Westwood mid-Atlantic control center which, as noted, also is owned by Infinity. And, in the same studios where Jim will do his show for Westwood, Mary Matalin just that afternoon was doing her show for CBS.

Bohannon has his lineup for this evening: From 10 p.m. to 10:30 p.m., Sen. Joseph Lieberman, Democrat of Connecticut, will be connected by telephone to talk politics and tell about his bill to curb TV violence; from 10:30 p.m. to 11 p.m., it will be Larry Korb, former assistant secretary of defense in the Bush administration, to talk about Saddam Hussein's refusal to allow U.N. arms inspectors to look for biological weapons; at 11 p.m., Susan Estrich will be in the studio to talk about -- get this -- her diet book.

We amble through Master Control, a massive set of aging consoles that handle all the broadcast traffic. The dials and buttons are just beginning to make way for a new computerized switching system. Master Control can handle 44 outgoing channels simultaneously, which is why it has become the switching center of choice for so many network programs.

At last we get to Studio B. Here at least is a bit of glitz where microphones are cantilevered over a kidney-shaped desk. Jim sits at the end with a computer on another cantilever; this screen will be his connection with the control room, the phone lines and the wire services while he is on the air. At hand is the inevitable mug of coffee, with a military crest inscribed "Fort Devens ASA." "I was in the Army Security Agency when I was in the service," he explains.

It is 10:05 p.m. on the big precision clock with the manufacturer's label FAGAG. "It's showtime!" shouts Bohannon, his face beaming, as though a light bulb went on inside his head. Then the red sign flashes "ON AIR." In the control room at 10"06 p.m., Jim Harmon, a large, pleasant-faced man, almost as laid-back as Jim, starts the theme music -- "Bohannon's Beat" by Hamilton Bohannon, a friend, but no relation.

The music are lyrics of the musical theme are infectious, "I told her when it comes to talking I'm the sweetest sweet talker in the world. Well, she said, you better start talking..." Harmon's arm comes down, pointing directly at Jim through the glass. "Hi there," says Jim evenly, "we appreciate your presence, and we appreciate any phone calls you want to send our way. 1-800-998-JIMBO." Sen. Lieberman is on the line immediately talking about not spending the projected budget surplus and the dim chance of campaign-finance reform.

Bohannon is asking intelligent, fact-laden questions. he is listening intently. He knows this stuff. Then we go to break and, when we come back, Scott in Harrisburg, Pa., is on the line alerting Lieberman about a Nuclear Regulatory Commission action. The senator thanks him. Then Monica in Boca Raton, Fla., is on the line. If there is a surplus, she asks, why not pay back the deficiencies in the Social Security trust fund? A good idea, the senator says, and his half-hour with the 6.5 million listeners is up.

After the break, Jim starts the segment with a sound bite from Secretary of State Madeleine Albright saying that we need time for a diplomatic solution in Iraq. Bohannon grumpfs. "This is Foggy Bottom-speak, meaning that we still plan to bluff them," he comments.

Then it's Korb, the disarmament expert now at the Brookings Institution, a nerd's nerd who gives a counterargument to Albright in nerdspeak. This doesn't rattle Bohannon at all. Turning quickly to the search function on the computer, he pulls up the latest statements from the U.N. inspection team.

Jim has his own ballpoint pens in his shirt pocket, and he gracefully crosses swords with Korb in a masterful fencing match. The computer is just a source of information, not a crunch. He rolls off the names of the countries on the inspection team, each word clipped and articulate, just like a master of 38 years of radio should. It's like the Olympic skater doing the quadruple lutz and landing easily on his feet. We hear from John in Utica, N.Y., and Robert in West Palm Beach, Fla. Then Korb's turn is over.

After the break, at 11:06 p.m., it's Estrich, in person. She flies into the studio in a cloud of pixie dust. This is not the Susan Estrich who as director of the Michael Dukakis presidential campaign lost 40 states. this is the Susan Estrich who has lost 40 pounds and has written a book about it. All of her feminist friends are green with envy, and they are mad at her for betraying the cause by seeking to look svelte. But Susan doesn't care; she looks and sounds like an understudy for Carol Channing. Personality trumps in ideology every time.

This woman says she thinks there is nothing wrong with being blond, beautiful and smart. Her book is for smart women who want to look beautiful. Susan undoubtedly is smart; she was a tenured professor of law at Harvard, and now she's at the University of Southern California Law School. Her two kids, Isabel, 7, and James, 4, have tempered her views.

Bohannon is swept into this whirlwind and soon is trading compliments, excusing the faux pas of commenting on a woman's looks by pointing out that her looks are part of the story. Here she is: two strands of pearls, pink cashmere sweater, black stirrup pants, glittery bracelets. Who says diamonds are not a girl's best friend? Media savvy, she pounds her points directly into the microphone, dispensing advice to one and all.

Surprisingly, most of the callers are guys, even though its a diet book for women. Tim calls from Wyoming, Mich., proudly announcing he has lost 150 pounds, down from 450. Louis calls from Burlington, Vt., and says he has signed up to go into the Army in July and is worried about basic training. Bohannon advises him to begin a workout regimen prior to basic training. "That's your job from now to July," he says. Estrich agrees.

Susan gives some more of her philosophy. "Being smart is great, but being smart and fit is better," she says. She says she lifts weights every day and can do "25 boy-pushups." Before, she couldn't even do one. Then she too is gone.

It's 12:06 a.m. on the FAGAG clock, and now its open-line time, when callers can talk on any subject they want. Jim starts things out by reading the results of a University of Chicago study on sexual activity. This gets things stirred up, of course. During the break, he says, "You never know when they're putting you on."

After the break Barbara from Edison, N.J., calls in to complain about an earlier remark concerning Dr. Jack Kevorkian. Even though she has lived a long life without one of her kidneys, and a bowel that had to be removed, she says that Kevorkian has it all wrong about people who suffer. "Nothing would make me trade one spring day, or one chocolate ice cream."

At 12:30 a.m., Jim opens the segment with a cute prerecorded bit in which he appears to interview ticket sellers in four cities about the going prices for the Super Bowl. It is a nice little turn, in which he asks the questions live, while the sound bites -- which came in a prerecorded feed -- sound like answers to his script. Soon we are hearing from Kimberly in Texas, and Matt in Rolla, Mo., Jim's home state. Then Jim in Coco Beach, Fla., calls in with a questionable, but funny, joke, and John in Santa Rosa, Calif., a military man, goes back to the Saddam Hussein question. Jim pushes the search key on his computer and is reading a news update that came in after the 10:30 p.m. segment with Korb. Bohannon takes time to wish Happy Birthday to his Mom, laughing that she is asleep at this hour. Ray, from Atwater, Calif., calls in at 12:57 a.m., and has only one minute. Then that's it.

Off the air, Jim chats about his show. "I try to elicit information -- which seems awfully straightforward and ordinary, except that is not the agenda of more than a few talk-show hosts. Most just want to make themselves look good or smart, or shed heat instead of light.

"And that's not a scattershot indictment of my colleagues, but it certainly is true of some of them. I just want to elicit information -- get interesting people on, ask them questions, and ask them in the right way. That's what I like to do, that's my goal. We have a variety of guests.

"If you tune in to a lot of talk shows, you pretty much know what you're going to get. That doesn't make them bad; it's what makes them successful. If you tune into Rush, or Liddy, you are going to get conservative politics, and if you tune into Laura, you're going to get tough love. And if you tune into me, you don't know what the hell you're going to get. To me that's a plus."

That's the Bohannon beat.