It is almost airtime as Ernesto Perez rushes into the no-frills Atlanta studio of WRFG-FM—or Radio Free Georgia—and slips on his headphones. An environmental engineer by day. Perez hosts a two-hour music and call-in show. Con Saber Cubano (With a Cuban Flavor), on Tuesday night plus a general Latin show on Saturday. Now he is poised for his weekly bout with desperation, disguised as a friendly family gathering.

As always the core of his airwave "family" is formed by the 1,800 Cubans detained in the federal penitentiary located 10 miles across the city, well within range of WRFG's 50-mile broadcast radius. The detainees await deportation because they've been found dangerous and undesirable by the U.S. government, and Cuba refuses to take them back. These mostly young, mostly blank Marielitos came to the U.S. in the 1960 boat lift that saw 125,000 Cubans flee to Key West from Mariel. Virtually all the imprisoned have been convicted of crimes either in their homeland or the U.S., and although most have served their sentences, they remain in a legal limbo, without formal charges against them and with little hope for release any time soon. Federal courts have ruled that such men have no constitutional rights and can be detained indefinitely.

Tonight Perez, 39, must be especially careful to ease the frustrations of the inmates and their friends and relatives outside the prison. Three homicides since October and 18 months of 23 hour-a-day, eight-to-a-cell confinement for more than a third of the Cubans have raised tempers to the flash point. Moreover, since the Cubans—now about 75 percent of the inmate population—began arriving at the prison six years ago, six previous homicides, seven suicides, 400 suicide attempts and more than 2,000 self-mutilation incidents have been reported. A riot took place in 1984 and a hunger strike occurred the following year. "Their conditions are pathetic," Perez says, "but my job is to raise their spirits, not their anger."

As the opening salsa beat fades, Perez' deep, modulated voice welcomes listeners in Spanish and English, inviting them to request songs and phone in messages. Suddenly the red light signaling a caller blinks on. "Sí?" says Perez, who himself was detained for three months in a Florida refugee camp at age 16. (He was one of the thousands of Cuban teenagers sent to America by their parents in the early '60s.) A familiar caller named Guillermina asks Perez to play a romantic song for her husband in the prison. "You got that?" she says. In Spanish he answers, "That's why I'm here, love," and quickly puts a José Feliciano ballad on the turntable.

The red light blinks again. It's Tanya, who dedicates a song to her boyfriend, Miguel. For her, Perez offers up a plaintive piece by Julio Iglesias. "My show's cultural," he says, off the air, "but when callers or guests talk politics or the law I'm objective. It's like a big family at dinner with a lot to say. Someone's got to keep cool."

Between a note on the history of Cuban music and a sponsor's spot, Perez answers a call from Guillermina's husband, who sends her an embrace. Midway through the show, Perez interviews a trombonist in a local salsa group, who is also a translator at the prison. Both men and the callers avoid mentioning the obvious: the prisoners' legal status and the overcrowded conditions that at least one visiting U.S. Congressman, Wisconsin Democrat Robert W. Kastenmeier, recently termed "intolerable" and "beneath us as a society." Off the air, Perez explains that most guests and callers "police" their words because complaints might lead to harsher treatment. Retiring warden Jack Hanberry has denied that prison officials monitor the show, even though, he says, "Some of our guys have heard it from time to time." He has also denied that his announced retirement (on July 3) at age 50 is linked to the inmate killings, adding, "No other institution has inmates as volatile as the Cubans."

Perez hurries to include one more call before the program ends. It's from one of a trickle of ex-inmates living in halfway houses as a transition to normal life. He's calling to tell his prison buddies to "persevere" and "keep listening to Ernesto. Sometimes you were about all that kept me alive. Thanks, brother."

At 9 p.m. Perez removes his headset and gathers his albums. He recalls that he was kept "spiritually alive" by a few good-hearted teachers at a Catholic boys' home in Albuquerque, where he was sent after leaving the camp in Florida. (In 1967, when he was 20, his father, a professor, his mother, a teacher, and a younger sister arrived from Cuba.) After completing a B.S. in civil engineering at the University of New Mexico and spending three years developing offshore oil and gas fields in Louisiana, Perez returned to school, earning a master's degree in environmental engineering. He now works for the Environmental Protection Agency, reviewing industrial and waste water plants for compliance with EPA guidelines.

"I've done radio for eight years," he says, moving into the hallway, a soulful jazz riff following him to the stairs, "not for the pay—because there isn't any—but because I love the music, and because I'm Cuban and feel for those men." Arriving at his two-story house in northeast Atlanta, Perez toots the horn. His wife, Lourdes, 33, a Coca-Cola executive secretary, opens the door in the carport and their 4-year-old son, Ernestico, peeks out. Perez, who also has an 8-year-old daughter by a previous marriage, clicks off the ignition. "This is my real family," he says, "but some nights I think it's in that prison."