A strange yet familiar beat echoes from a two-story house at the Barry Farms public housing development in Anacostia.

It is a rat-tat-tat sound that seems to echo the rhythms of this hard-pressed community; a music made from tin cans, grates and whatever else its players can scour from neighborhood alleys and empty lots.

The crude and innovative sound belongs to the Barry Farms Junkyard Band, made up of youths who for the last four years have taken their music around the city, playing street corners and city parks.

The group's talent for transforming junk into playable instruments has earned them a growing reputation in Washington for novel musical arrangements.

The sound is "junk funk. It's taking the music from the streets--talking about life," said band leader Derrick McCrae.

"Okay, lets start off with 'The Word,' " yells McCrae. The musicians take up their toy and handmade instruments and begin to play while one youth sings, twists and turns his body to the junkyard beat. In the middle of the song, they switch the beat and begin another tune, "Bottoms Up."

For most of the members, the band is a way of staying out of trouble and off the street. But it also is a chance to travel and perform at places that would otherwise be inaccessible. They have entertained on national and local television programs, at dozens of D.C. recreation centers, the Washington Coliseum, the National Geographic Society and during half time at football and basketball games.

One of the group's favorite show spots is in front of Deli 'N Dogs, a restaurant at 1904 M St. NW., right in the flow of the single-minded set eddying through the discos and fern bars.

Dave Zeiger, the restaurant manager, feeds and pays the group a "confidential" amount to perform there Friday and Saturday nights.

"I like the kids and their music, and it certainly is not bad for business," Zeiger said. "They are young guys out here having a good time. People smile when they see the band. Their music is very natural, completely opposed to the disco music at the many bars next door." The group also does very well in tips, he added.

McCrae, 21, sets stern rules for the members of the band. "They have to have at least a C average in school. I don't take dummies. They have to come with a clean mouth and have discipline. They must also have the approval of their mothers to join," he said.

One of the original members, 14-year-old bucket player Ervin Holton, said he helped to create the band four years ago. It all started on his back porch when Holton, McCrae and a few friends began banging a beat from a gallon bucket, he said.

"After a while, more people came around with more junk instruments," Holton said. Neighbors also have supported the group by donating a real trumpet and drum set. "The neighborhood has been very, very good to us," said McCrae, a clerk at the D.C. Police Department, who plans to attend the University of the District of Columbia this fall.

Robert Smith, 13, started playing in the band just before school let out this year. "The band helps to keep me off the streets and away from people trying to sell me drugs at night," he said. "Besides, it makes my mother proud of me. She doesn't mind as long as I don't get in trouble."

"It has taught me to use good manners, how to treat people--show your home training," said Steve Herrion, 17. "People seem to appreciate us more when we play at different places."

Herrion, who wants to become a singer, said the receptive response from audiences has helped him overcome his stage fright.

"I used to be scared to death to perform in front of people. But I learned to close my eyes and listen to the crowd. Now singing in front of large crowds doesn't bother me anymore," he said.

Most of the band members do not want to become professional musicians. "It's too hard to make it," they yell. One said he wants to become a lawyer while another said he wants to be an engineer.

"What they are doing now is fine to keep them off the streets, but I try to discourage them from thinking seriously about becoming musicians," McCrae said. "You have to be very lucky to make it in music. I want them to pursue other professional careers and to be all they can be."