Ernest Tubb, the 67-year-old Country Music Hall of Famer, sat in his tour bus Saturday at the 31st National Championship Country Music Contest at the Prince William County Fairgrounds in Manassas, Va. He was waiting to perform the first of his two concerts that evening. "I remember my first amateur contest," he said, his hands folded on a coffee table, a Grand Old Opry ring the size of a lug nut on one finger. "I was 16 back in San Antonio. . . You know that old saying about the danger of appearing with a kid or a dog. Well, I came in second. The kid beat me."

A crowd of about 6,000 country music fans, packing lawn chairs, coolers, straw hats and umbrellas, flocked to the fairgrounds Saturday afternoon, including 135 aspiring musicians competing for part of the $5,550 in cash awards. A much larger crowd and many more registrants were expected yesterday.

An early arrival Saturday was Connie B. Gay, the Washington radio pioneer who started the contest along with the Warrenton-Fauquier Jaycees back in 1950. Gay, who's no longer involved with the event, believes the contest was moved for reasons of space and parking. "We had to move from the original horse show grounds after only two years and it's been building steadily ever since. . . Of course we've had some luck. Roy Clark won that first year. Then came Patsy Cline, the Stoneman Family, Chubby Wise. . . We've always had a lot of people interested in it."

Now more than ever it seems. Dozens of guitar and banjo cases littered the lawn surrounding a small open-air booth where registrants huddled in line waiting to audition before three preliminary judges. Many waited three, four, sometimes five hours to get a chance to perform in one of 12 categories, ranging from bluegrass and traditional country music to contemporary and "miscellaneous" styles.

The music and musicians were surprisingly diverse: 11-year-old Shari Warren from Catlett, Va., whispered an Olivia Newton-John tune; Terry Hoffman, a Mt. Royal, Va., teacher, favored the traditional "Cotton Bolls"; Lee Fontenot and the New Orleans Goodtimers, one of several professional bands, silenced the competition with their western swing; Derrick Ford from Dell City, Va., went so far as to plug in his Stratocaster and play his variation of a Jimi Hendrix blues. The judges were bowled over.

"Everybody passed the auditions but one person," said Joe Wheeler, the same preliminary judge who auditioned Roy Clark back in 1950. "I got to admit some were pretty close to failing, but you got to keep in mind how far some of these folks travel. Bristol, Roanoke . . . here's one registered from New Jersey, another from Florida. . . We're just here to make sure they don't freeze on stage."

Mike Wampler, last year's male vocalist winner, agreed. "They just want to make sure you can carry a tune. But the talent in general has come a long way. There's a lot more pickers now. It's worth it just to stay and listen. You can learn a lot."

Foremost among the lessons to be learned was how to impress a panel of music industry judges and several thousand fans fast -- very fast. No performance could last longer than three minutes for singers or two minutes for instrumentalists without being penalized.

Two stages were set up facing the grandstands so that as soon as one song was over another began. Older folks in the crowd staked umbrellas behind lawn chairs. Younger fans took to the grandstands or stretched out in the broiling sun on quilts as a seemingly endless and wildly uneven group of country hopefuls paraded before them.

"Get out of here, you turkey!" shouted a woman in the bleachers when a would-be Freddy Fender failed to come within hailing distance of the right key. Another swooned when B. J. Parratt of Rockville walked out, his chubby frame packed into Elvis jump suit, crowned by a belt buckle large enough to pass for a license plate.

There was no shortage, too, of country queens decked out in full cowboy regalia -- hats and boots and fringe to spare. A few struck convincing Emmylou Harris poses; others looked more like someone who would take your order in a western steak house. One moment you were watching the Grand Ole Opry, the next moment the Grand Ole Gong Show.

Still, the crowd rewarded just about everyone for their effort with warm applause, and when the musicians were good, they were very good.

The Gaithersburg band "Shades of Blue" was among the first to get a rise out of the crowd. So were "Kim and Karmen," the daughters of Harold Reid, a member of the Statler Brothers. But this was just the beginning of an exhausting 20-hour competition.The names of the musicians who would join Patsy and Roy and countless other winners weren't scheduled to be announced until late last night.

Last year when the 30th National Championship Country Music Contest was held at Lake Whippoorwill in Warrenton, Va., it rained so hard that spectators seated on the hillside fronting the stage soon found themselves sliding -- so hard that Jerry Lee Lewis, the featured headliner, was forced to end his concert after performing only 20 minutes. So hard that the judging of the finalists was postponed for two weeks. So hard, some day, that that's the reason they decided to move the contest this year to the Prince William County Fairgrounds in Manassas, Va.