U.S. District Court Judge Oliver Gasch yesterday sentenced a General Services Administration contractor, who admitted receiving $900,000 from GSA for repairs never done, to six months in jail.

Gasch also accepted guilty pleas from two other GSA contractors and three former GSA employes involved in writing phony repair contracts in return for bribes.

The six-months jail term, plus 2 1/2 years of probation, was imposed on John P. Rudell, 60, an owner of Tuxedo Contractors Inc., of College Park. Tuxedo obtained $2.7 million in repair contracts from GSA for $1.8 million of legitimate work. Most of the remaining $900,000 was kicked back to the GSA employes who authorized the nonexistent work.

According to government sources, Rudell obtained contracts to tile the floors at the Central Intelligence Agency headquaters. But the amount of bogus tile for which he was paid would have been enough to cover a building six times the size of the Langley facility, according to the sources.

Marvin P. Sadur, Rudell's lawyer, told Judge Gasch that Rudell, who now lives in Wisconsin, had never been in trouble with the law before. He said Rudell goes to church and helps the YMCA.

"He probably will be debarred [from doing U.S. government work] for three years at least," Sadur said, adding that Rudell actually lost money on many of the contracts he received as a result of the bribes.

Assistant U.S. Attorney William S. Block said a jail sentence is "mandated" if such corruption is to be deterred in the future.

The former GSA employes entering gulity pleas yesterday were:

Robert E. Palmer, 55, of Washington, who is charged with authorizing phony contracts in return for $15,000 in kickbacks.

Robert E. Allision, 50, of Silver Spring, who is charged with receiving $40,000 to $75,000 in kickbacks from contractors.

Thomas M. Kearney, 43, of New Carrollton, who is charged with receiving kickbacks of $35,000 for authorizing nonexistent work.

The contractors who pleaded guilty were:

Albert Brand, 42, of alexandria, who is charged with giving $40,000 in gifts to GSA employes who then overstated the amount of his repair contracts by a like amount.

Alfred J. Pratt, 39, of Washington, who is charged with performing unspecified personal services for GSA employes so they would steer contracts to him.