A man who pleaded guilty in connection with an elaborate scheme to sell stolen computer plans to the Soviet Union has been sentenced to six years in federal prison. Kevin Anderson, 30, pleaded guilty in May to conspiracy to violate export laws and wire fraud in a plea bargain that apparently required his testimony against his alleged co-conspirator, Charles McVey. He had faced a maximum of 15 years. McVey is awaiting extradition from Canada for his role in the failed caper involving $4 million worth of technology manuals and programs from the Saxpy Corp. of Sunnyvale. Prosecutors had sought a sentence of 12 years for Anderson, citing the case's ``extraordinary seriousness.'' But U.S. District Judge William Ingram said at Friday's sentencing he was mainly concerned about the theft of materials from Saxpy and less about the purported danger to national security posed by the 1987 scheme, which was never completed. Because of the Saxpy computer's capabilities in antisubmarine warfare, the case threatened national security, prosecutors contended. ``The American computer technology involved in this case is among the most sophisticated and highly sought after by the Soviet bloc,'' the U.S. Department of Commerce said in a statement issued Friday. ``The documents and programs stolen from Saxpy would have allowed the Soviets to use this technology in anti-submarine warfare applicatons. ... If the shipments were successful, it would have been a major blow to our national security.'' Defense attorneys charged that federal officials had ``hyped'' charges in the case, saying they claimed Anderson had stolen ``the crown jewels of technology ... when it was really rhinestones at best.'' David Ellison, one of Anderson's attorneys, said that with credit for time served, Anderson could be free in 18 months.