The chairman of Planning Research Corp. has submitted his resignation, a source said yesterday, in what appears to be the latest in a series of management changes at the McLean-based government services and technology contractor.

Scott Thompson, who took over the company less than a year ago, submitted a letter of resignation last week, effective Jan. 15, the source said, after his powers were reduced in an executive reorganization by the company's parent, Towson, Md.-based Black & Decker Corp.

With annual revenue of $700 million, PRC is one of the Washington area's leading purveyors of management and computer services to the federal government.

Gary Kennedy, 37, was hired in November as president and chief executive officer of PRC and Thompson, 44, who had been president, was elevated to chairman, but with reduced responsibilities, sources said.

Thompson declined to comment yesterday on the report of his resignation, referring inquiries to PRC's corporate communications department. A PRC spokesman said he could not discuss the situation without permission from Kennedy, who was traveling. Kennedy did not return a telephone call.

The source said that Thompson's plans to leave the company, and the reshuffling of top executives that preceded them, appear to signal a new direction for PRC.

Kennedy was hired away from Oracle Complex Systems Corp., a subsidiary of Oracle Corp., a California computer software concern. Kennedy is believed to have been hired to diversify PRC's business toward commercial markets and away from government work.

PRC has gone through a trying period over the past couple of years as the result of a series of mergers and management changes.

The company was acquired in 1986 by Emhart Corp., a Connecticut conglomerate, which later added Advanced Technology Inc., another local government services firm.

As Emhart was trying to combine the two services companies, it was taken over itself by Black & Decker, which announced that it hoped to sell PRC and ATI.

But concerns about reduced federal spending on outside contractors -- especially at the Pentagon, a major user of companies like PRC and ATI -- soured the market and made the companies difficult to sell.

Last year, Black & Decker took the companies off the sales block and appointed Thompson, an ATI veteran, as the latest in a string of executives charged with making PRC and ATI work as a combined entity. Staff writer Cindy Skrzycki contributed to this report.