James Brown, a television announcer for CBS Sports and former All-Met basketball player at DeMatha High School, has joined the group of investors seeking an expansion baseball team for Northern Virginia, Brown and the group's leader Mark Tracz said yesterday.

Tracz also said the group's presentation before the National League Expansion Committee has been scheduled for Sept. 19 in New York. He said the league had informed him groups may not be represented by more than five people and will have 30-45 minutes to state their cases.

In addition, Tracz and group vice president Ira Saul disclosed two of the sites under consideration for a stadium. If it acquires one of the two teams the NL will add in 1993, the group intends to initially locate the team at RFK Stadium, then move to a new facility.

Among the possible stadium sites are a portion of the Fort Belvoir Proving Grounds the group believes it can acquire, and the current site of Prince William County Stadium in Woodbridge, home of the Class A Prince William Cannons.

Tracz, president and part-owner of the Cannons, said the Prince William facility occupies only 20 acres of a 90-acre parcel that might be able to accommodate a major league stadium. The group already has a contract with option to buy on a 170-acre parcel near Dulles Airport. It also is examining sites in Fairfax County and the City of Alexandria, Tracz said.

The group also is eying the Prince William stadium site as it makes a separate decision on whether to apply for one of the two Class AAA and Class AA franchises that will be created with the major league expansion. The Prince William County Park Authority, which owns Prince William County Stadium, has agreed to support those efforts.

Accommodating a Class AAA or Class AA team would involve expanding the stadium's seating capacity from 6,200 and improving its other facilities. Class AAA officials are requesting that expansion applicants have a stadium that seats at least 10,000.

Tracz said minor league expansion teams would bolster the group's bid for a major league club as well as add to his holdings. If his group obtains a Class AAA or AA team, Tracz said the Cannons would be relocated.

"The major league team is the key, however," Tracz said. "We don't want it {the Class AAA and Class AA expansions} to take away from the focus on getting a major league team. That takes a lot of time and energy."

Much of the group's energies recently has been focused on Brown. A District resident and Harvard University graduate, he will be the second minority member among the group's eight-person general partnership entity. Former tennis champion Arthur Ashe already is a part of the controlling group.

"Baseball is my first love," said Brown, adding DeMatha basketball coach Morgan Wootten discovered him while he was playing for a youth baseball team.

Brown said he consulted with attorney Craig Foster about a possible conflict of interest between being a part-owner of a major league team and an employee of the network that holds the broadcast television rights to major league baseball until the end of the 1993 season. Brown said it would not be a problem because he is not involved with CBS's baseball broadcasts.

Foster could not be reached for comment. CBS spokeswoman Sandy Genelius said the network did not have enough information about Brown's involvement with the baseball group to comment.

In another development, Tracz said the group is seeking someone to help it lobby baseball's owners, and will be interviewing a candidate this weekend. He declined to name the candidate. A group from the Tampa-St. Petersburg area has hired Barry Rona, former executive director of the Player Relations Committee, for a similar job. The PRC is the owners' bargaining arm in negotiations with the Major League Baseball Players Association.