An unlikely coalition of activist groups, satellite and cable providers, and independent TV channels have teamed up to make trouble for Comcast Corp., Time Warner Inc. and the two companies’ $17.5 billion plan to carve up once-bankrupt Adelphia Corp.

The new group, which has called itself the Competition and Diversity Coalition on the Adelphia Transaction, includes: satellite providers DirecTV Group Inc. and EchoStar Satellite LLC; cable “overbuilder” RCN Corp.; public interest law firm Media Access Project; and Mid-Atlantic Sports Network, the channel for Major League Baseball’s Washington Nationals and Baltimore Orioles.