Argh! It’s over for the Portland Radio Authority, once the city’s most notorious pirate radio station. The Federal Communications Commission chased the PRA’s illegal, 100-watt signal for three years before busting its downtown studio in 2006 (“Shipwrecked,” WW, March 8, 2006). PRA went online and legit but announced this week that it’s ending a decade of anarchic broadcasts Sept. 30 to merge with music station XRAY 91.1 FM.