In ham radio, CQ is a call to anyone listening on a particular radio frequency, meaning "I wish to contact any amateur station". When an operator sends "K" or says "Go Ahead" after calling CQ, it's an invitation for any licensed radio station to respond. Here are some tips for using CQ: Be enthusiastic: Some say you should call CQ like your life depends on it. Use directed CQ: You can call CQDX to look for someone in a specific area, such as CQDX Europe. Use Q-codes: Q-codes are an international