When you turn on the radio and tune to 93.1 on your dial, you expect to pick up your favorite station, Mix 93-1, except now it's not there or it's not coming in that clear. It's easy to explain -- tower light maintenance is going on this weekend and on Monday. The tower that the Mix 93-1 antenna is on to broadcast the station is also shared by 101.5 KNUE and Fox 51 TV. The tower is more than 1,000