I have an RCA SDTV. I try pressing the button to go to Digital, however, the only thing that happens is a #3 on a black screen. Nothing else comes on. I have to go back to the analog setting to get any channels. How do I access the digital channels. I am getting a converter box anyways. I only have rabbit ears antenna, and the picture on the analog is not good. To access the Digital part, do I need the converter box?