I'm not sure on the R29 but on the C 28 it is on the port side above a closet.
There should be an amplifier for it. Mine is a small white box with a green led light. The led only lights when the house power is switched on. If someone who has/ knows where the amplifier box is located on the R29 you can make sure both TV cables are attached to it. The box is approximately 3" x 2".
Sorry I couldn't be more helpful on the location of said box but I thought I at would least tell you what to look for.
I had a similar problem with my boat as the previous owner damaged the TV cable at the attachment to the box. Search and search but no channels even in downtown Tampa. I knew something was wrong!
Terry