No signal on rooftop dish. Question on setting up portable

If you have a coax connector that is labeled "cable tv" in a bay outside, you might try connecting your portable dish to that. That run of coax usually goes to a switch box near the TV before it hits a splitter. Take the coax end at the switch box off, and connect it to your sat. receiver input. You may need a jump cable to reach it. It is probably only RG59 instead of preferred RG6 but I used RG59 years ago to do exactly what I am suggesting. That was however, before HD.