As kpmacac said it will not work through the cable TV inlet. Especially if you have the little amplifier in line. If you bypass that it will work. Do a search there are several threads, some with pictures, on how to bypass it.
There are several ways to do it. Winegard recommends the diagram below.
Making the connections the way Winegard recommends does not require adding any coax connectors to the wallplate.
Note that this assumes your front TV is connected to the coax connector on the front of the wall plate. If yours isn't, there should be a splitter in the line labeled "To second TV" that will send the signal to both the front and rear TVs (if you have two TVs).
What Winegard calls a "power supply" below is the wall plate with the antenna booster switch and LED showing when the amplifier is on.
If you still want to be able to use the external cable in for both cable TV and the external dish just add an A/B switch to switch the incoming coax from the sat receiver "sat input" to the sat receiver "TV input".
One thing not shown in the diagram is using the RCA type connections or the better quality "component" type output or the HDMI (best) output between the sat receiver and the TV.
That will yield a much better picture with no interference from any local channels. You have to select a "video in" with your TV menu instead of using channel 3 (for example).
Some newer satellite receivers don't have a coax output so you may have to use HDMI or component connections.
If you have a video distribution box that will have to be taken into account.
Clay (WA5NMR), Lee (Wife), Katie & Kelli (cats).
Fixed domicile after 1 year of snowbirding and eleven years Full Timing in a 2004 Winnebago Sightseer 35N, Workhorse chassis, Honda Accord toad
Only problem now is that the rv cable/satellite connection doesn't work for the satellite.
You have a new RV, you should not have to do any rewiring.
Check and see if you have 2 outputs near your entertainment center. The sat. signal does not usually work thru the tv outlet. Also, turn off the signal booster for the antennae. With most of today's rvs, the signal will run thru the cable line. Mine does. My old one wouldn't
If you cannot get it to work, the diagram someone posted will do the job.