I currently have Dish satellite, but I am looking for a way out. So, I am looking at alternatives. I have had good luck with Plex before, so it seems to be a viable option. I currently have one smart TV, an LG flat panel, and a smaller Motorola flat panel in the bedroom. The 2 main TVs (of 3 total) have a Chromecast USB device, the smaller 3rd TV has a ROKU.
What do I need to get all three TVs off satellite, and onto Plex live TV? Do I need a digital tuner if all my TVs have digital tuner built into it already? I already have Plex Media Server running on my main PC, to view all of my local videos stored on my My Cloud (which doesn’t have the CPU horsepower to run PMS).
Do I need an OTA antenna for each TV, or can I use 1 for the whole house?
The live channel don’t come from Plex. Plex is only relaying them from the tuner to your Plex clients.
Therefore you need a tuner device (or several of them) which can provide the number of parallel streams you need in your household. There are models with 1, 2 , 4 or even 8 tuners on the market.
The HDhomeruns usually have 2 or 4 tuners. Take a look into the technical data.
Keep in mind that you also need an extra tuner if you want to record a channel while you watch a different channel.
You should check first, which channels are available OTA in your area. (And which are unprotected/unencrypted). Plex won’t stream protected channels.
https://support.plex.tv/hc/en-us/articles/115007689648-Watching-Live-TV
https://support.plex.tv/hc/en-us/articles/225877347
If I buy a tuner box with 4 tuners in it (1 more than the number of TVs I have), is that enough for my configuration? If so, how do I get the tuner output to the remote TVs?
@lmorgan80 said:
If I buy a tuner box with 4 tuners in it (1 more than the number of TVs I have), is that enough for my configuration?
Only you can know if you want to record more than one channel 
If so, how do I get the tuner output to the remote TVs?
Each TV needs a Plex client.
The Plex client requests the stream from the Plex Server.
The Plex Server fetches the stream from the tuner box.
i.e. all data go over your home network, preferably ethernet wire.
I personally don’t recommend to rely on WiFi for “big screen” devices.
The Plex Server fetches the stream from the tuner box.
Does mean that I need the digital tuner connected to the PC running PMS?
@lmorgan80 said:
Does mean that I need the digital tuner connected to the PC running PMS?
Yes, there are USB device or internal tuner cards.
Or they get connected to your network.
The recommended HDHomerun devices connect to your network, for instance.
