OK, so this is usually referred to as a booster join-tenna / polyswitch in that it can merge two discrete inputs to generally 2 outputs.
Behind the wall there are connections for OTA, and perhaps park cable or external Sat. connection. There is also another feed to a (bedroom?) TV.
Amp ON enables the OTA booster. Off allows throughput of cable or Sat. to both TVs.
*The TV near this plate connects to the F-connector via coax, to the TVs F-coax (NTSC) connection. Other HD items may be using HDMI.
You'll need to, through ea. TVs setup menu, select source, TV/ OTA As opposed to HDMI. Then run a channel scan for each of these modes of operation (OTA or cable, source material).
Best of luck
Wingard type equivalent manual: (*May have optional 12VDC lighter plug) Attached Files 2451486.pdf
(340.7 KB, 8 views)
DRV Suites ES-38RSSA #9679
GM Denali 3500HD-Max 4x, CC, 8' DRW
EZGo-TXT, Yamaha-G22E, CC Precedent