Yes there is a grounding screw on the back of the AV Receiver. One thing to keep in mind if I replace the Joey 4k with a wireless Joey I get dead silence. It is 100 percent the coax that is the cause of the noise but why its louder in the evening is beyond me.
Another solution is a humbucker. It's what we used when I worked in broadcast TV. (Not the guitar pick up.) I think ADC still makes one. HUM-1? It has a transformer in the ground path to effectively isolate the hum. It uses a BNC connector so you'd need BNC to F adaptors.
Maybe someone makes a video isolator that has F connectors.
Another solution is a humbucker. It's what we used when I worked in broadcast TV. (Not the guitar pick up.) I think ADC still makes one. HUM-1? It has a transformer in the ground path to effectively isolate the hum. It uses a BNC connector so you'd need BNC to F adaptors.
Maybe someone makes a video isolator that has F connectors.