DD-A500GX Hum/Buzz background noise

[qanda]This thread is about the Lite-On DD-A500GX - DVD recorder. Click here to see full specs[/qanda]Hello,

I have a Lite-On DD-A500GX and it’s connected to my TV with both an RF cable and an RCA cable.

I have the outside TV coax cable going into the DD-A500GX.

To access the DVD menu and record, etc. I switch the TV to AV mode.

When watching normal TV (in TV mode), there is no hum/buzz noise.

When watching and recording TV off the AV mode (DD-A500GX), I get a hum/buzz noise.

Both the DD-A500GX and TV are plugged into the same power outlet.

How can I remove this annoying sound?

Thanks.