The simplest, most cost effective AC power cord noise filter is a ferrite ring installed as shown in the picture (at the appliance AC input) to stop feed line appliance radiation back into the AC power line or into the radio/appliance to suppress common mode power line noise current on the AC power cord or to suppress common mode noise present on the power lines from degrading the performance of the attached device.
Keeps RFI out of appliances like TV, radios, computers, etc and like wise keeps noise generated by electronic devices from feeding the noise back into the AC power line and affecting other devices plugged into the same lines.
These chokes are cheap, easy solution for RFI issues. Just replace your existing power cord with these pre-wound cables and enjoy interference free operation.
Got your own AC power cable that needs a ferrite ring only? The use ACCF-1.4 ring. This ring also works well on switching power supplies (use 1 on AC input and another on the DC output or just order kit RFI-SMPS).