I have found mine useful, it is a low cost RFI and EMI detector I bought on Amazon. I used it when building a custom streamer to test the shielding. I also use it to test components and power cables. They all emit something, but it is useful in finding items that are emitting more than their fair share.
Opinions on A/C Noise Meter EMI Testers
Is there a consensus as to the usefulness of these devices?
Thanks!