Ceedmon 20 Pieces Clip-on Ferrite Ring Core RFI EMI Noise Suppressor Cable Clip for 3mm/5mm/7mm/9mm/13mm Diameter Cable, Black

Surprisingly useful, and delivered in a timely manner

These are great! Snap them on and done. See my picture for exactly what was in the box, as I'm not sure if it matches the description but seemed pretty close. I've written the sizes on them in the pic if you look close. The 3mm are good for regular car wires, which I used on my headlight wires at the bulb, the larger ones are good for covered cables, as well as smaller wires if you want to try looping them thru a couple times or more. They snap on easily and with a small screwdriver they are easily removed, yet seem to be quite secure when attached. Would buy these again.

I am using these for ham radio transmitter applications. I use digital modes a lot, i.e. FT8. Occasionally I will have an issue where I key up the transmitter and the program goes nuts. Loses its connection to the radio and D to A / A to D converter (Signalink). I suspected the USB connection to the computer was being scrambled. I had bought the Signalink cables for between their TNC and the radio, which contain built-in toroids for RF suppression. But used a plain old USB2 cable I had lying around to save a few bucks. Well, apparently cheaping out burned me. I installed the RF chokes listed here, one on each end of the USB cable (choose an appropriate diameter), and the problems have stopped. I am impressed with the quantity and number of diameters that are include, and that the snaps to close the toroid are openable - so you can reuse these on other devices. Decent quality.

There is a cell tower very close by that was causing a low-level, but still audible interference (when amplified to line level) in my microphone cable. This is despite using a top of the line $50 balanced XLR cable and high quality audio interface / preamp. It took a whopping SEVEN of the cores clipped onto the cable, but I finally got it eliminated by about 99% to the point where it's not a problem. You can see the before and after screenshot. Do note that even after one, it made a significant difference, it's just that each additional one is diminishing returns. Another thing I'll add, is even though this worked, it also required me to use very high quality equipment for the whole rest of the chain. I have cheaper unbalanced audio cables, and a cheaper audio interface (Zoom H6), and with those, the interference is way worse and probably couldn't be eliminated completely even with the ferrite. So if your devices support balanced audio cables, definitely try that too. Tip: Try different placements of the ferrite cores. I found that when placed on the end closes to the microphone or at the middle of the cable, it made almost no difference. But they DID make a big difference when attached as close to the pre-amp as possible.

They worked as stated but they break if you squeeze them to get them to close and snap together. I had a couple break because it was hard to get them to latch properly.