What frequency range do you want to reduce? For HF 2-30Mhz range wrapping 8 to 10 turns of most cables like AC power, speaker, Ethernet, RG-58 coax, etc, around an FT-240-31 core does a good job. The very best price I've found on these is here:
https://proaudioeng.com/fair-rite-2-4″-toroid-core/
For smaller cables like USB, about 5 turns around one of these works well from about 2 to 30MHz:
https://proaudioeng.com/fair-rite-0-4″id-ferrite-snap-core/
For VHF/UHF about three of these snapped over a small dia cable works well:
2x31-3951p2 - Amidon and for large dia cables:
2X43-351P2 - Amidon
If you have a big problem its best to identify what the source is and what its fundamental frequency is. Sometimes a power supply switching at 30KHz will cause problems throughout the HF range and using a different mix ferrite like 77 or ?? will give better results.
For serious noise problems it might be good to call Bob at Palomar Engineering and discuss your noise problem with him. They sell the same ferrites as anyone else and at a higher price, but if you need an experienced person to help diagnose and recommend a particular ferrite its worth the extra $$.
prcguy
I would like to wrap my USB cables and perhaps antenna cables with toroids to reduce noise.
What is the appropriate type and number of toroids to effectively reduce interference?
Is it EMI suppression that is need or?
Make, model number, and if possible - where to get them please.