The Ferrite Ring Combo Pack is a convenient solution for troubleshooting RFI/EMI from unknown frequencies or multiple frequencies that require multiple suppression mixes. Included in this combo pack are ten 2.4″ OD/1.4″ ID ring toroids as follows:
Mix 75 effective from .15-10 MHz including AM Broadcast band – quantity: 3
Mix 31 effective from 1-300 MHz for general purpose – quantity: 4
Mix 61 effective from 200-2000 MHz for cell phone, WIFI, HDTV, Cable TV interference – quantity: 3
Exercise Equipment RFI Kits
Does the operation of a treadmill or your exercise equipment wipe out your radio receiver reception? We have heard cases where the treadmill from a neighbor’s house wiped out the ham radio receiver reception from 2-30 Mhz! The treadmill source was finally isolated to a variable speed motor power supply that was injecting RFI into the AC wiring of the house and the AC wiring was acting as a transmitting antenna broadcasting the signal to the entire neighborhood. The case was difficult to track down since the broadband RFI interference only occurred at 7-8 pm each nite when the neighbor used the treadmill. As with all RFI cases the sequence is similar: Find the Source, Choke the Path, Protect the Victim.
Once the source was identified, a simple solution was to choke off the transmitting antenna with a AC line choke shown below which eliminated the interference problem to the ham receiver:
Testimonials
F400-31 AC Power Cord Choke completely cured the RFI problem I had with my wife’s treadmill. Now I can hear the weak signals!
The ring toroids are useful for AC/DC common mode choking with multiple turns as shown below
 AC Cable on F-240 Toroid – 7 turns |
 DC Cable on F240 – 4 turns |
The ring toroids can also be used on coax or signal lines as shown below:
 RG58 12 turns on FT240 |
 Ethernet Cable on F-240 Toroid – 7 turns |
For RFI/EMI wrap as many turns as possible for higher choking (under 30 mHz).