The RFI generator kit includes 2 ring filters with 3 inch inside diameter for 2 or more turns of AC/DC generator cable at generator and another 2 or more turns through center at the end of the generator cable near the powered device. The filter near the generator isolates generator power cable and prevents it from acting as an RFI antenna (generator source) and the filter near the powered device prevents the powered device from using the generator cable as an RFI antenna.
Use 2 or more turns through the filter for higher RFI suppression than a single turn (2 turns is 4 times the suppression as 1 turn, 3 turns is 9 times a single turn, etc.)
If you have a generator cable less than 1/2" diameter, consider the RFI-GEN-1 generator filter with a 1" inside diameter.
Note: generator cable not included.
AM broadcast transmits on a low frequency with large antennas. Consequently it takes a large antenna to receive the signals. Typical “antennas” are AC house wiring, phone lines, long satellite or cable TV cables, DSL/CAT5 lines running between rooms, etc. The device wires that connect to these “antennas” need to be choked with as many turns through the ferrite as possible. Some installation examples are shown below on this page.
For AC/ DC power cords and coax cables the F240-77 (2.4″ OD, 1.4″ ID) “Donut” toroid is the most popular. Also available are smaller toroid donuts and Mix 77 beads. Shown below is a graph with 8, 10, and 12 turns through the toroid – obviously more turns has higher choking impedance. Mix 77 toroid products are HERE and Mix 77 small beads (for small wires) are HERE
F240-77 Turns Comparison from .1 – 8.1 Mhz
Shown below is a graph of frequency response verses choking magnitude for a F240-77 in the AM Broadcast band for a 12 turn coil around the toroid. (Same info as above but different frequency range).
F240-77 Choking Impedance in AM Broadcast Band
Typical Installations for Donut/Ring Toroids
 AC Cable on F-240 Toroid – 6 turns |
 Ethernet Cable on F-240 Toroid – 7 turns |
 Audio or Mic cable on F240- 12 turns |
Extra Mix 75 Snap On Beads HERE – VERY effective for AM Broadcast RFI