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
Broadband, Non-Inductive Termination Resistor load used on many terminated antenna types such as Terminated Vee (see picture), T2FD, Broadband Terminated Dipole (BBTD), Rhombics, V-Beams and others
Resistive Value: 400 ohms (+/- 10%)
SSB (25% duty cycle) rating in Watts: 600
CW/FT8 (50% duty cycle) in watts: 300
Length (tip to tip) Inches: 11 1/4"
Width inches: 2 1/4"
Inductance < 20 nH (1-61 MHz)Internal Resistance Wattage: 150 watts
Antenna Note: For terminated V antenna shown, use a 16:1 + 1:1 hybrid transformer to match the 50 ohms to 800 (400 + 400) in the antenna "legs"
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).