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
Purpose. The CU-4-1500 is used as a 4:1 (200 ohm unbalanced load to 50 ohm unbalanced source) broadband transformer for 50 ohm coax cable rated at at 1500 PEP into 200 ohms unbalanced load from 1.8-61 MHz. Excellent for 31-33, 41 and 43 foot multi-band verticals and also slopers (51', 85' or 119" work great) made by S9, ZeroFive, MFJ and DX Engineering and Palomar Engineers vertical antennas
USE: The top connector is for the 200 ohm unbalanced output, and the side connector is for a ground rod, counterpoise or radial connection.The SO-239 input connector shield/ground is shared with the ground connector.
For best results use a feed line choke between the CU-4-1500 and the coax input to isolate the coax from becoming part of the antenna. Our Maxi-Choker (MC-1-3000) is an excellent companion for this unun.
This Unun is a very efficient match for many 43 and 31-33 foot multi-band verticals including the S9, ZeroFive, MFJ and DX Engineering vertical antennas.
The CU-4-1500 is also useful for end fed OCF antennas utilizing a 4:1 unun and a coax feed line choke to set the antenna length for the "short" side of the OCF.
CU-4-5000 is in a 4" x 4" x 2" NEMA enclosure and weighs 3 pounds and is specified for 1.8-31 MHz - rated at 5KW PEP
CU-4-5000HD is in a 4" x 4" x 4" NEMA enclosure, contains 50% more ferrite cores then the 5000 and weighs 4 pounds and is specified for 1.8-31 MHz - rated at 4KW continuous duty, 5K+ PEP. The HD version of this unun is CUSTOM MADE PER ORDER - PLEASE ALLOW 2 WEEKS FOR MANUFACTURING PRIOR TO SHIPMENT.
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).