1:1 Baluns/Ununs/Chokes

Ferrite Ring Combo Pack, FT240 - 1.4" ID, 10 Rings - Mix 31(4), 61(3), 75(3), RFI Range .15-2000 MHz

SKU FRCP-240-10
$119.95
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Ferrite Ring Combo Pack, FT240 - 1.4" ID, 10 Rings - Mix 31(4), 61(3), 75(3), RFI Range .15-2000 MHz
Product Details
Brand: Palomar Engineers
UPC: Does not apply
MPN: FRCP-240-10
Type: NEW
Country/Region of Manufacture: United States

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

Individually wrapped and labeled with effective RFI frequency range for easy identification

The ring toroids are useful for AC/DC common mode choking with multiple turns as shown below

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AC Cable on F-240 Toroid – 7 turns

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DC Cable on F240 – 4 turns

The ring toroids can also be used on coax or signal lines as shown below:

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RG58 12 turns on FT240

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Ethernet Cable on F-240 Toroid – 7 turns

For RFI/EMI wrap as many turns as possible (usually 6-12) for higher choking (under 30 MHz). For over 25-100 MHz, 1-3 turns om Mix 61 is usually sufficient. Chokes can also be cascaded in series to offer a broader frequency range.

HF 1-61 MHz coax feed line common mode chokes

1:1 feed line Chokes (also known as feed line current chokes, common mode chokes, line isolators, current mode chokes, and 1:1 baluns/ununs) are available in kit form or assembled form in a weatherproof Current Unun and Balun Enclosure which we call a CUBE™. All 1:1 chokes are ferrite based and are designed for 50 ohm coaxial cable input and 50 ohm output. 1:1 Ferrite toroidal or bead chokes have a higher choking impedance than our popular Sleeve Chokes and various models are available for specific frequency ranges and power levels.

1:1 Chokes are useful for choking common mode currents that may flow on the exterior of the coax cable shield while allowing the signals on the interior of the shield and the center conductor to flow unaffected and keeping the common mode current on the antenna. They isolate the coax shield and prevent it from becoming part of the antenna system.  

1:1 Chokes are useful between balanced lines for center fed dipoles at their fundamental frequency (468/f (MHz), beam antennas with a 50 ohm balanced driven element, G5RV, loops, yagis, NVIS antennas, mobile installations, portable antennas and anywhere common mode current (or RFI) is a problem.  They are also helpful between transmitter and linear amplifier or between linear amp and antenna tuner or as isolation chokes where higher choking impedance is needed (in the range of 2K-7K ohms). 

1:1 Chokes are also very useful as feed line current chokes at the “radio end” of the antenna (we call them coax noise filters) where they choke/filter common mode current induced onto the coax shield from radiated waves (from your antenna, and other sources such as DSL routers, computer devices, plasma TVs, etc. originating in your house or your neighbor’s house).  For RFI issues see RFI/EMI Solutions for general use or for specific radios and devices.  

For best results we recommend a 1:1 choke at the “antenna end” of the coax and a coax noise filter at the “radio end” of the coax. (A side benefit is a reduction in noise level caused by common mode currents). 1:1 chokes are also available as Sleeve Chokes (Slip on or Snap on) for ease of installation and light weight on the antenna.