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Time to reduce the annoying RF sources that are picked up in your radio, or cause havoc with interconnecting shack equipment.  Our choke kits provide the ferrite, the cable, and the know-how to stop or dramatically reduce RFI on coax, USB cables, and ethernet cables.

If you own an antenna fed with coax, you need RF chokes on the feedline!  Using a choke/balun with adequate RF choking impedance will improve the performance of your antenna, prevent pattern distortion, and prevent RF coming down the feedline, which can cause RFI.  Many antenna manufacturers simply do not provide an adequate balun with their product, or one that has no choking function at all.  Long coax runs can benefit from additional chokes near the shack as it cuts down on receive noise.  Other types of cables benefit in the same ways a coax.  USB and ethernet easily pick up radiated RF energy and conduct it right into places it does not belong.  Put an end to annoying RF related problems with our choke kits.

Check out our TECH page for lots of information on ferrite material and how to properly use it.  



Time to reduce the noise in your shack!  Most baluns that come with antennas these days do not provide enough choking impedance. Replace that ineffective balun that came with your antenna, or add an Excellent Choke where your coax comes in the building. The Excellent Choke has over 4000 ohms of choking impedance at 14 MHz!  Every HF installation should have a high impedance choke on all cables leaving the tower and at the building entrance.  W1HIS’s Excellent Choke is an affordable solution. Avoid paying higher prices by sourcing materials from different vendors and paying multiple shipping charges. Get all the parts from one source!

  1. High performance, high choking impedance stops common mode on coax shield.

  2. Reduce RF in the shack problems (hot mic, feedback, etc.).

  3. Eliminate RFI issues around your house (TV, radio, computer, stereo, etc.).

  4. Lower your receive noise floor.

  5. Can be used at feedpoint of your antenna (replacing balun that came with your antenna), AND/OR at output of radio gear.

  6. RG 142 coax: Teflon dielectric, silver plated copper clad steel conductor, and TWO silver plated braid shields.

  7. Suitable for legal limit RF levels.

Kit includes four Mix 31 ferrite beads, 4 feet of Mil Spec RG 142 coax, and two silver plated teflon PL259 connectors and reducer bushings.  Requires soldering PL259‘s onto the cable; comes with winding instructions.


W1HIS “Excellent choke!” kit

Ferrite choke kits for coax, USB, and ethernet

Click on chart to enlarge

Choke is approx. 20” long.

I put one of these excellent choke kits at my transceiver and another "pretty good" choke at the feedpoint of my G5RV Jr. It knocked a good 2 or 3 s-units off of the "band noise" I was experiencing. The product is well made and easy to put together, and the ferrite components are top-notch. I will be ordering more.


User Reviews:  What are other hams saying about these products?



                            RF CHOKES
User Reviews:  What are other hams saying about these products?

Love the big mix 31 Ferrite Beads...They really do the trick.




Made on a Mac

Love Big Mix 31 works great !! Made a big difference on my transceiver.




Electrical tape

Liquid electrical tape

Related Accessories

Zip ties


$38.95 $31.16

Purchased the "Biggest Clamp-On" 220-31 for common mode rejection.  Both the price and service were excellent; Very competitive. 




Models Available:

Excellent choke, kit form

Picked up an excellent choke kit for the feedline and biggest clamp on for the power cable.  They work great, shipped fast, Thanks!




These mix 31 snap on beads that Chris sells are the best.  He packs them up well and shipping is fast!  The largest Mix 31 snap on bead can fit 4 turns of LMR400 Flex through it no problem.  Perfect for getting rid of my 10 meter common mode interference.  Prices are also better than all of the other suppliers I checked.




I bought 4 of the mix 31 beads to make the W1HIS “excellent choke”.  If you lube the coax slightly you can get 3 turns of RG8X through these

.505” beads.  I was shocked at how much this arrangement reduced the noise floor in my receiver...6dB or more on 40 meters.  I’ll be ordering more to experiment with.  KF7P does an excellent job of packing and ships very quickly,..highly recommended.




I have successfully stopped all RFI from my shack with these snap on chokes.  They are the best I’ve seen, and Chris has the best prices I’ve found on these essential parts for the shack.  Plus great packing and fast shipping.  Highly recommended.




Looking for ferrite beads, toroids, and clamp-on units?  Visit our ferrite page.

Utilizing high performance RG-400 coax, these choke can provide thousands of ohms of choking impedance (depending on frequency desired and number of winding turns).  Choke kit is a KIT (U-wind-it, don’t sweat) and comes with connectors factory installed for easy installation.  Suitable for all HF bands 160m to 10m; choke can be built to your target frequency for maximum choking ability to solve your RFI issues.

Remember that RG400 is high end coax:  TWO silver plated braid shields, teflon dielectric, and silver plated center conductor.  This type of coax is absolutely needed as it can handle the tight radius bends around the toroids AND high power.  The UHF connectors are a perfect match:  Silver plated brass, teflon insulation, soldered in place and heavy adhesive shrink tube seal.  Easily handles legal limit power.

Includes  6’ coax assembly,  2.4” OD toroid, zip ties, and winding instructions.

Coax choke kits




Models Available:

RG-400 choke kit mix 31 toroid, 2.4” OD toroid (160-20m)

RG-400 choke kit mix 43 toroid,  2.4” OD toroid (40-6m)

Ever had trouble with RF knocking out your computer or the connection between the radio, computer, or other computer controlled interfaces?  Stop that RFI with our USB cable choke!  Like all of our products, cable is USB 3.0, made of high quality 28 and 24 gauge copper wire, with a foil shield and braid shield.  One end is A male, other is A female for easy connection into your existing shack layout with minimal wire related messes.

Comes with:  6’ USB cable,  2.4” OD toroid, zip ties, and winding instructions. 

USB cable choke kit




Models Available:

USB choke kit, mix 31 toroid (160-20m)

USB choke kit, mix 43 toroid (40-6m)

Ethernet...a blessing and a curse (especially for hams!)  Ethernet is a notorious polluter of the radio spectrum, especially if power over ethernet (POE) is used, and difficult to knock down.  Ethernet choke kits are specially designed by a team of RF professionals and thoroughly tested on gig speed internet without interrupting, slowing, or loss of signal.  Flat cat6 ethernet cable is the key, which handles the tight radius around the ferrite without disturbing the pair geometry.  Achieving 25+dB of attenuation is easy by selecting the right ferrite mix and following the winding guidelines.  Multiple chokes can be run in series using different mixes to cover more radio spectrum and increase attenuation.  Comes with 5’ cat6 cable, ferrite, zip ties, and female to female inline coupler to make installing the choke super quick. 

Ethernet cable choke kit




Models Available:

Ethernet choke kit, mix 31 toroid (160-20m)

Ethernet choke kit, mix 43 toroid (40-6m)

RG400 Coax choke

USB cable choke

Ethernet choke

PL259’s come installed

Comes with line coupler

Similar to the choke kit above but containerized for easier outdoor installation.  Utilizing high performance RG-400 coax and comes in a weatherproof box for outdoor use.  Choke is assembled, tested and ready to be plugged into an existing installation with so-239 connectors on both ends.  Suitable for all HF bands 160m to 10m; built to provide 4000-5000 ohms of choking impedance through the HF bands with mix 31 toroid.

Remember that RG400 is high end coax:  TWO silver plated braid shields, teflon dielectric, and silver plated center conductor.  This type of coax is absolutely needed as it can handle the tight radius bends around the toroids AND high power.  Easily handles legal limit power. 

Both the low power and legal limit versions come with an internal gas discharge tube and bleeder resistor.  The 1600v rated gas discharge tube shunts harmful power surges to ground, and bleeder resistor harmlessly provides a drain path for static to ground, functioning continuously whether antenna is in use or not.  NOTE: Product must be properly grounded! This is NOT a substitute for proper bonding, grounding, or installed lightning arrestors; it does offer additional protection at the point of installation. 

Now available:  Mounting bracket to attach to any round member such as aluminum antenna boom, tower leg, etc.  Made from laser cut aluminum, comes with stainless holes clamps, ground tab (which connects ground stud on box to mounting bracket), and hardware. 

Common mode, unbalanced HF Choke








Models Available:

Common mode HF choke (in box), mix 31 toroid, (160m-10m), with surge suppressor. 200w.

Common mode HF choke (in box), mix 31 toroid, (160-10m), with surge suppressor. 1500w.

Mounting bracket for 2” tubing (antenna boom, etc.)

Mounting bracket for 1.25”-1.5” tubing (Rohn 25, 45, 55).

Questions? Email Chris@KF7P.commailto:Chris@KF7P.comshapeimage_60_link_0