Basic RF Choke

RF in the shack can make operating difficult and in some cases impossible. A RF Choke can help keep the rf currents from flowing on the outer braid of the coax. Many Hams just use a bunch of ferrites close to the feed point. Another method is the open air choke. These are easy to build and cheap.

As a project, I wanted to make an open air choke to use for portable operations. Also,a friend of mine is having some issues with rf and I wanted to test a choke that is constructed of 25′ of 50 coax. BNC connectors will be placed on the ends for quick connecting and disconnecting. I made a second version that I have used in the past on 2 meters. It is constructed the same way but uses 40″ of 50 ohm coax.

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For the HF choke 25′ of RG-58 will be used. For the 2m version I use 40″.
11″ of 1 1/4″ conduit is used as the form for the HF Choke. 4″ is used for the 2m version. Drill a hole slightly bigger than your coax.
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Insert the coax through the hole the is drill close to the end. Tightly coil the coax around the form. Once you have the coax through the holes in the end of the pipe, use a tie wrap to keep the coax in place.
I am using 3D printed caps with BNC connector at the end of the pipe. This should make it easy to connect and disconnect the choke.
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After the coax is connected to the connector the caps were hot glued in place.
I wanted to tape the ends very well to help prevent water penetration. Since this unit is being constructed for testing, I did not water proof it the best.
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2m version of choke.
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Links

https://km4nmp.com/2019/06/22/6m-delta-loop/

https://km4nmp.com/2019/07/14/2m-portable-j-pole-antenna/

https://km4nmp.com/2019/05/04/2m-1-4-wave-ground-plane-antenna/

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2 thoughts on “Basic RF Choke

  1. Never could build a decent one.

    Liked by 1 person

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