Lightweight Choke Balun

I like to use random wire antennas. My favorite is a 29.5′ antenna with a 17′ counterpoise. I usually use a 5:1 (Chameleon) or a 9:1 (homemade UnUn with it. I have noticed with either combination, some stray RF finds its way back to the radio and me. To combat this, I have a Chameleon Choke balun which is nice but it is rather clunky and uses RG-8X coax. There are times when I am operating QRP, I use RG-316. So I decided to see if I could make a Choke balun using RG-316.

For a toroid, I found a FT114-31 from KF7P Metalwerks. These are rather small.

The toroid I believe cost about 3 bucks plus shipping. I had a 3′ RG-316 jumper with BNC connectors on each end. With a little bit of fiddling, I got 6 turns through the toroid without having to cut a connector. The next step was to straighten out the turns and set them in hot glue. I also applied a ty-wrap at turns 1 and 6.

Hot glue is never an easy medium; this time I managed to keep it off of me. Even though it is messy looking the turns are secure. Toroids are generally brittle and can easily break. I am not always gentle with my gear so I decided to first wrap the toroid in coax seal or “elephant snot”. This will seal out the weather and provide a little bit of a cushion. After putting it on I molded it to the toroid.

Because this stuff is very sticky, I then wrapped it in Scotch 88 electrical tape.

The whole thing weighs in at 3 ounces and should handle somewhere up to 70 watts. It ain’t pretty, but I have less than 10 bucks rolled into it. I will be taking it out this weekend to a park to try it out. I to hear you out there. 73’s Scott

UPDATE 08/16/2022

Today I managed to get into town and buy some wire for my choke project. While there, I bought some heat shrink tubing for my first project. The heat shrink cost more than the little box I had for my second choke. Here is the revised choke with the new heat shrink along with the new choke.

The new choke is made with 16 ga wire, I could’ve and probably should’ve used 18 ga. The toroid is a FT114-31 and it is wrapped 6 turns. the toroid is secured to the bottom of the box with hot glue. Here is a picture before I put the lid on.

Here is the final product.

The box weighs about half an once more than the coax choke. Of the two, I prefer the box, mainly because the toroid is wrapped with primary wire and not coax. It’s a little easier to wrap and looks neater. More than likely, both will perform about the same. For my next outing, I will have an antenna totally made by me. 73 de Scott

6 thoughts on “Lightweight Choke Balun”

    1. Tnx Marshall. This was a down and dirty project. I may built another one in a little box that I have. I need to run into town and buy some insulated wire first.

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  1. Question for you Scott; how do you deploy your counterpoise?

    Once my wife’s kidneys improve and she can get off dialysis we are moving from Florida to a condo in the NC mountains. I’m not allowed to mount anything outside or on the exterior walls of the condo. So getting an HF antenna up is going to be tricky.

    It is an upstairs unit and I’m thinking that I can open a window on one side of the condo and run a 29′ wire along the outside wall and secure it at a window on the other side of the condo. I think I can just drop the counterpoise out the window and it won’t reach the ground. If I use 26 gauge stealth wire then hopefully no one will notice it. It will be on the back side of the condo and the woods will be about 15′ to 20′ away so traffic back there will be limited and I should be okay. Just wondering about a 17′ vertical counterpoise and if you have any experience deploying like that.

    Thanks.

    Marshall
    W4MKH

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  2. Hello Marshall. A counterpoise need not touch the ground. In fact, many use elevated counterpoises. I would suggest you try it. Something else to consider is if you have any metal railing on your condo balcony. That may give you enough of a ground to get a good signal out. You could also try a wire dipole on the upper bands. Hang to apex at the window and use the 26 ga stealth wire. Paint the wire to match the condo and spread them out as far as you can. One other thing to try would be a mag-loop antenna. One last thing. Go to the SGC website and download their stealth antenna book. You can run a verticle loop inside the condo. I hope this helps.

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