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