The other week, a friend of mine Rob VK2GOM shared a photo of a 1:1 current balun he had built to try and reduce some local noise issues he had at his home. His device had improved his experience. He chose 17 turns and the FT240-43 core based on info from this website Have a read of that page for a better understanding.
I have a fair bit of suburban noise living in a small block in middle suburbia, my antenna runs along a fence line adjacent to two houses, plus this house is full of gadgets. I also sometimes get some RF in the shack, just because of the less than ideal setup and operation I have. So, for a couple of dollars and a small bit of time, i decided to build up what Rob had made and see if it helped.
The device uses 5 items. (you may have may in your bits box)
- An FT240-43 Toroid from Minikits $8.90
- 2x SO-239 Flange mount from Minikits $3.90 each
- RG-58 Coax from Minikits $1.25 per meter
- A suitable Box Jaycar HB6246 $12.95
- Three cable ties
- Some Nuts/Bolts/washers/Solder lugs
So over the last couple of weeks, when time permitted I had made it up.
Take the coax (2-3m, i didn’t actually measure how much I used) and cable tie a short coax tail at the base of the toroid to start the winding. The configuration I have is 8 turns per side, with a cross over, 17 turns all up. When you get to the top of side one, cable tie this half to keep it tight and even. Cross over and repeat on the other side. Once you get back to the top, cut your top temporary cable tie holder and replace with a new one on the end winding.
Then drill up the Box, fit the SO239’s, solder it up and you are done.
Its made a small improvement on local noise. Doesn’t appear to have any negative effects It was easy to make and now is inline with my radio.