Balun

Today I experimented with building a 64:1 unun for an 80-meter EFHW.

My initial attempt involved 3 primary / 24 secondary windings, but I quickly found that this took up too much space on the small toroid I was using.

After some adjustments, I settled on a 2 primary / 16 secondary windings, adding a 100pF capacitor. This configuration was inspired by resources like KM1NDY’s DIY linked EFHW 64:1 antenna guide.

I’m now successfully running my home EFHW antenna on 40 meters without needing a tuner. On 17 meters, the SWR is a bit high, so I engage the tuner for that band.

This setup reminds me a lot of my previous 71-foot random wire antenna with a 9:1 balun. I’m noticing a significant increase in the number of signals I’m receiving, which suggests this new EFHW might be a considerable improvement over my old 107-foot EFRW.

I had followed the these nice directions to build my 4:1 unun to use with a Rybakov and Tactical Delta Loop, but I made a mistake:

• the wires that come from the shield continue in opposite directions around the toroid
• on my bad build, they originally both went the same way side by side.
• the diagram is clear, if you look closely, but the picture is even clearer.

I tested the 4:1 with the tactical delta loop. It consists of:

• the 4:1 unun.
• 2 17-ft telescoping whips up diagonally 90 degrees from each other.
• 25-ft wire connecting the ends of the whips with alligator clips.
• 3d-printed plastic mount to hold it all at the bottom.
• screwdriver stuck through the mount into the ground to hold it up.
• alligator clips to connect the unun to each side of the loop.
• ground spike (screwdriver) wired to the ground side of the loop/unun.
• tuner is required to work 40M-6M. 80M and 160M didn’t want to tune.