64:1 Unun for 80M EFHW

Tue, 13 May 2025 00:00:00 +0000

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.

Fixing the 4:1 Unun

Tue, 04 Mar 2025 00:00:00 +0000

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.

4:1 unun corrected

Unun on John Flinchbaugh KD3EE

64:1 Unun for 80M EFHW

Fixing the 4:1 Unun