I have an EFHW wound according to Steve Ellingtons instructions.
What I've learned:
Start with a wire 135 feet or longer, I also wrap at least another 5 or 10 feet back around the far end for good measure.
You can always cut, not add.
Tune for low SWR around 3.5 MHz. Since you left the wire real long, your going to be cutting little by little.
Your minimum SWR on 80m probably will start around 3.2-3.3MHz before you start cutting.
Get a Nanovnh, it makes it so much easier.
http://www.randl.com/shop/catalog/product_info.php?cPath=8620&products_id=75145Next, download the program NanoVNA-Saver its free, screw working off that little 4 inch screen,
Makes pretty SWR graphs of your EFHW like this:
Info on NanoVNA-Saver Program I then setup an up close scan on 80m from 2-5Mhz, do some more cutting and get 80m near but not exceeding 3.5 MHz at minimum SWR, then check all the other bands up close, individually as you go.
Best $60 I ever spent.
This url gives you a chart as a goal to where your minimum SWRs should fall for each band:
https://www.electronics-notes.com/articles/antennas-propagation/end-fed-wire-antenna/multiband-end-fed-half-wave-efhw-antenna.php