About a year ago, I bought a few end fed half wave antenna kits from the QRPGuys. The No Tune End Fed Half Wave is of those that I got out of curiosity. The fact that there is no tuner required seemed intriguing. Basically, I’m skeptical so I’m going to build this one and try it out at home to see if it operates well.
Like I said before, inspiration struck while I was on the roof a bit ago, so I’ve also mounted enough wire for 80m above my house. Purportedly, you can operate an 80m through 10m without a tuner if your wire is made for 80m.
The QRPGuys No Tune End Fed Half Wave kit includes a board, a bnc, a 150pF capacitor, some stainless hardware, and a mix 43 toroid with magnet wire. It’s a pretty straightforward project. The kit doesn’t ship with instructions, but they are provided on the website which I like so I can compare the antennas before I make a purchase.
I’ve decided to build the kit in the order as described in the documentation. So, after mounting the bnc, the capacitor, and the stainless hardware, it was time for building the final component: winding the 49:1 unun.
If you’ve never wound a toroid, don’t worry. It’s not difficult as long as you can count. The instructions provided on the kit website are well done.
There’s just a couple of things to remember about winding toroids: the number of turns that go through the center of the toroid are the ones that go toward the count. Personally, I’ve always taken a photo of my wrapped toroids in order to count the turns.
Also, the magnet wire insulation must be removed in order to connect it to the board. Some insulation can be soldered off or burned off with a lighter while others must be scraped off with something sharp.
Following the instructions carefully gave me a perfectly wound toroid. The QRPGuys method of scraping and twisting the magnet wire yielded beautiful results.
After soldering the wound toroid into place, I hooked it up to my nanoVNA. Since I strung up 140 feet of wire, it resonated at 3.14 instead of nearer to 3.5. Carefully trimming sections of wire away led me to 125 feet of wire left (as the kit said to cut for 80m) with an SWR of 1.35 at 3.5.
It is resonant where it should be, but really only usable on 80m, 20m, 12m, and 10m without a tuner of any kind. In the CW portion of the band, it is above 3:1 on 40m and 30m, which is disappointing. So, next project will be to construct a touch-up, L-match tuner.
On air tests revealed that it does get out. I have made one contact so far. Justin, KC0MYY in Minnesota and I had a brief but nice chat in spite of the CQWW contest going on this weekend, exchanging 579 and 559 among other bits of info.
I’m glad to have an antenna at home and with a bit more tweaking, I believe that I can operate on all the bands that I want.
Amateur Radio Station WB0ISG 