Saturday, August 18, 2018

QRP Guys vertical antenna

Thursday evening, I came home to a delightful surprise. My son had mowed the lawn while I was at work. That gave me some unexpected free time and I used it to build the QRP Guys 3 band vertical antenna that I had recently purchased.

Today I got the chance to deploy it and check it out.  I used my 31' Jackite pole as a support, which was definitely overkill. I ordered a 20' fiberglass crappie pole from Sportsman's Warehouse for $20 - but it won't get here until next week. As per the QRP Guys instruction manual, I checked eBay for "17' fiberglass fishing pole", but came up blank.

Anyway, getting back to the subject at hand, this is what it looked like.

I hooked up my little Autek antenna analyzer, tuned it to 14.060 MHz and checked the SWR and found it to be 1.5:1.  Following the instructions, I cut a 3" section off, thinking I could get the SWR even lower, but it ended up increasing instead of decreasing!  So I replaced it with another 17' piece of wire and am going to let it go at that. In any case, the KX3's autotuner brought the match to 1:1 in less than half a second. The same held true for 30 and 40 Meters.

This is a close up of the actual circuit board portion of the kit.

After all was said and done, I secured the toroids with the provided wire ties. To secure the matching portion to the fishing pole, I am going to end up using two pieces of gardener's Velcro tape that I keep in my backpack. When not securing the board to the pole, the Velcro tape will keep the antenna and radial wire bundles neatly wound.  Here's a view of the antenna looking back towards my operating position.

The circuit board was a piece of cake to build. Even the toroids were no big deal. After all the toroids I've wound over the years, I don't even think twice when I have to wind some. The hard part for me was seeing! The "close" portion of my bifocals are OK for reading; but are useless for real close work like soldering. I took Bob W3BBO's advice and bought a cheapie pair of grocery store "readers". In my case, I chose the +1.5 magnification variety. I put those on and no problem! Those are going to be a tremendous help in kit building projects, as my eyes are nowhere where they used to be.

Tomorrow's weather is "iffy" at best for my neck of the woods. There's a 50/50 chance of showers the entire day. I may end up working the Hunt from the backyard, losing the water bonus points. My reasoning is that I have that nice, big umbrella that you can see in the third picture. That will be a real boon should it start to rain. And it it should start raining really hard then I can always finish the Hunt from the basement shack, if I really have to.

I have my fingers crossed, hoping it ends up being a blown forecast and that I'll wake up to sunny skies tomorrow morning that end up lasting for the whole day.

72 de Larry W2LJ
QRP - When you care to send the very least!


  1. The improved matching you were looking for has the answer in the radials, in all likelihood. You should try experimenting with fully raised, slightly sloping radials, maybe with 'gull wings' (search online) for fine-tuning, rather then droop-to-the-ground wires.

    I also suspect the position of that radial connection point could cause imbalance issues to one degree or another.

    We all do it, but remember that with an uncertain antenna, folding back the wire and taping is always less risky than cutting it!

  2. (After looking at the images again)

    It would also be an idea to test the antenna away from steel-infested garden furniture. Try it in an open field.

  3. (After reading the manual, with a bit of skepticism as to what can be expected)

    Quoting fromthe manual, it seems your matching was better than even the maker expects, which anyway is not good:

    ..."folding back the wire for lowest SWR, ~2:1. When finished fold back the driven element on itself, and secure it. Our experience is that after tuning it for 20m, the antenna will be ~2:1 on the other two bands with the proper switch settings. You may need
    to squeeze or expand the turns on L1 for 30m and L2 for 40m to obtain these results.
    Do not change the length of the radiating element."

    Personally, I can't see where the success or purpose is for an antenna where:

    "If you want the SWR to be less or broader coverage, just use a
    tuner for the whole band."

    Eh? Might as well just carry different monoband verticals in your pocket, then!
    We have found