2023-05-25 After playing with both the AX1 and the DS-1 antennas, I think I prefer the DS-1 in the pedestrian mobile Context. Performance wise I think they are identical. I've had a number of activations with both in the past few weeks and do not notice any difference in terms of contacts. All my pedestrian mobile has been done on 20 meters to date. The main reason for my preference for the DS-1 is ruggedness. It just seems a bit more robust than the AX1. The AX1 seems designed for fixed use. When I used it on my pedestrian mobile setup I found a tendency to loosen up. The aluminum caps on each end tend to come unscrewed and the whip loosens also. No similar issues with the DS-1. But both are great short compact vertical antennas.
2023-04-18 I started playing with short portable verticals about three years ago. The QRPGuys DS-1 somehow caught my attention. So I ordered and built one. I have trouble with patience so while waiting for it I built my own version of it, using their online instruction sheet as a guide. I had fun with both. I concluded that given that they are very short verticals, they perform well. However compared to almost any other antenna, they are a challenge. Seldom will you connect them up and get a bunch of contacts quickly. They simply are too compromised for that. But having said that, when what they are, very short verticals, is what you need, they are as good as it gets.
After my initial excitement with them both, they went onto the shelf, largely forgotten, with one exception. That was a short term interest in pedestrian mobile. What fun! And a short vertical is almost mandatory if you are going to walk down a trail with a radio on your back making contacts. Suddenly I became very impressed with the capability of those antennas! My log shows about 85 contacts m most POTA activations from park k-4265 here in SE Wisconsin running 10w with the rig on my back driving a modified version of one or the other of the short vertical and dragging a 15' counterpoise wire along behind. I even logged four contacts to Europe, all but one CW. That one was SSB to a station in The Azores. So there is a place for the very short vertical and one can have a lot of fun with them.
Those antennas have been stowed away for a long time now. Then a week or so ago one of the most active activators did an activation with the Elecraft AX1 short vertical with rather impressive results. Then another guy on YouTube I enjoy watching did an activation with an AX1. Sadly, I've "lusted" after that antenna for a long time. In fact the reason I got the QRPGuys one was to try to kill that lust. But alas, that failed and a couple days ago an AX1 came in the mail.
The two pictures above are an attempt to compare the AX1 (left) and the DS1. The whips are identical, measuring just under 47". The AX1 coil is "cuter" than the coil of the DS1. But functionally they are pretty comparable. The AX1 weighs 3.2 oz. whereas the DS1 weighs 3.55 oz. So there is not much physically recommend one over the other. Performance wise, I logged 11 contacts with the DS1 (Not in the pedestrian mobile configuration) and just two with the AX! after I got it yesterday. But I have no reason to expect any difference in on-air performance.
So why should one buy one or the other. The pros for the DS1 is cost. It is much less expensive than the AX1. However there is a labor or assembly cost that should be considered. It is not a difficult build, but it is also not trivial and is certainly easier if you have a drill press and a few other hand tools and are overall handy. The con for the AX1 is cost. But it's pro is that it is ready to go when you take it out of the box. Both are very good "very short" verticals and you can't go wrong with either. Just don't expect the performance of a full sized vertical or a dipole!