Many thanks to Skip (K4EAK) who shares the following guest post:
The QRPguys DS-1 Portable Antenna Kit
by Skip (K4EAK)
There have been several videos and extended comments lately about the Elecraft AX1 and AX2 antennas, both of which function remarkably well for a small, highly compromised antenna.
For those interested in other, similar designs, especially those hams who find that building the equipment is half the fun, another option to consider is the QRPguys DS-1 antenna.
The DS-1 is similar in concept and design to the AX2. It consists of a base-loading coil, a 46.5-inch collapsible whip, and a plate to attach the antenna to a small tripod. One can also purchase an add-on 40-meter coil. The can be deployed in just a couple minutes and, when collapsed, the longest portion is only 6.5” long, easily fitting in the palm of one’s hand. QRPguys recommends a 16.5′ counterpoise; I use two such wires, usually spread out at a 180-degree angle. I’ve also used it with a clamp-on mount and a car window mount.
Building the antenna is simple and took me less than an hour. After installing a BNC connector into a brass plug and inserting the plug onto a length of PEX tubing, one simply runs the supplied 22AWG wire from inside the tubing, out and around making 22 turns, and then sealing it with a length of heat shrink tubing.
There are really only two aspects of assembly that are slightly more difficult. The first is that it’s necessary to drill and tap two holes for 4-40 screws, which obviously means that (1) one needs a 4-40 tap and (2) one needs to be careful tapping the threads to assure a clean cut. The second is that the heat shrink tubing, at least as supplied in my kit, was grossly oversized, which required some finesse in getting a final product that was at least reasonably aesthetic, to say nothing of accomplishing that without dry roasting my fingertips.
Field testing of the DS-1 shows that it works surprisingly well. The SWR is well below 2.0 across almost all of the 20-meter band and where it is higher than that (the upper end of the voice portion), the KX2 internal tuner can tune it easily. As one would expect, on 40 meters the antenna has a somewhat narrower range, although the KX2 tuner has handled it on all of the frequencies I’ve tested so far (all CW). And it appears to be efficient enough.
I have used it on numerous activations and consistently get to the requisite 10 contacts within 20 minutes or so after getting spotted. After that, the number of contacts depends on the time available, but for those occasions when I have only a 30-minute window for an activation, the antenna is a convenient and practical alternative.
I keep the antenna, the tabletop tripod, and the counterpoise wires in the water bottle pocket of my pack, ready for use whenever I have a few moments for a quick activation.
73 Skip K4EAK
26 thoughts on “Skip recommends the QRPguys DS-1 portable antenna kit!”
I agree with Skip’s post. I built the DS-1 portable antenna a few months ago; it went together well and it works well.
One drawback, though, is that the BNC connector is mechanically sloppy, causing the antenna to wobble when mounted. For this reason, and the allied fear of the antenna breaking at the point of wobble, I have not used this antenna very much. Oh, well.
I built the DS1 a few years ago and have used it on and off throughout that time and always been very pleased with it. There’s a couple little tricks you can do to make the thing a little more mechanically sound if you’re so inclined. Have not really had any issues with it in that regard. I’ve often referred to it as the DIY AX1. The kids not expensive, and I use a mini tripod I had laying around from previous adventures. I’m in the midst of trying to put together a tiny mobile kit, and this along with my TX 500 make a very small package indeed.
You should definitely mention your tricks directly in your post. Others might want to learn from your experiences.
I’m not sure I remember the finer details of the build, as it was at least a couple years ago. I do recall the caps on either end of the pipe were held on by two screws. Increasing that to 3 (or more) definitely removed a bit of wiggle. I suspect a spot of glue might not be amis for the same reason.
I have had success tuning this up across a number of bands, by adjusting the whip length. I’ve been trying to come up with a clever way using marker paint or string to indicate which lengths work best for which bands, and save myself a bit of fiddling around with the tuning when I deploy it. I realize there were always be a bit of fine tuning, but starting off in the right neighborhood is always a good idea. Welcome thoughts.
The “mechanical sloppiness” in the antenna that I mentioned in my original post was due to the BNC coupling (at the bottom of the antenna to the BNC bulhead connector on the mounting plate). Attaching the antenna to the connector resulted in a poor mechanical fit that allowed the antenna to precess when fully extended. I recently inverted the BNC bulkhead connector on the plate, whch reduced the sloppiness but did not eliminate it. I just ordered some low cost BNC connectors hoping for a variety of fit tolerances that might eliminate the sloppiness of the antenna fit to the mounting plate connector (ie, give a tight BNC male to BNC female mechanical connection).
While this antenna remains a nice build and fine performance option, be careful about parts’ fit tolerances to result in a more mechanically sound product.
Construction UPDATE: I ordered some other BNC-BNC bulkwark connectors, got a tight fit to the BNC male connector at the bottom of the antenna, then realized that the “sloppy fit” problem was with that “loose” BNC male connector (supplied with the purchased antenna kit) that forms the bottom of the antenna, and is soldered to the wire of the coil.
Solution: before you construct the antenna and solder the BNC connector in place, test it’s fit to the BNC-BNC bulkwark connector that will be part of the underneath mounting plate. If the fit is sloppy, if the antenna would wobble when mounted, trade it out for another BNC male connector from your parts stock or purchased separaetly.
NOTE to QRPguys: be aware of this issue and supply better, more substantial (tighter) BNC male connectors in the kits that you sell.
As I mentioned last week in a comment on one of the previous posts about the AX1. I’ve been using the DS1 for a year of so with great success. I highly recommend it. It works well and you can have some pride in yourself for building it on your own.
For a born-again ham who doesn’t even have a radio yet (TR-45L on order), I’m good at collecting antennas. Since I like to build, this one is inviting and will be good for comparison with the AX1 that arrived recently.
Thanks Skip, and Thanks Thomas for publishing so often.
Very very cool Skip! Thanks Thomas for sharing this. I’ve built some of the other QRP guys stuff and agree it’s nice quality. I’m definitely going to look at the DS-1.
Thanks es 72 de Brent VA3YG
This is timely for me. I’m on a business trip and I brought my KX2 and an end-fed plus a throw line. I activated a park on the first day, but not without a struggle to get the antenna deployed. I had a 30-minute window the next day but could not find a local park to deploy the antenna. I had at least one QSO a day this year but broke the streak. This antenna would have made it so much easier. I’ll either buy one or design something similar for future trips and quick activations.
I had been considering the purchase of the DS-1 and associated 40m coil–until someone who shall remain un-named convinced me I absolutely had to take advantage of the AX1 February Special 🙂
I’m now awaiting delivery of my AX1.
Can you build it with a Right-Angled BNC?
Pairing it with a KX2 would make it more usable with the radio, and simplifies deployment. Curious…
de W7UDT (dit dit)
Thanks for the write up! Looks like a great antenna. I recently built the QRPguys QRP wattmeter and dummy load since I didn’t have anything that could measure power that low. It works great! 73
This is super cool, thanks. Can you provide more info on that sweet window mount?
It’s just an MFJ-310 window clip (with BNC connectors on both ends), and I added a small screw to attach the counterpoise wires. 73 Skip K4EAK
Thanks Skip for the ‘tip!’ I’ve built several QRPguys kits…
“The Great Ones” as I call them, Steve Weber & Doug Hendricks to name a few…
I want a Hendricks, and own & treasure an Weber 2 band Mount’n Topper. These simplistic and elegant designs are why I play radio (QRP) today…
I have an MPAS Lite antenna, which I can set up with the radio in about 5-7 minutes, using the 17’ whip. SWR is acceptable on 40 and up without a tuner. The MPAS wasn’t cheap, but once I bought it, I have what I need. It works well with hit and run POTA activations; most of mine are short, around an hour or so.
Would there be any utility in buying either of the AX-1 or QRP guys antennas? I know they would be lighter and more compact, but I’m unlikely to be hiking/walking any great distance.
Jim Brand’s answer is a good one. And just to add one other point, I’ve only used the DS-1 when (1) even a few extra minutes to throw up an EFHW was more than I had and/or (2) I thought it would be fun to play around with a compromised antenna and see what happens. In all other circumstances, if you’ve got something that works well, these small verticals won’t add anything to the process.
Jim is correct. It just depends on your goals. You’re right: the MPAS Lite can be deployed so quickly and performs beautifully. I’d only get an AX1 or DS-1 if you think you might hit parks that wouldn’t allow that MPAS Lite ground spike in the ground. That or you plan to travel with minimal gear–that’s where the AX1 or DS-1 would be hard to beat.
I think it just depends on what your goals are. I can have an entire portable kit in a shoebox or smaller, radio antenna batteries etc. Sometimes that’s important to me. Sometimes it isn’t. Sort of depends on your goals. The only other thing I comment, is there are times being stealthy or doing a little hotel balcony portable or something similar favors a tiny little antenna. Again, it’s not something you do, maybe not so valuable.
I think that is just the ticket for my Penntek TR-35, now I just have to check out one of their tuner designs as well! Thanks for the recommendations! Cheers es 72, Davey – KU9L
I’m getting ready to buy & build their Multi-Z tuner kit in the near future, for use with my TR-35.
The other one I am thinking about is the Emtech ZM-2.
The em2 is an awesome little tuner. It’s a fun kit too. I think you could tune a noodle with it.
Sounds great, would like a report of how you like it. I used an MFJ-901B tuner back in the 1980’s & it worked great with my 90′ long wire. I will order the same tuner kit when I catch up with my other 15 kits I have lined up to build. Davey – KU9L
I’ve been using the AX1 with a capacity hat and am shocked at the results. I just use an alligator clip with a wire that Is 18″ long (9 ” on either side) and it brings the resonance to 1 5:1 on 20 and 40m w.o. a tuner which the ax1 needs otherwise. I’m using the 13′ counterpoise elecraft supplies . Another contender in this field is the Comet Toy Box antenna which I have also found to be excellent with a wider range of bands available. I’ve used 40-10 meters quite happily. Both are quite packable There is also the Gaible antenna which is similar but I have not tried it. The Gaible tripod is 5 stars.