Hi,

First of all, I would like to say that I'm sorry about the question because probably this was asked before but my groups.io search-fu failed me.

I'm putting together a kit to allow me to operate my QMX on 20m/30m/40m, any of you have any good recommendations for the following:

- Any portable antenna that can operate on the 3 bands without requiring a tuner? Bonus points if does not cost 3 times as much as the radio
- Any budget battery options? I see that our USA friends like to use those Talentcell batteries with 12v output or the bioenno LiFePo4 batteries, which sadly are hard to come by here in Ireland, is it possible to operate it using a USB-C battery bank that can deliver 12v PD? I remember reading something about it being risky as they may switch the power and damage the QMX, but I'm not sure if something changed since I saw that.
- Any small portable CW paddles? Bonus point if they can be somehow attached to the QMX case as we see on some other radios.


I'm not afraid of kits, I'm comfortable soldering, and my only concerns are usually winding toroids (I'm always worried that I'm screwing it somehow). Probably now that I bought a nanovna it can help it test the toroids.

Thanks in advance!

73,
Cassiano - EI5HPB

I'm building a similar kit.? Though I'm going ahead and adding a qrp tuner to mine (atu-10).? I'd prefer to not have to, but I've been out with a nice resonant antenna that's proven itself previously with low SWR and good reactance, and not been able to get a good enough match with it at a particular location for whatever reason.? Ymmv.

I have 2 battery options.? I primarily use the Talentcell which is a great battery, especially since its kit also has a 5v usb which is great since I"m also using a Pi 0 and I can have it and the qmx on the same battery.? Alternatively I also have a Lipo battery bank, a few actually, they're all 20w multi-output and none can run the qmx and Pi at the same time, a higher output one probably would but the talentcell is my go-to.?

As far as the PD issue, the secret is you have to plug in the cable FIRST and let the voltage negotiation happen BEFORE you have it connected to the QMX. If you have the cable plugged into the QMX, and then plug the other end into the battery, yeah it's gonna be nasty with the QMX watching the negotiation happen as it tries different voltages starting with 5v.? The trigger cable itself is a device - once negotiated, the PD trigger cables I have all read a solid and consistent 12v (and 9v and 5v, for the different versions) with only the cable plugged in and no QMX, and plugging in the QMX to that cable afterward isn't going to change that (that's the point of the trigger cable).? Ymmv with a different cable (or other trigger device) and/or different PD bank.? I've tested mine works, but can't promise any other combination will.

For antenna.? In another kit I keep a small portable vertical I built that has a 6' whip (from buddipole, collapses to 13", and sorry for the imperial units), different coils for different bands, which I have worked from 10 all the way to 80m with it.? With that whip and 80m coil, it's high Q and very narrow, but just fine for squatting on a tuned freq in cw and calling cq.??I'm also building a new similar one for the QMX kit, a AX1 ripoff that'll do 20, 30, and 40m, starting with Elecraft's replacement whip and building a single multitapped coil around 1/2" pvc which I've calculated the coils and it'll be plenty short to fit in the kit.? Their ax1's 4' whip is nice because its collapsed length (6") will easily fit in any small qrp kit, I've not come across any other whip that will.? This will no doubt need the tuner I mentioned.? Otherwise, I also keep a 40m efhw (or several) with me which shouldn't need a tuner (though sometimes needs touching up), can't get 30 with it but probably could with a trap.? K6ARK's tiny efhw would be a remarkable addition to the kit and will easily get 20 and 40m.? If you like wires, K6ARK mini efhw is my recommendation.? Otherwise, look at Elecraft's AX1.

Paddles - I 3d printed some mini ones off thingiverse.? I've used them for a long time and have printed several.? The paddle design lends itself to the adjustment screw coming loose which is a problem after, say, 50 or so contacts.? I keep a backup and swap it hot and keep going. Then at the end of the day I take them apart and re-tighten them all.? I'm about to work on a remix of the design that'll keep the nut from loosening, but the priority list has a few things above it.

Hope this helps, good luck, 73
Jason KO4NDP

@Jason KO4NDP: please provide the thingiverse link of the paddle you can recommend.

Thanks & 73

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On Thu, Feb 22, 2024 at 09:33 AM, Martin Hanraads wrote:

3 supports, centre and each end, which means carrying more stuff. However, if you use walking poles, they would do for end supports.

I use long string extensions to the EFHW instead of end supports.? If the mast is near the operator the wire goes up with only a short extension string to elevate the matching unit.? The far end of the EFHW has several metres of string (actually 1.6mm nylon blind cord) which keeps the end of the EFHW at about half the height of the mast.?
73
Rod

I would highly recommend an endfed halfwave antenna kit.

K6ARK makes a nice halfwave transformer kit for about $30 that will handle the power levels of the QMX easily and is not much larger than a BNC connector.? You can also roll your own 49:1 transformer easily as well, but the K6ARK kit is hard to beat for form factor and not expensive.? Just adjust the radiating element for 40/20 or 30 - I have an "extension" on my antenna that is a couple ring terminals and a nylon nut/bolt that I use to add length to my antenna for alternate bands.

For batteries, a small 3s drone battery with a low voltage beeper alarm is light, small, inexpensive, and very dense power storage.? You should be able to get a decent battery, charger, and accessories for well under $50 and possibly even in person anywhere that sells drones or RC gear.

Let me know if you have questions, I can bust out my kit and take some photos!

What part of Ireland are you in?? I went to visit some time ago and spent inordinate amounts of time enjoying the trad music scene in county Kerry - It's beautiful countryside over there!

-N1EDC

If you have a 3D printer you can do a lot of this cheaply.

I would recommend a trap 20/30/40 EFHW antenna.? Links are fine if you don't mind dropping the antenna to change bands, but the trap antenna is easy enough to build and works very well.? There are plenty of designs available on the internet, so you don't need to buy an expensive kit (K6ARK's kit isn't very expensive, but there are companies out there who will charge you $100 for something you can put together yourself for $30).? I've tried several cases for the transformer and it really is user preference here.

You can make your own battery pack with a 3D printed case.? The first one you build will be more expensive than a Talentcell because you'll also need a charger, but they are cheaper if you make several.? I've made a few for my (tr)USDx's, and I plan to make one for my QMX.

Again, there are several 3D printable keys available.? I use a single lever paddle designed by K6ARK.? It isn't connected to the rig, but it works well and is cheap - particularly if you make several.

73,
Mike, KL7MJ

For my portable QDX setup I'm working on (going to try and build a 40/30/20/15 version)... I ordered an EFHW kit from QRP Guys, which has a built in match/single knob tuner and an LED SWR indicator.?
Thinking I'll set up a linked wire setup with it.?

-Nate?
N8BTR

@CoolDuke - The one I've made several of is

and I've also made the same guy's larger base mounted version, it's on a piece of 1/4" stainless steel which turned out to not be large and heavy enough to stay down so it's still a 2 handed operation unless I tape it to the desk.


Check out the existing remixes on them, the base mounted at least has an improvement for the paddle to hold a nut which will prevent it from coming loose as easy.? The mini really needs this too and if I ever get around to it will remix it myself and add that and a couple other improvements I feel it needs.? 2 of the minis have a pen spring, which is ok.? The other (and the base mounted) I glued on opposing neodymium magnets which makes the action feel a lot better imo.? I also like the retractable cable which is a nice portable kit addition.

(sad qmx in the background, will be having surgery performed in a few days)

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