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
