Other SOTA sites: SOTAwatch | SOTA Home | Database | Summits | Video | Photos | Shop | Mapping | FAQs | Facebook | Contact SOTA

QCX Mini Part 2

Yes, that’s a good technique!
I wound my toroids in the dark yesterday evening whilst XYL was watching telly. I took a photo of a part wound T1 to count the turns.


T1 looks like it was “machine wound”. Absolutely beautiful job.


A piece of tapered dowel (or paintbrush) in a vice makes life a hell of a lot easier:

       73 Matt

For the 3D printer folks, there is this toroid winder aid

Btw. did anyone perform the SSB (usdx-mod) for the QCX Mini?

Might give it a try to have a monoband lightweight SSB/CW unit for my longer hikes.

73 Joe


I think I will order one for fun.

Yesterday during sota activation I had two “freeze” with my new 20m QCX Mini. need to reset. Have you any feedback about this ?? I activated severall time with my 40m QCX pro and I never noticed this problem.
Best 73,

Did you notice if a “G” popped up on the screen when it froze? I’ve seen that happen before when RF gets into the paddle cable. Since the GPS and paddle use the same IO ports on the processor, if the Mini thinks that a GPS is connected it will lock out the paddle.

This was with an original QCX, but the design is pretty much the same.

I didn’t notice any “G” … but as I have forgotten my glasses in my car 300m down :grin: … the paddle continues to work, Rx too … but no way to modify the screen with buttons

I did the first field test with my QCX Mini 17m yesterday, on ON/ON-013. @G0UPL

Power was from the 3-cell battery box (see an earlier post), antenna a half-wave “Fuchs” antenna (length 8.9m), sloping from abt. 6m above ground to 0.5m (tied to the arm of my chair … ensuring “armchair” copy, hi). A 4m counterpoise completed the setup.

[ @F5MDY No “freeze” noticed, but maybe you used the “turn the speed to ZERO” trick for tuning up with a carrier. After unkeying, the rig does not transmit any more, but RX stays muted. The EXIT button gets you back in RX mode. It does not happen if you set the key to Straight via the menu, or if you use full-QSK (Semi QSK OFF). ]

Strange enough, despite many CQ’s on 18.092, and being spotted on SOTAwatch, I got only one reply from UR5IRM, who gave me a 559.

Time for plan B.
Adding 2.2m of wire to the antenna, and retuning my Fuchs tuner, I started CQ’ing on 14.062, with reduced power of 4W, and reduced RX sensitivity of about 1 S-point.
I almost fell off my chair when the first reply was from no one else than … ZL1TM !
He was a good 539 with me, and he gave me a 509.
That was the first ZL in my SOTA log. WOW.

Further QSO’s with OH5RP, EA5K, EA7GV, OH6JUM, EA7TG, SV2OXS and YL2TQ proved that “abusing” a QCX on the “one lower” band is certainly feasible.

To please the non-CW chasers, I switched to the KX3 to calll a bit more on 40m SSB, and ended the activation with 21 QSO’s in the log.

I will make a longer report of my SOTA excursion later.



Ok, probably not the same issue. With me, I would start keying, the “G” would pop up, and no response from the paddles. It only happened during one outing.

@ON7DG : thank you Luc for your suggestion but unfortunately, it was not the effect you describe and my configuration is IAMBIC-A and Semi-QSK OFF

@N1RBD : I re-read the documentation and effectively there is a protection when I suppose rapid signals are present on the paddle connector i.e. the system thinks that a GPS is connected. It is clearly written that in this case, the system enters in practice mode to protect the PA and this corrupt menu entry. As I tested a new manipulator ( https://www.thingiverse.com/thing:3220538 ) with a poor wired connection (rapidly made before leaving for the activation)… perhaps this setup causes bouncings or EMC. I should be aware the next time… with my glasses.

1 Like

I would definitely try a type 43 ferrite on the feedline, it solved my problems. I use the Fuchs ATU from QRP Shop in Berlin. It seems that, whilst it will work satisfactorily without a counterpoise, there can be some RF on the feedline, at least on 80m. This may be true for other types of end-fed antenna as well. Whilst other radios will tolerate this, the QCX is quite sensitive it seems.
73 de OE6FEG

Thanks a lot for your explanations, Luc. I’ve just finised BPF toroids adjustments on my new QCX mini, ending with 4 w @ 11.7 v.
73, Mikel

1 Like

Well, this just arrived in time for my 40th birthday :smiley:

(/me wonders what goes on the back burner in the interim)


I just finished my 17 meter QCX mini. No smoke, but also no alignment with the 3 potmeters. C1 for the BPF works well. So I have to look closer what’s wrong. First I will measure the OPAMP voltage.

I hope it’s not a faulty OPA…

To be continued. :frowning:

1 Like

Happy birthday, Andrew!
And have fun assemblying that QCX Mini.



1 Like

Try to start positioning all three at the middle point, and from there adjust, there is a lot of people with the same problem. Best regards!

Happy Birthday! I’m quite jealous, MIne shipped on Feb. 16th - still waiting. But it’s a few weeks left till my birthday, hi
73 Martin

Ordered mine yesterday including the components for the uSDR SSB modification.
Lets see how it goes.

@VK3ARR: Andrew have a Happy Birthday and enjoy off-time from babysitting the SOTA IT systems :grin: