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QMX: What a great radio and fun build!

 

So I just had to make this post because we mostly read here about the problems and issues some people are having with their builds.
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My first real kit build in three or four decades.? I recently retired, and I have some time now, so why not?
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Unlike so many posters to this list who seem to have every imaginable problem - my radio (the QMX mini version mid-band kit) arrived quickly, and was kitted perfectly, with exactly the right components and parts.?
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And following the assembly documents I was able to build it and it worked completely the first time I turned it on.? I did take my time, a few hours a day over three days, and I inspected my work as I went.? And I made a mistake or two, like flexing the tapped wire on one of the coils too much, so it broke off - but I recovered from that without re-winding by soldering on a new piece of wire at the tap point.? And I had to figure a few things out - for example, when I first tried to hear audio, I found I had to turn the volume control a full turn or two up to be able to hear the receiver - the default setting for the audio encoder doesn't behave like a common single-turn low-to-high volume knob.? But otherwise, all is well.? Recieves signals well.? The diagnostic tests all perform and produce waveforms as documented in the operations guide.? And an external power meter agrees with the power values on the diagnostics screen.
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So... Excellent kit.? Excellent instructions.? Excellent radio design. ?
Thank you, Hans, and all who work with you to make this such a positive experience.
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I made a good number of FT8 contacts in my first few hours of using my new QMX with WSJT-X on my laptop, and I did so on each of its bands.?
Now I have motivation to get better at CW so I can use it, too. ? I got a nice mini paddle to practice with.
I also got the QMX working nicely with the FT8CN app on my android phone, so I have a very small package to take hiking with me. ?
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All is well. ?Very enjoyable kit-building experience. Thank you again.
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I may decide to open it up again at some point to see if I can play with the inductor windings to increase the power on the top band (15M), since it is about 3.5W rather than closer to 5, but that is definitely a minor issue, less than half an S-unit - and I'm making lots of good QRP contacts with it as-is.
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Stan KC7XE
 

I too recently built a QMX-Mini Mid Band, I did it over a week in a section a night, checking double checking. It helped that I had built two QMX Minis previously (which I learned a lot from). Good solder joints, removing the enamel from the transformer wires is most of the problems I had in my first kit build from QRP Labs. I agree, Hans is outstanding with these kits.
 

I meant two QCX Minis previously :)
 

Just to be clear: while I have had frustrations, and genuinely despair of getting my first QMX+ build up and fully functional...I am neither giving up on that build, nor on QRPLabs kits. I am a novice and building this kit was a stretch for me, and I knew it!

The kit is excellent, the instructions are excellent, and the feature set the radio offers now, and will offer in the future, are also excellent. I could wish for more "n00b guidance", but I knew the "job" of building one of these was dangerous when I took it on! :-D

Michael WD0OM

On Mon, Sep 30, 2024, at 15:15, Stan Dye wrote:
So I just had to make this post because we mostly read here about the problems and issues some people are having with their builds.
?
My first real kit build in three or four decades.? I recently retired, and I have some time now, so why not?
?
Unlike so many posters to this list who seem to have every imaginable problem - my radio (the QMX mini version mid-band kit) arrived quickly, and was kitted perfectly, with exactly the right components and parts.?
?
And following the assembly documents I was able to build it and it worked completely the first time I turned it on.? I did take my time, a few hours a day over three days, and I inspected my work as I went.? And I made a mistake or two, like flexing the tapped wire on one of the coils too much, so it broke off - but I recovered from that without re-winding by soldering on a new piece of wire at the tap point.? And I had to figure a few things out - for example, when I first tried to hear audio, I found I had to turn the volume control a full turn or two up to be able to hear the receiver - the default setting for the audio encoder doesn't behave like a common single-turn low-to-high volume knob.? But otherwise, all is well.? Recieves signals well.? The diagnostic tests all perform and produce waveforms as documented in the operations guide.? And an external power meter agrees with the power values on the diagnostics screen.
?
So... Excellent kit.? Excellent instructions.? Excellent radio design. ?
Thank you, Hans, and all who work with you to make this such a positive experience.
?
I made a good number of FT8 contacts in my first few hours of using my new QMX with WSJT-X on my laptop, and I did so on each of its bands.?
Now I have motivation to get better at CW so I can use it, too. ? I got a nice mini paddle to practice with.
I also got the QMX working nicely with the FT8CN app on my android phone, so I have a very small package to take hiking with me. ?
?
All is well. ?Very enjoyable kit-building experience. Thank you again.
?
I may decide to open it up again at some point to see if I can play with the inductor windings to increase the power on the top band (15M), since it is about 3.5W rather than closer to 5, but that is definitely a minor issue, less than half an S-unit - and I'm making lots of good QRP contacts with it as-is.
?
Stan KC7XE
 

Also checking in to say that everything about my QMX mini midband went smoothly. I took my time and now I want another one just for the fun of the build. All my 73s go to Hans!
 

Thanks fellas!

As sunrise approaches here at QRP Labs towers and the clear blue sky gets lighter and lighter, you already brightened my morning! Thank you!

73 Hans G0UPL


On Tue, Oct 1, 2024, 02:05 James NJ1V via <jdebriyn=[email protected]> wrote:
Also checking in to say that everything about my QMX mini midband went smoothly. I took my time and now I want another one just for the fun of the build. All my 73s go to Hans!
 

I have to agree, this rig has been fun to both build and operate. I have a QMX high band. There was one delay to replace a defective PCM1804, but after that there was no looking back. I upgraded my license from Technician to General and over the next 90 days I used the QMX to work 79 countries (63 confirmed), 45 states, and nine Canadian provinces using FT4 and FT8. All with just an EFHW antenna in my attic. Simply amazing!
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Regards,
Earle KC0KVR
 

Me too:
Saw the RSGB YouTube presentation & wanted to get back into playing radio and understand this new-fangled SDR stuff so ordered the QMX+ kit and built it with the intention of playing & probing around to understand how it works.
I was so impressed by it that I decided not to risk breaking it, plus the fact that Hans indicated that the microcontroller was effectively locked so more difficult (actually impossible) to reprogram.
Nothing for it - I had to buy a QCX+. More through hole components so more soldering than the QMX+ but a very straightforward build. I now have a SDR that I can hack about with to understand how it works.
That said, the QCX+ is damn good but I've got the QMX+ for best so can afford to mess with it. Currently I'm in the process of connecting another micro to the I & Q signals to just do some processing while leaving the QCX processor to drive the local oscillator (Rx only, I left off the PA transistors for now to save accidents).
I've just visited the Newark ham show and was not in the least interested in the shiny black boxes with prices to scare me - where's the challenge & self-learning when you just plug it in & the DX falls at your feet? (they do that don't they - or should do for those prices)
I just hope that Hans can retain the fantastic balance of quality, price & 'ham' ethos that he's achieved and take QRPLabs as a business to where he wants it to be.
I'm a recent? QRPLabs convert, fair to say that my Christmas presents are probably coming from Turkey this year.
 

I¡¯m right there with you all. My journey from Technician to General was through a QDX-M for 10 M on an EFHW. My recently built QMX+ helped me take it all up a level. Thanks to an excellent product and documentation and this community my build was straightforward and minor troubleshooting was easy. I had already learned what to triple check.?
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More details here for anyone with a couple of minutes for more positive energy about QRP-Labs!
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Joe KA1ZNA

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