The curse of no luck is broken now I think. (You may ask Armin why.)
73 Ludwig
He told me 
You’re interpretation of expected results is too literal. Depending upon how you build your particular transceiver, you may have more or less power. The difference between 4w and 5w is trivial.
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My QRP Labs projects QCX 30, QCX Mini20, QMX20-10,QMX80-20 for desktop and handled operation.And depending on the situation, the choice is yours.
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I got the 60 - 15m version. Mainly because it has the WARC bands, except 12m and those are handy when most weekends when I go SOTA or POTA there are often contests clogging up the non WARC bands. Also I have a (tr)uSDX made for the classic bands, so if I bring that one as backup I also have 80m and 10m on that one. The QMX sounds really nice , but I have two issues with it, high current consumption on RX, 200mA, and somtimes just noises for audio, usually OK after a reboot or two… So I guess it’s an iffy ADC chip that I need to replace.
Also a bit low output power on all bands, just around 2W. But got many nice QSO’s on it anyways, but need to do a bit debugging work to get it perfect.
You probably remember, as I do, that there was a noticeable jump in output power between versions of the QCX, simply due to better quality components being used. The graph is a guideline, not a hard and fast prediction.
73 de OE6FEG
Matt
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This is my modification to the QMX for hand held operation.
The battery / amplifier compartment is made from a U section that replaces the QMX endplate. A top and bottom lid are screwed into the U section.
Inside the compartment, there are 3 x 3.6V LiFePO4 cells that power the 9V QMX. The QMX audio is amplified by an LM386 minimum parts count implementation.
On the side of the compartment there is a swing out pressure paddle of the VK3IL design. It seems to work fine with loud audio but it hasn’t been fielded yet. I’m hoping it will get me using some CW!
And the QMX is a high band version.
Cheers,
Glenn VK3YY.
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Yes, it’s worth investing in good quality toroidal cores and capacitors.
I’m very impressed by my QMX, I was wary due to the number of tales of disaster but I’m glad I bought the kit. I was thinking that the SSB firmware would be out by around last Christmas, so I put my order in before the anticipated rush, but I was wrong! I do really want the SSB capability. In hindsight I bought the wrong band combination, my interest in 10m has fallen off and 40m SSB would be useful for HEMA. I know I could modify my QMX but it’s working so well, it seems a shame to disturb it.
73, Colin
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Hi Chris,
I have now settled on a final version. QCX 20 & 30m, bushtenna copy @DL1CR as EFHW with a trap so as to have resonance on 20m and 30m (any small whip does not seem to contribute much), integrated Fuchs tuner with bridge and SWR indicator, integrated VK3IL pressure paddle, integrated LIPO 3S 450mAh, HF indicator LED. Homemade enclosure so as to save weight. I did not include a speaker because I don’t use it when hiking. Total weight 326g. A few pictures below.
73, Peter
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Hello Peter,
that looks great, robust, and has everything you need.
I’m glad you want to use the BushAnt.
The day before yesterday, I compared the BushAnt with the 5m telescopic antenna from China. The setup was significantly more complex, and I don’t expect the telescopic rod to last long in the rough and tumble of everyday use.
And the best part: The BushAnt had the most contacts. Okay, I’m biased.
I use a resonance circuit with a trap in the coil. The antenna wire is on a small plastic plate and unwound to half the wavelength. The tuner also tunes the next higher and lower band.
I wish you much success. My QMX version will be ready soon, 73 Chris
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Hi Chris,
I’m biased as well - based on quite a few tests in different locations and different heights. Often surprised how well this antenna does, nicely demonstrated on your recent video. And in terms of speed and ease of deployment hard to beat, it’s basically just like laying out a single radial… And with the little Fuchs circuit, changes in SWR due to different deployment etc. can be ironed out in seconds.
Looking forward to seeing your QMX finished!
73, Peter
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Finally got a power bank working with my QMX 60-15 Edition. Nice to have a small kit to take out in the field. Anyone got any recommendations on setup configurations for CW for it?
The menus are a bit confusing for me as a beginner CW operator so any advice is welcome. Hoping to take it out tomorrow for my first ever CW QSO.
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The QMX SSB went out on an activation today. The summit was Mt. Porepuncka in North Eastern Victoria. Using a loaded end fed half wave on 20m, I worked ZL1HIM who was also using a QMX!
Good clear audio both ways.
Regarding the banding, I’m planning to modify the high band QMX to include 40 metres as per AI6XG’s article.
Glenn VK3YY.
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Having used my (pre-built) QMX a lot over the last few months, I’ve now taken the plunge and ordered the QMX+ kit, to use in my shack. Great little radio, and the responsiveness of Hans and his frequent firmware updates make sure I believe I will keep getting more out of it.
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Hello everyone,
I just purchased my QMX as well, and while I’m waiting for my kit, I started wondering how I can make it as small and lightweight as possible. One of the main questions I had was about the battery setup.
If I build it for 12V, I would use 3×18650 cells, charging them up to 12V and that’s it. But if I go for a 9V version, I’d probably use 2×18650 cells, which would give me around 8V. I also read that the QMX can operate down to about 5.xx volts.
My question is: how does the 9V version behave if I supply it with less than 9V — for example, in the 6–8V range?
In the meantime, I did some research. Please correct me if I’m wrong.
For me personally, going with a DC-DC buck, boost, or using diodes in series doesn’t make any sense.
Thanks a lot for your help!
Julian
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I don’t quite understand your question. The two versions differ only in the number of secondary (i.e., antenna-side) windings in the power amplifier transformers.
Thanks to the effective voltage regulators, reception will remain unchanged down to 6V.
The diagram shows what power is achieved at what voltage.
I personally have the 3:3 version so I can get by with two cells and minimize weight and size.
73 Chris
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Hello Chris,
thanks for answering my question. In the end, what I really wanted to know is whether it’s possible to run with 2 cells and still have enough power. I’ve read a lot about DC-DC converters and people using diodes in series to drop the voltage. But maybe the smartest way is the 3:3 setup with 2 cells, which would also reduce the weight and pack size.
Thanks a lot,
Julian
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I agree. DC-DC converters generate interference, and diodes in series are energy wasters.
73 Chris
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By the way. The QMX also uses internal energy-saving DC-DC converters. However, the frequency is controlled by the mikrocontroller so that no harmonics fall into the respective reception range. External converters can’t do that.
73 Chris
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Hi Julian,
If you’re looking for minimum weight, you might want to consider LiPos. I’m using 3s LiPos and total battery weight, depending on capacity, is 40 to 65g.
73 Peter
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