QMX+ first contact

M0RVB

I made my first QSO on the QMX+ on 30m today. It is a nice little QRP radio, the one I have has all bands from 160m to 6m.

A photo of a QRP Labs QMX+ transceiver showing the frequency 7.074MHz and the time 21:37

Getting it on the air is a bit of a fiddle, not caused by the radio itself. I have a very shorrt random wire antenna tuned by a Z-11Pro II tuner that works very well with the big radios but the QMX+ needs to be treated carefully. Tuning at full power is a bad idea because the tuner is going to hit some very high SWR figures and damage to the finals is a real risk. But there is more to this tale...

First off, I wanted to run it from my old MacBook but no matter what I did it would never see any data from the radio - the QMX+ has CAT and audio along a single USB. CAT was working fine in wsjt-x but no audio of any description. So I loaded wsjt-x on the Mac Mini but it crashed every time I tried to set the radio up. Anyway, I wanted to use the rather neat iFTx app on the phone which does FT8 and FT4 and would mean no need to carry a computer.

iFTx does not have a tune facility nor CAT control, not really an issue given the flexibility it offers but it caused an issue. Not having any way to get the tuner to tune the QMX+ would simply lock out and display an 'S' meaning the SWR is too high. (The S can be seen on the photo above)

Now, given it is a bad idea to try to tune at full power anyway, I read some info on the mailing list that it is safer to use the radio's facility to do an SWR sweep. That has a tune function but in order to access it you need a console connection to the radio. I slept on that...

...and today tried it for real. Hooking the USB to the Mac Mini and using 'cu' (9600 baud) I got into the relevant menu and the tuner found a good match. Plugging the USB into the iPhone via an adapter I then managed a QSO via iFTx. Neat.

A screenshot of iFXT on an iPhone showing a number of FT8 calls and a waterfall at the bottom

The photo above was taken during my initial tests, basically to see why the MacBook saw no audio - proving the QMX+ was working fine. But I got no further as outlined above. And, below, the successful QSO from today, but this time no GPS

A screenshot if iFXT on an iPhone showing a successful QSO.

 

(I should proably edit out the whitespace in that photo!)

For now, this was a test. A real test will come probably one day when I am at the railway. I have a magmount and a 40m whip to use, plus I have a Z-Match QRP manual tuner on order. That does not get round the issue with iFTx not having a tune function which would be neat, but at least with the whip it should have a decent enough SWR to not upset the QMX+. Anyway, I will take the nanoVNA along to set the SWR. Plus this sort of expertimental stuff is all part of the fun!

One thing to note about the QMX+ is it needs 12V, not any higher. So running it off the car or even a charged LiFePo battery means there must be a dropper. I could use a string of diodes, but also I have a little voltage converter set to 12V output.

 

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