Many thanks to Karl (K5KHK) for sharing this guest post, which originally appeared on his blog, Karl Heinz Kremer’s Ramblings:
A Digital Station in Your Pocket
by Karl Heinz (K5KHK)
How small can a complete station to work FT4/8 be? With the QRP-Labs QMX, we have a transceiver that certainly fits the bill for a small station. By itself it can only be used for CW, to use the digital modes, one has to combine it with a computer. Even the smallest laptop is too big the fit into the pockets of my cargo pants – we are trying a pocket sized station after all 😉
In this article, I will describe how to use a QMX transceiver and an iPhone to activate a POTA park with FT8.
The Components
My QMX is the original that was released at FDIM 2023, so it covers 80m to 20m. Mine is serial number #20.
My iPhone is small enough, but unlike Android based phones, the QMX cannot be connected directly to the phone. Apple sells a “camera adapter”, which plugs into the phones Lightning port on one side and provides a USB connection on the other end. $29 for the original Apple part was a bit hard to swallow, so I opted for something cheaper straight from China’s “we clone everything” factories: https://amzn.to/3WDSfUc
[Please note: All Amazon links are affiliate that support QRPer.com.]
The picture shows both a USB and a lightning port on the adapter. This should allow the phone to be powered/charged while the adapter is being used – more about that later.
Another limitation is the antenna: The QMX does not have a built-in antenna tuner, and even my QRP sized ZM-2 would have to live in a different pocket 🙂 My plan is to use a resonant antenna so that I would not need a tuner.
The easiest antenna with a good match is a dipole, but that is a bit more challenging to deploy in the field, so I opted for an end-fed halfway (or EFHW) antenna with a 49:1 transformer. I 3D printed a winder that allowed a BNC connector and the transformer to be mounted on the wire winder:
The design came from Thingiverse: https://www.thingiverse.com/thing:2871679
Because I am using a different toroid for the transformer, I had to remove the “bump” that is holding the toroid in place. Going forward, I may change the design a bit more to have so that I can fit more wire on the winder.
For those familiar with the transformers usually used for EFHW antennas, the picture shows two things that are different: As I’ve already mentioned, I am using a different toroid (the Fair-Rite 2661102002 core, which is a type 61), and a different winding pattern. More about that in a future post.
To power my station, I am using a TalentCell rechargeable 12V power bank: https://amzn.to/3snTyr8
First Test
With everything in place, I tried to make a quick FT8 contact from home with this setup, but with my “big” EFHW antenna in my backyard. Because it was just a quick test, I did not even bother to hook up the charging cable for my phone (more on that later).
The software I am using is iFTx, which supports both FT4 and FT8.
I connected the phone to the adapter from above, connected the adapter via a USB cable to the QMX, and connected the QMX to a 12V power supply (unlike anywhere else in ham radio, 12V here means 12.0V and not the usual 13.8V), and hooked up the antenna to an antenna tuner and then to the EFHW in my back yard.
I answered an FT8 CQ call and successfully completed the FT8 exchange. The software does the automatic sequencing of the different messages, so it is very straight forward to use. With this first contact, I verified that the iPhone/adapter/QMX setup does work.
The Real Test
The next attempt was while camping at Hamlin Beach State Park (US-2068). I set up everything just like at home, but because I was planning on being on the air for a while. I also hooked up the cable to charge my phone while I was operating.
I was able to receive stations, but could not transmit. What made the troubleshooting more complex is that during setup, I created some sparks (that is why I do not like the barrel connector for power). I was pretty sure that the QMX was not involved, but not being able to transmit kind of suggested that I killed the finals. So I put everything away and used my KX2 instead.
Back home, I did some troubleshooting and hooked up a straight key to the QMX and it worked: I was able to finish a few CW QSOS without a problem, so the finals were definitely OK. I then set up the system again for FT8, and sure enough, I was able to make a contact. Because it was a quick test, I did not bother to use the power cable for the phone. By now, most of you probably know what the culprit was, but because I did not spell things out like this, I was still in the dark.
Success At Last
Fast forward a few more days… We went back to Hamlin Beach State Park – but this time to the picnic area – and I set up my station again. And sure enough, once everything was set up, the QMX did not transmit. This is when I took a step back and reviewed everything I had done so far, and slowly I came to the realization that when I provide power through the adapter to the phone, the QMX would not transmit.
I was able to finish my FT8 activation with my pocket sized digital station. I did run into one problem however: iFTx allows to automatically determine one’s grid square – which of course is important for FT8. When I enabled that, it correctly put me into FT13 at first, but a few QSOs later it switched me to JJ00aa – I reported this as a bug to the developer.
Using iFTx with the iPhone
The connection from the phone to the QMX is audio only. iOS does not allow an application to open a serial port connection (unlike Android). This means that the QMX will not receive any frequency information from the phone, and also no PTT signal. For this setup to work, the operator has to make sure that the QMX is tuned to the correct frequency that the correct band is selected in iFTx, and that the QMX is set to VOX mode (this is in the Digi Interface menu).
When configuring iFTx, it is possible to select a “Special Interest Activity” like POTA. This is then added to the CQ call as in “CQ POTA K5KHK FN13”.
As I’ve mentioned before, the application will automatically sequence the correct messages when a station answers the call.
Once the QSO is completed, it will be logged to the iFTx internal log, which can be exported via the usual “send to” methods available in iOS (e.g. email the log, save as a file, …).
When exporting the log, there is a choice of exporting everything, or only the new QSOs since the last export. This will create an ADIF file, which can be submitted to the POTA program, or imported into any other logging program.
At the end, I was successful in building a “pocket sized” digital station based on the QMX, I just need a fully charged phone and cannot depend on charging it while operating.
Click here to check out more articles from Karl on his blog!
If I’m reading this correctly, the failure to transmit is due to iOS not allowing correct communication through a COM port, but the QMX will react to an audio stream as a substitute. It that a fair reading?
Thanks
P.S. The only apples we have are for eating.
Correct, iOS does not allow a “normal” serial port connection. You can do it when you use BLE (the newer version of Bluetooth), but not through the cable. The USB port does allow to connect audio and MIDI devices, keyboards, cameras (hence the name “camera adapter”), and some storage devices. The QMX does support VOX for the digital modes, and it will trigger the transmit functions when audio is present.
Thanks Karl. Gives me one more reason to avoid Apple products. 🙂
Seriously, very impressive work and I agree that the QMX is a wonderful little radio. Love mine and I’m not even trying digi anything. Thanks for the FB report!
72
I wonder if you could charge the iPhone with the wireless charger while activating? I think I will give this a try. Thanks for the great post! May have a nice lightweight option to take with me when I am flying somewhere. 72 de AD0AA
I have not tried a wireless charger, but that’s a great idea.
Thanks,
Karl Heinz – K5KHK
Nice work, but we are still a ways from a true “pocket” digital mode kit.
In this case, the need for a “resonant” antenna means the winder assembly and coax cable which I doubt fits in the pocket. Secondly, iFTx is pretty awful (at least as of 2 months ago when I tried it), being nowhere close to a WSJT emulation.
My (perhaps flawed) take is that our current best hope is follow through on the Elecraft KH1 being worked out for digital modes, which has been rumored. The KH1 is a true pocket xcvr for CW, the radio/whip/earbuds/counterpoise/BNC to male banana plug and (fill in your favorite length of wire, I use 35 ft.) without need of winder or balun WILL fit in one’s pocket, giving you some antenna flexibility.
As far as the computer part though, unless someone brings a proper FT8 app out (BTW, I am not discounting the idea that iFTx may be the way it is partly because of Apple limitations), I suspect finding a used cheap Android phone for FT8 use may be a better bet, though I don’t know how good the FT8 apps for Android are. Best of all, would be a Windows based tablet to use actual WSJT, but we are now “out of pocket”, so to speak.
But a fine job shrinking things down, at least. The QMX is a little miracle on its own.
73, Kevin K3OX
Kevin, my cargo pants have pretty big pockets, and I can keep the antenna winder, the QMX and the battery in one pocket 🙂 I agree that iFTx does need some work, but it’s a good start. As you can see in one of the pictures, I have a mini straight key that goes with the QMX. With that, my station is even smaller because I don’t need the dedicated 12.0V power source and my phone.
Now, if Elecraft wants to give us other modes in the KH1, I am all for that. With the built-in tuner, that would be the perfect solution (but again at roughly ten times the price of a QMX – I can buy a lot of cargo pants for the difference).
73,
Karl Heinz – K5KHK
That’s my problem, I don’t wear cargo pants! But I do provide enough of my own cargo 😁 so there’s that.
I mean NORMAL pants pockets. I work in NYC and can walk around the area of my job in casual work clothes with the KH1 essentials aforementioned and no one would know.
I will leave the users to decide on iFTx merits, but I still find it lacking versus the Nobel prize winner’s efforts😜
Personally, I would rather have a KH1 than 100 pairs of cargo pants, or 7 QMX’s (though I do have a QMX and a QMX plus).
But it’s always cool to see how folks kit up their field radios of choice, one can pick up ideas for themselves. Thanks!
73, Kevin K3OX
Kevin,
I love my QMX. It’s paired with a 12v 3aH TalentCell battery (velcro’d), a Palm Pico iPaddle, a EFλ/2 PackTenna (20m), and I use the Android Samsung S20 Ultra running FT8CN.
The app seems easy enough, but I still haven’t mastered it. It seems like its working, and the map feature is cool. I wish someone would put out a tutorial…
72 de W7UDT
I’m using USB-C PD to power the QMX from the same power bank that’s keeping the phone charged. Anyone else?
Charlie/WA4APL
That’s how I power my USB-C powered Mini-PC & X6100, using a UGREEN 145W dual USB-PD port powerbank.
I am living in the smart phone stone age, no USB-C for me yet 🙂 Once I upgrade my phone, I might invest into a USB-C power pack.
If you are wondering “What about me?”, an Android user, check out FT8CN, you have to load it thru the browser, it was not in the playstore, when I loaded it. You can Duck-Duck it and find the download. FT-8CN can connect to your radio via bluetooth, usb, or network… With the 705 it will use the radios wifi access point. Ly2H has a great vid with the 705… 73’s all, and thanks for the article Thomas, enjoyed it, even though not an apple user..
Which key is that and where did you order?
Thank you Karl, Very nice kit!
Hi Rhett, the key is from American Morse, and you can find it here: https://www.americanmorse.com/ms2.htm
It is a very cute key but not easy to use. I love my straight keys to have a little more resistance than what’s possible with such a micro key, but on the other hand, it fits perfectly with a small rig. For my bigger POTA setup I use this: https://www.americanmorse.com/kk1.htm – this is a great key.
Thank you, Karl!
Hello,
I just got a HF QRP swr 8 band transceiver. I would love to be able to do FT8 with it. I believe it is the latest model. It is black with 3 buttons on front right side of the front panel. On the right end when you face the radio it has the following. 5 – 3.5 mm jacks.
Top left is key below that is PA. To the right is mic keep going right is a jack marked UART and all the way right is jack marked speaker.
I Wes planning on using an interface that has volume controls for both speaker and mic. With a USB output. Do you think using this setup with the IPhone adapter would work?
Thank you for any help you can give me.
Gene
WO2W.
Without trying it, it’s impossible to say. I don’t have any first hand experience with these radios. There are also straight audio interfaces for iPhones. Depending on how old your phone is you may need a Lighting adapter, or for newer phones a USB-C adapter.
Ham radio is all about experimenting 😉
Let us know how it turns out.
de Karl Heinz – K5KHK