Tag Archives: QRP Labs QDX

Activating Silver Sands State Park by pairing the QRP Labs QDX and the FT8CN Android App!

FT8CN Field Report

By: Conrad Trautmann (N2YCH)

February 24, 2024

I successfully activated Silver Sands State Park, K-1716, for Parks on the Air using the FT8CN Android app and a QRP Labs QDX transceiver.  Here’s my field report.

Thinking about ways to further shrink down my mobile kit, I wondered if WSJT-X would run on a mobile phone. After some internet searching and reading various groups.io messages, I discovered that FT8CN is a digital modes app that runs on an Android device. It is also single wire compatible with the QRP Labs QDX transceiver carrying both the CAT control and audio. My goal was to see just how light and compact I could make my digital mode kit. Here’s a look…

Lenovo Android Tablet, QRP Labs QDX transceiver and a Bioenno BLF-1203AB 12V Battery

The Android device is a Lenovo Tab M8 (4th Gen), which can be found on Amazon [affiliate link]for about $80. It has an 8” screen, which is slightly larger than my mobile phone. I was happy to have the extra screen real estate since there’s a lot going on in the app and the size made it easy to see it all.

The FT8CN software can be found at N0BOY’s github site, https://github.com/N0BOY/FT8CN/releases. The most recent revision as of this writing is version 0.92. It’s an .apk file, which to install, you need to give your Android device permission to download via the browser. This is a direct download to the device and not going through the Google Play store, so it hasn’t gone through any security checks or validations. As with any of the software we use in ham radio, caveat emptor, or buyer beware. I would carefully consider this before downloading it to your primary mobile phone.

With that said, if you Google FT8CN, you’ll find plenty of videos and online resources to guide you on how to install it and set it up, so I won’t go into those details here. It’s fairly intuitive and each configurable field has an information button you can click for in-app instructions or explanations of what each does.

The Lenovo tablet has a single USB C port used for charging and connecting external devices, so I used a USB C to USB Type A adapter to connect to the QDX cable. Since this setup only requires a single wire, I plan to use a USB C to USB Type B cable so no adapter will be needed. For the first outing, it worked just fine this way.

The QDX’s on-board audio card and the transceiver control are all integrated into the application. It supports a number of popular transceivers including the QDX. When I connected the USB cable to the tablet, it automatically launched the application and presented a screen to click with the USB port. Once selected, the app displays a message saying the connection was successful.

I brought my Bioenno BLF-1203AB 12 volt battery to power the radio, which is actually larger than the QDX. That’s another opportunity for me to downsize the kit, finding a smaller LiFePo battery. I know some QDX owners use a standard  9 volt battery, that would certainly lighten the load. My QDX is built for 12 volts but it is possible to build it configured for 9 volts and still get full power out.

As pictured above, the entire setup was the 8” tablet, a USB cable connection to the QDX, a power cable from the battery to the QDX and an antenna cable. For the test, I used my Buddipole with a 17’ whip and counterpoise, which I knew would be resonant on 20 meters. I wanted to avoid needing to use a tuner. There is a compact tuner available which is about the same size as the QDX called the ATU-10, which works well if you need one and is about the same size as the QDX. I think it would be great to pair this kit with a Packtenna EFHW 20 meter wire antenna, which is also resonant and tiny enough to pack in a small bag with the rest of the kit.

Equipment List

Extra Items I brought for the test

I did a quick test of my antenna using the RigExpert antenna analyzer and at 14.074 MHz, I had 1.5:1 SWR, so I didn’t need to worry about damaging the final power amplifier on the QDX.

A windy day bending my vertical to one side at K-1716, Silver Sands State Park, Connecticut
AntScope shows a decent match at FT8 frequency.

Once everything was connected, I immediately started receiving stations. Here’s a screen shot of the decodes screen (below). The waterfall is on the left and decode list is on the right.  Odd and even cycles are easy to see with light and dark shading behind them. They are also labeled “0” and “1”.

I think one of the coolest features of this application is the labeling of the stations in the waterfall.

Here’s the same screenshot rotated to see the waterfall more easily.

You can see that the text of the stations calling CQ are a different color than the others. You can also see KS4YT calling CQ POTA. I always try to call other POTA activators when I see them to get the park to park QSO. When a station is calling you, the text is pink. Continue reading Activating Silver Sands State Park by pairing the QRP Labs QDX and the FT8CN Android App!

W7UDT: “Velcro, ergo; ergonomics…”

Many thanks to Rand (W7UDT) who shares the following guest post:

Velcro, ergo; ergonomics…

by Rand (W7UDT)

Velcro is amazing. It’s so handy. There are so many uses, and creative solutions it provides us. It’ll stick this to that, and that to this. As field operators, it should be part of our kits.

Below are some examples of how I’ve used Velcro.

Question: How do you keep a Android tablet, a 3aH 12v DC pack, a QRP Labs QDX LoBander, all its cords & patches, plus an EmTech ZM2 tuner all nice and tidy? Velcro!

Here’s the old QDX kit…

Here’s the new (velcro’d) QDX kit, complete with EmTech ZM2 tuner, neatly attached on the back of the Tablet, with the QDX and DC Pack. It all fits in a zippered pouch, along with the EFλ/2 antenna, perfect for the QDX.

The new QDX kit even sits at a nice viewing angle, with all of the cords hidden from view. Ergo, ergonomics.

Question: Where & how do you safely place your transceiver on a rugged SOTA/POTA activation, so it won’t get damaged?

How? Velcro! What makes more sense? A precarious rock, or the Molle patch on your pack?

This is my QCX Mini ~ Forty, Velcro’d with two horizontally applied 1” strips, with short cords channeled between them. It secures the perfectly mated 3aH 12v TalentCell battery, to which I applied another velcro strip to hold fast the Palm Pico paddle. Also note the ‘D-shaped’ earpiece/speaker, on the BNC jack. It’s hung and velcro’d just above the paddle.

Since this photo, I’ve added three 2×4” (cut to fit) patches to the front, back and bottom of the QCX Mini & TalentCell, which neatly bundles this little QRP contraption and transforms it into a QRP wonder! Now it all fits in my hand, or attaches firmly to my pack. Dit dit dit daw! Velcro!

A view from Zion NP, in the backcountry… late last Spring. Where my little transceiver tried to commit suicide.

Just sayin’… Velcro may be just the answer you’re looking for.

72 de W7UDT ID (dit dit)

Field Radio Kit Gallery: W7UDT’s QRP Labs QDX Digital Mode Field Kit

Many thanks to Rand (W7UDT) who shares the following article about his portable field radio kit which will be featured on our Field Kit Gallery page. If you would like to share your field kit with the QRPer community, check out this post.

Rand writes:

My Digital HF Field Kit…

by Rand (W7UDT)

Thomas & the gang… this is (de) Rand W7UDT

The QRP Labs QDX is yet another, brilliant creation from genius Hans Summers. Hans has created a cult following, with an assortment of kits, and assembled bargains of fun!

Many of you know this, and have his gear. And as sexy and alluring my Elecraft KX2 may be, it’s often, as a minimalist, that I reach for my QCX Mini(s), or my QDX (Hi & LoBanders).

I guess it’s a touch of OCD that compels me to minimize and simplify my field kits. (Yes, I need help!) And yet, if you too, upon reading this confession, find it all too interesting and read on.

Here’s the QDX field deployment in a nutshell…

Deploy the antenna, a LNR Precision Trail Friendly End Fed Wire. With a toss and some luck, the weight clears the chosen branch and the antenna is hoisted aloft.

Often I operate along the Boise River Greenbelt, just off the path near the river. I find that perfect spot to operate.

The flow of water, doesn’t make too much noise, and doesn’t matter with this mode, FT8. Only that it has a sunny view, and it’s comfortable and dry.

The QDX transciever & DC Pack is velcro’d to a clipboard, and once secured, I attach a 6′ section of RG316 and an inline 1:1 balun. The BNC coax is then connected. A trusted prussick knot, attachs the coax and clipboard, and provides the strain relief and work surface needed to operate.

8″ USB c/b cable connects the QDX with my Samsung Galaxy S20 Ultra, to the QDX. The transiever is powered by a 3aH 12v DC Pack of (3) 18650 LiFePo4 batteries. With the swich thrown, it archs to life. I then open the FT8CN app on my Samsung, select the Comm Port, and Wow! What fun!

The software does all the work, and even logs the contacts automatically. An occasional touch to the screen, can have you operating at will. It’s a free app on GitHub, that will pleasantly surprise and surpass any low estimations of ‘Free Chinese Stuff.’

All this can be viewed on YouTube, watch Linas LY2H.

Here’s my assembled field kit for my QDX (LoBander). I absolutely love this thing!

It’s a very tight kit. As simple as Hans ‘the Man!’ can make it. What a capable marvel of creative genius. Here’s a pic…

These modes offer error correction, and incredible Dx. The software function flawlessly, and automatically logs the contacts. Hang it high, and the antenna is happy! Easy, cheap and fun! 72 de W7UDT Rand

Notes ~ FT8, JS8 Call & RTTY Only, using the amazing & free FT8CN software.

Guest Post: A QRP Labs QDX POTA Field Portable Report

(Photo: QRP Labs)

Many thanks to Conrad (N2YCH) who shares the following field report:

QRP-Labs QDX Field Report

K-1716, Silver Sands State Park, Milford, Connecticut

January 13, 2023

By: Conrad Trautmann, N2YCH

A digital mode multiband transceiver for $69? Yes! QRP Labs has the QDX kit available for $69 US. Add $20 if you would like a very nice black anodized aluminum case to mount it in and if you want it assembled and tested add another $45. Visit the QRP Labs web site for all of the details (QDX 4-band 5W Digi transceiver (qrp-labs.com)

How well can a $69 digital transceiver work? Read on…

I ordered my QDX kit back in May 2022. It arrived in June, I assembled it and ran some tests at home. It worked well on FT8 into my home antennas. It interfaces nicely with WSJT-X and I liked the idea of using a low power transceiver to band hop on WSPR. My QDX is an early four band version, which does 20, 30, 40 & 80 meters. I set it to band hop on all four bands not remembering that my multiband offset center fed dipole is not resonant on 30 meters. Since the QDX does not have a tuner, it didn’t like the higher reflected power of a two minute long WSPR transmission into a bad load and smoke resulted. I was fortunate that the failure was isolated to the RF power amplifier transistors and replacing those got me running again. This was my own fault, not the transceiver. Now, it band hops on 20, 40 and 80 meters with no issues, I eliminated 30 meters from the hop schedule.

I share this important story at the beginning of my field report as a warning to anyone considering using a QDX to be very careful when connecting an antenna to it. Since the QDX does not have an internal antenna tuner, you either need a resonant antenna or must use an external tuner to provide a 50 ohm load with low SWR to the QDX. The QRP Labs groups.io site has a number of posts from users with different tuner suggestions.

Now comes the fun part. I visited Silver Sands State Park, K-1716, located on Long Island sound in Milford, CT on January 13, 2023 in the afternoon. While it was Friday the 13th, I had nothing but good luck. Knowing I would be running QRP power, I decided to use what I consider to be my best 20 meter antenna. It’s a modified version of a Buddipole, which I call my “no coil” Buddipole dipole. I use a Buddipole VersaTee mounted to a WILL-BURT Hurry Up mast, which is a push up mast that extends to about 25’ high. The dipole consists of two Buddipole 32” accessory arms, one for each side of the VersaTee and two MFJ 17’ telescoping whips, extended to just about 17.5’. This provides a very broad bandwidth and low SWR on 20 meters. See the screen shot of my antenna sweep from the RigExpert analyzer below.

Here’s a photo of the antenna in the air.

The temperature on this January day was a mild 55 degrees so I was able to set up my equipment in the back of my Jeep. Here’s everything I needed to do the activation. Since the antenna is resonant, I did not use a tuner.

My iPhone gives you an idea of just how big the QDX is, which is sitting just to the right of it. There are only three connections needed, the antenna cable, a 12V power cable and the USB cable. I was using my Bioenno 9ah battery for power. I brought the Bird Model 43 with a 25 watt element in it to monitor the output power and also to measure the reflected power, which barely even nudged the meter. It was effectively zero watts reflected. In the photo above, I was in a transmit cycle and you can see the power meter just a touch above 5 watts. On the computer, you can see a mini pile-up of six hunters in the queue. One thing to note about the QDX is that you can’t adjust the power by lowering the PWR slider in WSJT-X. It’s recommended to leave that at maximum. The way to adjust output power is to adjust the power supply voltage. In this case, the Bioenno had a full charge, so the radio was running full power.

I began the activation without spotting myself, just to see who’d hear me. Here’s a map of the pskreporter showing my spots.

I eventually spotted myself so hunters would know what park I was at. I was amazed that during my activation, I never ran dry or had to call CQ POTA, there was a steady stream of hunters the entire time. The QDX does a fine job receiving, here’s a screenshot of WSJT-X including the waterfall to show what it was receiving.

So, how did the $69 radio do? In a one hour and 17 minute activation, I completed 46 FT8 QSO’s. Here’s my coverage map.

I managed to complete three park to park QSO’s, too. One park called me and I called the other two who heard me and answered. I use JTAlert which helps me keep track of the order of who called. I always try to answer the hunters in the order they called me. I’ve set up a Directed CQ alert in JTAlert for anyone calling “CQ POTA” which helps me to see who else is at a park while I’m activating. If I’m able to contact them, I use the POTA spot list to include their park number in the SIG_INFO field of my log, which is N3FJP. N3FJP is handy to use since I start a new log for each activation and I’ve configured it to upload to LOTW and QRZ when I’m done for the day.

Another thing worth noting is that there is no speaker on the QDX. I’m one of those digital operators who actually listens to the cycles while I’m on the air. It provides a certain cadence to hear each cycle go by so you know what to be looking at or clicking on and when. With no sound coming out of the QDX, it forces you to find that cadence by looking at the computer screen. For me, it means watching the receive audio levels and the progress bar to see if I’m transmitting or receiving. The QDX does have a single red LED on the front panel that will flash during transmit cycles, which is also a helpful indicator.

I’d say the results shown here speak for themselves. I had a steady stream of hunters, I had just one or two QSO’s that needed a second RR73 to confirm and the coverage was as good as most activations I’ve done with more expensive radios and more power. Despite the self-inflicted hiccup I experienced at the beginning, I’d say that If you’re looking to try activating digital for Parks On The Air or even for your home, the QDX certainly works very well and provides a lot of value for the money.

The new QRP Labs QDX 4-band 5 watt digital transceiver kit

Many thanks to Pete  (WB9FLW) who shares the following information about the new QDX transceiver from QRP Labs:

The “QDX” (QRP Labs Digital Xcvr): a feature-packed, high performance, four-band (80, 40, 30, 20m) 5W Digi-modes transceiver kit, including embedded SDR receiver, 24-bit 48 ksps USB sound card, CAT control, synthesized VFO with TCXO reference. QDX transmits a SINGLE SIGNAL, it is not an SSB modulator with associated unwanted sideband and residual carrier, or intermodulation due to amplifier non-linearity. QDX outputs a pure single signal.

The Optional enclosure is black anodized extruded aluminium, very sturdy and elegant. The enclosure size is 89 x 63 x 25mm without protrusions. The front and rear panels are drilled and cut to match the QDX PCB with laser-etched lettering. The enclosure includes four self-adhesive feet.

List of features: 

    • Four bands 80, 40, 30 and 20m
    • 5W output at 9V supply (can be built for 4-5W at 12-13V supply)
    • Single signal transmission (zero unwanted sideband, zero residual carrier, zero intermodulation distortion)
    • Solid-state band switching and transmit/receive switching under CAT control
    • High performance embedded SDR SSB receiver with 60-70dB of unwanted sideband cancellation
    • Built-in 24-bit 48ksps USB sound card
    • Built-in USB Virtual COM Serial port for CAT control
    • Si5351A Synthesized VFO with 25MHz TCXO as standard
    • Easy to build single-board design, Professional quality double-sided, through-hole plated, silk-screen printed PCBs
    • All SMD components factory assembled
    • Connectors: 2.1mm power barrel connector, USB B (for audio and CAT control), BNC RF input/output
    • Built-in test signal generator and testing tools
    • Receive current 100mA, Transmit current 1.0-1.1A for 5W output with 9V supply (around 0.7A for 5W with 13V supply).
    • Optional aluminium extruded cut/drilled/laser-etched black anodized enclosure

Full details, see main QRP Labs QDX page.

Video tour of the QDX

Click here to view on YouTube.

Absolutely amazing! I’m not sure how Hans is able to innovate at the pace he does, but I think we’re all better for it. This will be a big seller for those who’ve been looking for a high performance QRP digital mode transceiver.

Thanks for the tip, Pete!

Click here to check out the QDX at QRP Labs.