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QDX Rig Brag Thread #qdx

 

Tell us all about your QDX rig, the build, the antenna, tuner, pc, power supply, cabling, software, etc.? Did you have any challenges getting it to work?? How do you plan to use it?

KC8WBK
 

Thanks for this.? I needed to brag.? I dusted off a spot on a shelf in the shack and set the unopened box from QRP Labs on it.? Whew!? I plan on letting the kit, along with its many unopened kit box cousins, mock me until I get around to assembly.? When I do assemble it, my plan is to establish world peace through the use of QRP digital communications.
 

I received my QDX kit a couple days ago, and it went together very nicely. I've build 6 QCX transceivers, so that experience helped me quite a bit. The QDX is a coil-winder's dream: a binocular, a trifilar, a tapped toroid, and six single toroids. I had a little trouble with the binocular RF power transformer, but I finally got it wound correctly.
The RF output power worked out as expected. I run my unit at 10V, and the output power for the three bands are all a little over 5 watts. I had to adjust the 20 meter filter coils just a bit (spread windings) to increase the output power for that band.
My antennas are a 20/40/80 EFHW, and a separate 30 meter EFHW. I match them with this crazy L-match I built a few weeks ago (pic below). It's wayyyyy overkill for QRP, but I've always wanted a match with a roller inductor and a big-ole bread slicer with a vernier. It has a built-in SWR bridge with LED indicator.
The power supply is a cheapie lab supply from Amazon. I like having adjustable voltage for setting output power, and adjustable current limit to protect the finals.
This is my first foray into digital modes. I downloaded WSJT-X and installed it on a Win 10 PC. I was decoding/uploading WSPR spots within a half hour, and I was thrilled to see it all working. It's fun to finally see me as a receiver on the WSPR sites.
You'll see in a thread I posted earlier today that I thought I had damaged my QDX somehow, as it suddenly stopped outputting RF with WSJT-X. I was panicked for a while, thinking I had damaged it irreparably. Fortunately, Evan AC9TU suggested my PC volume was turned down too low. I cranked it to max, and voila, the RF is back! Disaster averted.
I'm going to do some WSPR receiving/reporting tonight, and start figuring out FT8 tomorrow.
All in all, I am extremely impressed with this little guy. I was an electronic engineer for 40 years, and I've rarely seen such an elegant and efficient design. Hans is truly a wizard.


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Dan? W6AZI
 

My QDX has been running for a few days now, so I think it is in a condition to show off.
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https://postimg.cc/gallery/9Zdbj2Q
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My QDX build went well, except I am not too proud of my work on the multi-tap toroid and the trifilar toroid. The multi-tap has a few loose coils and extra side loops, while the trifilar is laying on its side.? But the device works so I will leave it as is.? I was able to fit the board into the case by filing the board track with a triangular file just enough to allow the board and a piece of electrical tape to fit into the track near the trifilar toroid. I found the build to be challenging due to the small size of the device. I had some issues with transmit until I changed out the usb cable to one with a ferrite built in.
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I run JS8Call and WSJTX on a Raspberry Pi 4. The Pi is run headless through a wifi router and I access the display through a VNC connection from my desktop or phone. The wifi router is connected to cell data and the internet. The Pi is running Raspberry Pi OS, a January 2022 version, with the "Build A Pi" script installation of various ham radio programs.
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The antenna is a poorly installed attic dipole with the ends thrown into the dark corners of the attic, laying on insulation. It needs a tuner for 40 meters, although it was cut to resonate when flown in the open air. The tuner is a homemade L-match type. Due to the need to tune for each band, I stay on 40m.
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My goal is to run the QDX 24/7 in JS8Call mode as an APRS gate and to allow for heartbeat and message transfers. I do switch over to FT8 now and then as it is a fun way to spend some time. While for the most part it is intended to be a fun ham device, I also want to be able to use it for emergency communication in the event of grid failure.
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The power supply is a 3W 12V wall wart.? I hope to use a solar charged battery eventually.
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I check propagation with pskreporter.info. I have been spotted in Australia, Europe, South America and of course North America.
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I have a HFpacker amp in case it is needed in an emergency, which should bring the power level up to about 40W. I prefer to run 5W under normal conditions.
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I am starting to get familiar with JS8Call. I think I have it configured in the way I want it, for the moment at least.? I am still learning messaging and chat. I hope to be running 24 hours a day on 40 meters. I am located in Southwest Michigan, 80 miles ENE of Chicago, and depending on conditions, I seem to be able to transmit about 100 to 1000 miles.? I usually hear further than I can transmit. If you see me on the bands, send me a message and say hello.
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I trimmed my attic dipole and rehung it so it is now resonant on 7.078, no more sketchy homemade antenna tuner.? My rig is now a RPi400 (or headless RPi4), a QDX and a dipole. Pretty simple.??

I am very impressed with the QDX.? When comparing my SNR numbers to others, the QDX seems to get out as well as other rigs using 5 to 10 times the power output.

It would be nice to have an excellent antenna, but for my situation at the moment my QDX is doing very well.? If any other QDX operators see me on 40m, please call me or leave a message if I am not at the station.?
 

I replied to this thread, but for some reason my reply posted as a new thread. Here is the link /g/QRPLabs/message/86788

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73, Dan - W2DLC

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