For help, please see DDX manual. To purchase an assembled and fully tested DDX-Commercial board please reach out to us over email.
The 'Direct Digital Transceiver' (DDX) project. DDX is a radio transceiver (rig) which is rugged, simple and reliable.
DDX-1 is a 'silent' radio which can be heard almost all over the world!
Current versions:
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DDX-Commercial-3: 10W digital transceiver (Commercial, Latest Upgraded Version)
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DDX-1 R1.10: 5W digital transceiver (FOSS)
For a truly portable backpack setup you can combine DDX with the FT8 Radio Android app.
Sample QSO (from Pune to Medellin on 10m, 15691km) on DDX-1:
QSO with Paraguay:
Who doesn't want a QSO from Medellin after binge-watching Narcos? ;)
Another sample QSO with WW1WW (Pune to USA):
10W+ transceiver based on Pico 2 MCU platform. Beats IC-705 in terms of efficiency and power consumption!
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Single USB-C cable for handling both Audio + CAT control
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True 5W output on all HF bands. It even outputs ~1-2 W @ 50 MHz! (We now just need a 6m capable receiver section to build a 6m digital transceiver).
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Rock-solid PA which handles open, short, and bad SWR conditions (1:10 SWR tested). We knowingly stress-test it with untuned antennas and still manage DX (not a recommended practice for sure though).
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Rock-steady VFO which does NOT drift even under exposed conditions. Yes - it receives WSPR at 28 MHz just fine.
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Reliable T/R switching based on a DPDT relay
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Switchable BPF support to get rid of BCI and other interferences (tested against OTH radar + 100 kW AM station in close visual proximity)
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No toroids to wind (assuming an external LPF bank is in use) ;-)
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The IRF510 final remains as cool as a cucumber (Class-D operation) - a small heat sink is more than enough.
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Avoids problems associated with the 'audio frequency counting' approach used by earlier designs. DDX-1 has a bit-perfect, deterministic TX output.
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It works beautifully with the 'FT8 Radio' app (https://github.com/kholia/DigitalRadioReceiverSupport/). The 'FT8 Radio' app handles FT8 decoding well in real time (Native MCU decoders offer significantly reduced performance at the moment). The app can decode 35++ stations at a time, and even large screens can fill up very rapidly - such is the receiver's performance (with a BPF)!
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DDX-1 comes with a free, open-source AGPLv3 licensed firmware.
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No calibration is (ever) required. Just pick up DDX-1 and it is ready to go on air.
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Low cost (cost-effective)
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Stress tested by WSJT-Z for multiple days
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DDX-1 routinely receives FT8 traffic from 80 to 100+ countries using a simple 5m long EFHW antenna.
Performance of CD2003-with-BPF is >= 80% of that of RSP1 SDR, at least!
It receives WSPR @ 28 MHz ;)
DDX-1 has already made hundreds of QSOs on air.
DDX-1 was tested with the following power sources.
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SUGON 3005D Adjustable Digital DC Power - RECOMMENDED
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USB battery bank with PD 3.0 and >= 35W output and 15V or 20V PD decoy module (RECOMMENDED, safe, portable, durable)
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RUIDENG DPS5020 power supply module (@13v) powered by MEAN WELL / Mornsun SMPS
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3S "12V" Li-ion 18650 battery pack (can be "volatile")
- Use a Common-Mode-Choke (attached between the rig, and the antenna) for
safety against
return/back RF.
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https://github.com/WB2CBA/ADX (the design that started it all)
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http://www.learningaboutelectronics.com/Articles/Low-pass-filter-calculator.php
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https://github.com/kholia/ConsensusBasedTimeSync (receiver comes from here)
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https://github.com/kholia/Si5351-Module-Clone-TCXO/ (VFO comes from here)
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https://github.com/kholia/HF-PA-v10 (PA comes from here)
Ruggedness philosophy: https://www.youtube.com/watch?v=4r7wHMg5Yjg
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https://www.kk5jy.net/three-wire-gp/ (recommended antenna - superb for DX)
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https://github.com/kholia/HF-Balcony-Antenna-System (another portable antenna setup)
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https://github.com/batica81/microphone-library-for-pico (Vojislav's work makes DDX-1 possible)
Are you interested in such projects, and spam-free technical discussions?
If yes, you might be interested in joining the 'HAMBREWERS' Telegram group.