// CQDX.ru
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
- Also works well on 60m, see John AE5X measurements https://ae5x.blogspot.com/2021/11/spectrum-analysis-qdx-on-60m.html
- 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).
- I-Q output mode if you wish to use a PC SDR program for demodulation rather than the internal SDR
- QFU firmware update for lifetime free firmware udpates, easy installation on any PC without drivers, software or hardware e.g. programmer
- Optional aluminium extruded cut/drilled/laser-etched black anodized enclosure (88.6 x 63 x 25 mm)
QDX also works well on 60m, as documented by John AE5X at https://ae5x.blogspot.com/2021/11/spectrum-analysis-qdx-on-60m.html. Outside the range 3.4-14.5MHz, QDX can be used as a receiver, with some loss of sensitivity.
PC Software
Standard digi modes software like WSJT-X and JS8Call works fine with QDX, because QDX acts as a USB Sound card (for Audio) and a Virtual COM port (for CAT control).
There are three types of USB devices in QDX: USB Audio, USB Virtual COM port, and USB mass storage (like a USB Flash memory stick) for firmware update. Drivers for all of these types of audio device are already present on your PC if you are using Mac, Linux, MS Windows 10 or MS Windows 11. If you are using older versions of Windows, then you need to install a driver for the Virtual COM port (audio and USB Flash drivers are already present even on older Windows), the details are in the QDX manual.
Video
Here’s a YouTube video about QDX: https://youtu.be/j6Vnh8eiEpg
Here’s a build-video series by Ryan W7RLF https://www.youtube.com/
Documentation
The manual includes assembly instructions, operating instructions, design details, performance details
Manual (document version 1.06 published 10-Nov-2021)
Price: 60 USD
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