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QRPLabs QDX 5 band transceiver By G6TEQ

The QRPLab transceiver is a 5 band and up to 5w data transceiver. It is available in two versions 80m -20m and 20m – 10m. The lower band version does include 60m.

The company offer various choices for the transceiver from fully built to a kit with or without an enclosure. I decided on the kit version with the enclosure as I wanted a self-contained unit, the enclosure is an aluminum 4 piece which provides a very rugged system for potential portable use.

Once the kit arrived it was unpacked and checked to make sure all the parts were correct. The SMD components are already attached to the high quality multi-layer board. The through hole components toroid and sockets need to be sorted and identified prior to construction starting.


The assembly manual very well written and easy to follow with many helpful hints on how to undertake various tasks and construction procedures. Testing instructions are given for various stages of the build.


The kit gives very detailed instructions on which order components must be assembled. This is backed up with comprehensive diagrams of the installed components at each stage.

The assembly manual very well written and easy to follow with many helpful hints on how to undertake various tasks and construction procedures. Testing instructions are given for various stages of the build.

Toroid winding can be a daunting prospect as there are several filters to be would on various parts of the board, again the kit instructions are comprehensive and if followed allow the construction of these without excess drama. Again careful testing at each stage minimises later failure. The use of a fine tip, temperature controlled soldering iron proved invaluable as the board became more densely populated.

Also it was found extremely useful to have some form of magnification available and a means to hold / mount the PCB during construction. The transceiver will work from either 12v or 9v and a decision has to be made early within the construction to allow for the correct winding of the power transformer. That can be seen near the on board buck power supply and the 4 final output transistors.

Again the use of easily available transistors for the finals allows future repairs if necessary due to some catastrophic event (TX with antenna connected etc.)


Final build prior to testing partially inserted into the supplied case. The initial testing is to ensure that the SDR is functioning correctly and that the board has no short circuits. Monitoring the current drawn at power up again shows board is functioning. Details were given in the manual regarding this process. Connection to the PC allowed the relevant drivers to be found in Windows 10 and 11. Older MS systems require the specific driver to be downloaded from ST technologies but there are detailed guidance on how to do this on the QRPLab site. The drivers also work with most Linux distributions and on Apple Mac but some Linux systems may require some command line inclusions to work correctly. Again detailed in the manual.

When downloading the manual or referring to it on line make sure you use the correct one for your QDX version and also the latest version. The developers are constantly improving and updating the product regarding the construction phase. Indeed since constructing mine the method of the Power transformer winding has been changed and updated.

Connection to WSJT-X is similar to most other transceivers simply find the transceiver in the sound card audio list and for cat control use the Kenwood 440 and the correct Com port for control. Once saved operation is the same as any other transceiver in WSJT-X or JS8Call. Other data modes are supported and are listed in the manual.

Firmware updates are provided by the company and it’s a relatively simple process to undertake these updates again complete instructions are supplied in the various manuals. These updates are supplied at no extra cost.

There is an advanced set of test programs available within the QDX accessed by various emulator command functions. It’s not necessary to use these unless they are of special interest to you for configuration. Does it work – The answer is yes you are never going to compete with the high power stations and expect your signal level reports to be lower than previous higher power reports.


Views of activity on 30 using QDX.

There are some fine tuning require of the Bandpass filters to gain maximum output power this consists of compressing or expanding the windings in the respective band filter. Again easily done and open to experimentation as no one winds these toroids the same.

Would I build another one – yes- I have made the second version for the higher bands so now have coverage from 80m to 10m. Each transceiver separately identifies on the PC so you could use them simultaneously.

They are small enough to combine with a small LiFePO4 battery, raspberry Pi running WSJT-X and in headless mode with a tablet or a small laptop to have a very portable data station, at a relatively low cost.

The QRPLab owner is very active on various group sites and indeed there a constant series of upgrades /alterations being suggested, as well as valued support if you get into problems during you build.

Details of Transceiver at










Please see the propagation chart to check if the bands you want to use are open

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