Tuesday, January 29, 2019

SSB for QCX?

If you're one of the many billions of hams who own a QCX CW transceiver kit designed by Hans G0UPL, you may be interested to know that, through firmware modifications and 4 minor component changes, a CW-only transceiver (by design) is now operating SSB and FT8.

Guido PE1NNZ is the genius behind the re-writing of the code and he invites others to experiment and tinker with his work-in-progress.

In his own words:

"Over Christmas I have been playing around with a simple modification that transforms the QCX into a Class-E driven SSB transceiver. With this setup I have been able to make several SSB contacts and FT8 exchanges across Europe and so far this experiment is working reasonable well. It can be fully-continuous tuned through bands 160m-10m in the LSB/USB-modes with a 2200Hz bandwidth, provides up to 5W PEP SSB output and has a software-based full Break-In VOX for fast RX/TX switching in voice and digital operations.
The SSB transmit-stage is implemented in a completely digital and software-based manner: at the heart the ATMEGA328 is sampling the input-audio and reconstructing a SSB-signal by controlling the SI5351 PLL phase (through tiny frequency changes over 800kbit/s I2C) and controlling the PA Power (through PWM on the key-shaping circuit). In this way a highly power-efficient class-E driven SSB-signal can be realized; a PWM driven class-E design keeps the SSB transceiver simple, tiny, cool, power-efficient and low-cost (ie. no need for power-inefficient and complex linear amplifier with bulky heat-sink as often is seen in SSB transceivers).

An Open Source Arduino sketch is used as the basis for the firmware, a hardware modification bypasses the QCX CW filter and provides a microphone input in-place of the DVM-circuit; the mod is easy to apply and consist of four wires and four component changes and after applying the transceiver remains compatible with the original QCX (CW) firmware.

This experiment is created to try out what can be done with minimal hardware; a simple ATMEGA processor, a QCX and a bit of signal processing to make SSB in an artificial manner. It would be nice to add more features to the sketch, and see if the QCX design can be further simplified e.g. by implementing parts of the receiver stage in software. Feel free to experiment with this modification and let me know your thoughts or contribute here: https://github.com/threeme3/QCX-SSB"


  1. Very interesting thanks 73 SV1GRN

  2. My friend had one's, i shall declare to him, i hope not so deficult...... de YB3SZM

  3. Interesante voy a buscar más información sobre el equipo como cuanto cuesta saludos cordiales YY-5ATC José González de caracas Venezuela

  4. Very interesting enjoyed.
    Too bad I do not know CW, I have handheld radio I have Yaesu FT897 but I do not know CW and I do not even know how to configure the FT897.
    I would like if someone would know how to configure this radio Yaesu FT897 to use in the manipulator indicate me or even make a video of this and put on Youtube.
    Oliveira pu2OLT
    Blog: qsldobrasil.blog.spot.com.br