Posted on 12 Comments

WSPR on 20, 30 and 40 Meters

TAPR now offers its popular Raspberry Pi QRP TX Shield for WSPR in three versions: 20, 30 and 40 meters!

Nowadays, one of the most impressive QRP modes is Joe Taylor, K1JT’s WSPR (pronounced “whisper”) mode. WSPR stands for “Weak Signal Propagation Reporter.” Programs written for WSPR mode are designed for sending and receiving low-power transmissions to test propagation paths on the MF, HF and recently, UHF bands. Users with Internet access can watch results in real time at

TAPR’s QRPi board (or “shield” as referred by the community today) is an inexpensive way of turning a Raspberry Pi single-board computer into a QRP transmitter. The QRPi comes to you assembled and tested.

For more information and to place an order visit the TAPR Shop.

12 thoughts on “WSPR on 20, 30 and 40 Meters

  1. Are we able to work FT8 or SSTV modes with this shield ?

    1. No

  2. It would be nice to have modules for 6/10/12/80 meterbands as well

  3. Information links are broken from the 30 and 40 meter versions. Is this still a viable product? Links still exist for the original 20 meter version. I am interested but not if support is gone… 🙁

    1. All three versions are still viable products and are being supported.

    2. As we transition to our new website, you can temporarily use

  4. I have received the WSPR shields I ordered, thanks!
    Tried to download the PDF documentation for the 40m version, but as said above the PDF link is broken (
    Where can I find the document?
    73s de SM2YHP

    1. As we transition to our new website, you can temporarily use

      1. Thanks! I have downloaded the documentation.
        – SM2YHP

  5. Let me start with I believe you. The links are working for me except the WSPR executables and the SD Card Image. Those are definitely broken. I think I need to try accessing them from another computer – I don’t want to throw away all of my browser history.

    Thanks for pointing out the broken links.

    73 Bruce Raymond/ND8I

  6. Received my QRPi 20M and my 30M WWoT modules. The 30M module is on the air and working.

    The 20M module was installed in RPi 3 B+ with Raspbian Buster, make file crashes on “makedev” plus a lot of incompatibilities, looks as though the source is broken on newer compilers. Changed OS to Ubuntu and same issue.

    Any helpful suggestions?

    1. 1. All of the WSPR transmitters are fundamentally the same. They use the same software (WsprryPi) on the Pi to generate a WSPR signal. They use a MOSFET (MMBF170) to amplify the signal, followed by a low pass filter. The only real difference between any of them is the low pass filter (LPF).

      2. The Pi 3B+ uses a different SoC chip than on previous Pi versions. I don’t really know what I’m talking about here. All I know is that there are hardware differences between the 3B+ and everything that came before it, meaning that the driver level software for earlier versions doesn’t work with the 3B+.

      The author of WsprryPi updated the software to work with the 3B+ and I made a new build with that revised software. It works with everything up through the 3B+.

      Zoltan did the 20m board. I did the 30m and 40m boards. I don’t believe that Zoltan has done a software update to accommodate the 3B+, so I suspect that the software for the 20m board on the TAPR website won’t work with a Pi 3B+. It doesn’t really matter because you can use my build (30m or 40m software) for 20m (as well as 30m and 40m transmitters).

      3. I haven’t been able to get the software to work properly with a Pi 4, yet. Still a work in progress.

      4. The wspr output frequency is controlled by the program, so if it’s at the edge or outside of the band the first thing I’d suspect is the crystal frequency on the Pi possibly being away from the nominal value. There is a parameter you can set to force a frequency offset, ostensibly to counter a crystal frequency error. The program invocation is in the file runwspr in the home directory. I login using SSH (program KiTTY; username: pi, password: wspr. Add the parameter -ppm xxx to the first line, where xxx is your offset. I have not tried this, so I can’t say for sure that it works.

      5. As a side note, I’m working on having the WWoT board made without populating the low pass filter and sending a bag of parts (3 inductors, 4 capacitors) to be installed by the user. This will allow it to work on any band from 630m through 10m. I’m still prototyping.

      6. A 2.25 amp power supply is probably adequate. If you have some strange errors, such as the file system getting corrupted or reboots, … the first thing to suspect is the power supply not being able to supply enough current. The first time something strange happens you can fix it and go on. The second time, replace the power supply with something larger.

      Please feel free to email me with any questions.

      73 Bruce Raymond/ND8I

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