3 ms·

For a really good time, I suggest https://github.com/JamesP6000/WsprryPi https://github.com/JamesP6000/WsprryPi - it is super fun run a signal into a long wire

by cadr 9y ago

For a really good time, I suggest https://github.com/JamesP6000/WsprryPi https://github.com/JamesP6000/WsprryPi - it is super fun run a signal into a long wire and see it picked up around the world! (You do need an amateur radio license for this, but in the USA at least the technician one is very easy to get.)

j_s 9y ago
For the semi-serious there is a pre-made filter "temporarily unavailable" (2018-01-15) for purchase: Raspberry Pi QRP TX Shield for WSPR | https://www.tapr.org/kits_20M-wspr-pi.html https://www.tapr.org/kits_20M-wspr-pi.html the harmonics are filtered by a LPF, and the broadband noise is filtered by a BPF [...] a buffer amp is provided for isolation. This also provides a boost to the TX signal And this project ties in an RTL-SDR for receiving: https://github.com/ha7ilm/qtcsdr https://github.com/ha7ilm/qtcsdr mentioning AM/NFM/WFM/LSB/USB [...] although NFM/WFM works as expected, the AM/SSB modes need a much higher level of filtering
- sgtpepper 9y ago
  Building your own LPF is surprisingly easy and educational!
  - cadr 9y ago
    Specifically, I would recommend searching for "W3NQN CWAZ" filter. Look at http://www.kitsandparts.com/ http://www.kitsandparts.com/ for the toroids.