WSPR on my Raspberry Pi


Here are a couple of photo's showing my Raspberry Pi with a small veroboard containing a lowpass filter. 


The Lowpass filter can be bought in kit form for about £3 from   I also installed a 0.001uf ceramic capacitor (102) between the Raspberry Pi's GPI/O 4 (Pin 7) and the input of the LPF.  You will see I used some some sockets on the veroboard so that I can use other plug-in LPF's for different bands.  The filters are about £3 each so it's not worth trying to make one.  I'm getting about 0.8v peak to peak output measured on my scope and plan to build a small PA to get the power up to about 50mW using a BS170 transistor.