Not a single spot!
10m conditions clearly not up to much today! Powered from a 12v 7Ah SLAB, via a modified 3v/5v regulator board (el cheapo, intended for Arduino and R-Pi prototypes), the U3S was working away quite happily, so I changed the frequency, swapped the LPF, retuned the DX-70, which was acting as monitor receiver, and moved to 40m...
And was spotted a dozen times on the first transmission!
Ive been running on 40m since then, at 10min intervals, heres the spots for the last 6h -
Not bad for a mere 200mW! Rather than try and explain what the U3S does when its running, ive done a little bit of a video of it. This shows it from just before transmission, when during the gap it displays the GPS data, to just after the start of a WSPR transmission
Immediately after transmission, the beacon calibrates itself using the GPS 1PPS signal, before putting the synthesiser into 'Park', that is, running but on a frequency safely away from the operating band, to keep it warm and so avoid drift,
I will try 10m again tomorrow.