QRPp WSPR and FSKCW tests on 40m using the U3

I recently built the QRP-Labs LPF switching board plus a couple of extra filters for 80m and 40m. I’d had these kits gathering dust for probably 12 months plus. Other projects had taken priority and I’d not really run any QRSS tests for a very long time. The New Years 24 hour QRSS event got me looking at the U3 again.

The new board and filters plus firmware upgrade (new chip) all went well and the U3 was soon running again. The U3 with its ~200mW to my very old, not very high, W3DZZ trapped dipole was actually making it across the pond!


U3 running ~200mW to a W3DZZ


Yesterday I decided that it would be good to make it a bit more of a challenge. So many people seem to be be going up in power, so let’s see what dropping down to ~20mW can do. I happened to have a spare BNC in-line 10dB attenuator available, so this meant simply unplugging the antenna and inserting the attenuator. We were then all set to go, with an easy route back to QRO if needed.  🙂

The results over the last 24 hours have been surprising. My beacon hasn’t made it across the pond (yet) but the best so far has been a -28dB report from RK3LC in KO64at. That’s a distance of just over 2108km… not too bad for ~20mW!  🙂


U3 running ~20mW to a W3DZZ



Maybe I will add an extra 3dB attenuator next…    😉

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