U3s surprise #40m #wspr


Hi WSPR fans,
I built a U3s a few months ago and run it now with about 1 watt on 40 meters. I usually get quite some DX spots in Australia, NZ, Japan, Brazil, Europe, and sometimes Antarctica and Africa. My box has an extra switch for the PA so I can switch off transmission without stopping the whole unit when I reconfigure the antenna, which I did yesterday evening. This morning the map showed only two spots from my station, one in Utah 917 KM, and one to California 650KM. All the DX from the previous days is gone. I found the cause quickly, I forgot to switch the PA power on yesterday. But I was puzzled that I got two spots on the first skip with no PA power. My antenna is an inverted windom. I measured the xmit power with the PA power off on the U3s and found that -7.6 dBm power (170 microwatts) feeds the antenna through the non-functioning PA. This is QRPPPP. Amazing!
Happy WSPRing!
73 de AA0JR Jakob Arizona

Join QRPLabs@groups.io to automatically receive all group messages.