I have been experimenting with WSPR for a couple of years now on 40m with my QCX classic and most recently with my new fabulous Mini.
I have experienced a very curious condition when the rig has been off or I have been using it for QSOs. I am finding when returning to WSPR it seems to take a period of time before the rig is "discovered" again by receiving stations.
For instance, last night after powering up, nothing for over 2 hours and then they all piled in.
For WSPR, the rig is running with a GPS permanently attached for discipline, and I have the frequency set bang in the middle of the 40m WSPR band at 7.040100.
It is almost like something is aligning or settling down but I can't put my finger on it. I have a vague notion I have read of something similar some time back on here.
I wondered if anyone else can shed light on it?