This past fall and winter, betterthan-projected solar flux resulted in the 10-meter band being open for DX in all the major contests as we enter the peak of Solar Cycle 25. The peak of the solar cycle also brings with it an increased likelihood for solar flares which can cause radio blackouts. Let’s look at how an X1.6 class flare impacted the August 5 CW North American QSO Party.
Almost a third of the 891 hams who submitted logs for the NAQP CW were calling CQ around 2200Z, right before the flare began. In that hour, as is typical for a domestic event, hams on the east coast had begun shifting their activity to the 40-meter band, but the bulk of activity was still on 20 meters. Callsigns of stations CQing were captured by several dozen CW skimmers across the US; timestamped skims are archived by the Reverse Beacon Network (RBN). In the hours before 2200Z, a sustained rate of over 400 CQs was being recorded each minute by RBN, as plotted on the left side of Figure 1.
I had been on the air since the NAQP’s starting gun at 1800Z, exercising my 2BSIQ (Two-Band Synchronized Interleaved QSO) skills. In the hour before 2200Z, I
