Summer Static and the 25 Metre Band
Summer is the dull season on shortwave, or at least it is at this latitude. The nights are short, so the lower bands never properly open; the sun is high, so the D layer soaks up anything below about 7 MHz during the day; and every afternoon a thunderstorm somewhere within a thousand kilometres fills the bands with crashes of static that make listening to anything weak a chore. For most of June the log has three or four entries a week, all of them strong broadcasters I could have heard any day of the year.
The exception has been the 25 metre band, around 11,600 to 12,100 kHz. In the hour after sunset, roughly 19:30 to 20:30 UTC in early July, it has been reliably open towards the south and east. The log for the last fortnight includes a Turkish station on 11,815 kHz with music and news in English, a Chinese-language programme on 11,955 kHz that was so strong it overloaded the receiver until I switched the attenuator in, and on two evenings a weak but clear station on 11,735 kHz in what I think was Swahili, which would mean East Africa.
The static crashes are the real summer problem, and I have found two partial answers. The receiver has a noise blanker that chops out the sharp spikes before the audio stage, and on the worst evenings it turns an unlistenable band into a merely annoying one, at the cost of a slight hollowness in the audio. The other answer is simply to listen with the bandwidth narrowed to 3 kHz rather than the usual 6, which cuts the energy of each crash as well as the fidelity of the music. Neither is a cure.
Keeping a log through the quiet months has turned out to be worthwhile for a reason I did not expect. Next summer I will be able to compare, evening by evening, and say whether the band is behaving the same way or whether the slow decline of the solar cycle has changed it. For now the baseline is being written, three thin entries at a time, and the thin entries are the ones I would never have bothered with if the log were only for the good nights.