Because of the fact that SFI (solar flux index) was very high yesterday (213) – December 19th, 2014 – with high sun eruption activity – D level of Ionosphere was highly ionized – Dellinger effect happened in Central Europe (but surely not only there).
I switched up my rig on 3.5 MHz band (CW part) at 18.45 UTC (deep dark in my QTH) and I heard nothing. At first I looked for some error of my rig or antenna. But everything was OK. So I looked at last Ionogram of Ionosphere Observatory Pruhonice near Praha (via Internet). I saw that no reflection from the Ionosphere was indicated and MUF (maximum useable frequency - 3000 km) was zero. Then I looked at the Ionogram of German Observatory in Kiel for checking. The result was the same (nil reflection). Everything became almost normal within an hour (at 19.45 UTC). Later I worked with Rob W1MK (CW, 3509.6 kHz) and a few European stations.
I registered a few Dellinger effects over my long HAM history of course but it has been the first case of the one since my new radio amateur activity (2000). Natural laws are still valid as I have seen ……
Ref.: 1) www.dictionaryofengineering.com/definition/
2) These pages: News - Ionogram