More typically, the null is around 21-22 db as shown on this test while listening to the ground wave carrier of the YZA ndb (236kHz) located in Ashcroft, B.C., about 150 miles to the NE. As expected, the null is fairly sharp and the front / rear lobe, fairly broad.
One short check at dusk, produced nice signals from CJBC, the French-language station in Toronto. The past few nights it has been very strong but with a strong echo effect. I wonder if there is more than one CBC outlet here (860kHz), such as a low-power repeater, causing the echo.
At the same time, while still fairly light outside, WCCO in Minneapolis had a nice signal just before sunset.
No matter how poor conditions become, it seems that the Hinchinbrook (Alaska) ndb, 'ALJ' (233kHz), is always strong....looping north.
Hopefully conditions will only get better as the season progresses and I am able to give the loop a good workout....before it gets too windy!