I'm trying to understand something ...
You say useful coverage in a quiet area extends to the 150 µV/m contour. (IIRC, David Eduardo says coverage in an urban area only extends to the 10 or 15 mV/m contour. I'm not totally sure if that means a barely-detectable carrier, a totally noise-free signal (maximum legal modulation would physically blow out your eardrums, no modulation would be completely inaudible (assuming healthy ears) in an anechoic chamber) or something between, but I'm assuming based on his previous comments that it's more like the noise-free signal.)
So is that 150 µV/m signal in a quiet area supposed to be noise-free on a typical consumer portable radio, like a Tecsun PL-310, Sony SRF-M37W, etc (not including cheap/insensitive Coby radios)? What field strength in a quiet area would you say would be the limit for being able to detect a very faint signal (which of course is dependent on the quality of the radio and antenna used)?
Also I've looked at the FCC protection rules for licensed broadcast stations a little. As I understand it, Class A stations' groundwave contours are protected to the 100 µV/m contour by a factor of 26 dB. I understand that means that at that level, an interfering station's signal has to be at least 26 dB below the class A station, which would work out to about a 5 µV/m signal.
In a quiet environment on the surface of the earth (not in a screen room), what might be the reception quality of a 5 µV/m signal in the absense of other interfering stations? (I'm assuming a beverage antenna or other large loop antenna would be required to pick up that signal, if it's possible at all.) Also what might be the typical distance / groundwave field separation for co-channel 50kW ND class A stations (they're actually protected, IIRC, to the 50% 500 µV/m skywave contour), and what might their groundwave field be at the approximate location where the two Class A stations' signals are equal?
