Rich, I'm curious - what value does the PL-310 show for KHMO?
My PL-606 and PL-398BT both show 81-82 dBu (sorry can't type the greek mu char on my SGH-T699) on 760 KFMB nighttime, which is about 136 mV/m here. On 1170 KCBQ, which is about 132 mV/m, they show about 80-81 dBu. BTW KCBQ uses MDCL - the dBu is the max that shows during "silent" periods in talk shows. The fields were derived from the groundwave graphs, distance, field in my direction, m3 map's conductivity, etc.
I have several stations that I often see hitting peaks around 58-64 dBu on a nearly nightly basis. These include 720 KDWN, 740 KCBS, 840 KXNT and 1580 KMIK. Would these be, I'm thinking, around 10-20 mV/m or so? When they are peaking, their signal quality is pretty much as clean as my local stations.
BTW one thing that could skew it - I notice that once I get above around 80-84 dBu, my Tecsuns start desensing. For example, I might first tune to 760 during a silent period and it shows 84 dBu, then when someone starts talking it drops to like 81 or so. (KFMB doesn't use MDCL.) Also, it doesn't start staying above 90 dBu until I'm within about ¼-½ mile of the site. (At home I'm 7.3 miles away.) I'm thinking there's potentially a few decades of dB of desense when indicating in the 80s dBu, especially as you get closer to the transmitter. Another example - KSDO indicates 50 dBu near KCBQ's site, but rises to the mid 60s or so when I'm a mile or two southeast of there.
