I believe you are correct that it's simply additional signal strength drowning out the internally generated hets on the PL-380.
I tried the mini loop with my Satellit 800. It can provide a good signal boost, since the ferrite bar in the Sat 800 is only about 3.5" long. Unfortunately, the tuning of the loop is very touchy with this particular radio, especially on the high band. I don't notice this degree of difficulty when using the mini loop with the PL-380 or DT-400W. I generally use my Quantum QX Pro with the Sat 800.
If Tecsun would add a dedicated 10 kHz tuning mode to the PL-390, I'd pick one up. The lack of this feature is the one thing that annoys me the most about the PL-380, because it makes bandscanning needlessly difficult. Even my old Eton E100, which is made by Tecsun, has 10 kHz up/down slewing buttons.
--- In firstname.lastname@example.org, "Kevin S" <satya@...> wrote:
doesn't register the loop when they are adjacent to each other (loop in the receiver ferrite end-fire) is similar to other receivers that I have used. The Quantum Stick is often not "seen" by receivers in this orientation, for whatever reason.
guessing, but I think it is because the internally-generated tones are
overcome by the extra signal, since it keeps getting better and better as the size of passive loop increases, especially on weak stations. This leads me to believe that the noises are coming from the circuit board, somewhere near the ferrite. Also, the hets are much better (quieter) on the PL-390 with its larger ferrite, so apparently the additional signal from the ferrite antenna means that the hets are more "drowned out".