Just stuck my head in the door of the Electromagnetics Lounge, but the coffee wasn't ready yet. Will be back...
In the meantime, the most important thing I look for in a loop design is the Effective Height, which is a measure of its signal collecting ability. This is 2 * PI * N * A * Q / lambda, and if I have the following correct:
N = 9T
A ~ 9 M^2 For a loop with 10 foot sides
lambda = 1000M for 300 kHZ
then the He for the loop would be approximately 0.5 * Q Meters.
Knowing what the actual Q is would give a rough idea of what to expect from this loop in resonant mode.
I see that you are using the amp/supply from the HF loop. This uses back to back tuning diodes such as NTE618. These devices, IIRC, have a guaranteed minimum Q of ~ 100 at 1000 kHz. In a tuning diode, the Q (at a given bias) is generally a close to linear function of frequency. My recollections of trying this type of tuning with the ferrite loop seemed to validate this, and that the diode Qs seemd to be significantly lower at NDB frequencies. Even so, if the diode Qs were around 30, the the He would compute out to be around 15M, which would not be too shabby.
If you could actually measure the Q from a screenshot, that would be cool and helpful.