The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH
T-37 9turns 30awg = ~180uH

Perhaps there is a chart or something similar somewhere that I have
overlooked that will give me an idea.

The equation goes;

Turns = 100SQR(uH/Al) where Al is the inductance in uH per 100 turns)

and

15 = 100SQR(150/Al)

and (0.15)^2 = 150/Al

and

150/0.0225 = Al = 6666.

You have ferrite not powdered iron.

For Ferrite, it's just the conversion

Turns = 1000SQR (mH/Al) where Al = mH/1000 turns

15 = 1000SQR(.15/Al)

and
0.15/0.00225 =66 which looks like, (for T50 core) material 61

W4ZCB

and
0.15/0.00225 =66 which looks like, (for T50 core) material 61

And the T37 core, at 2200, looks like 75 material, look out for it's bulk
resistivity which is pretty low.

W4ZCB

and
0.15/0.00225 =66 which looks like, (for T50 core) material 61

And the T37 core, at 2200, looks like 75 material, look out for it's bulk
resistivity which is pretty low.

W4ZCB