"Bill Jeffrey" wrote in message
...

There are many formulas for calculating inductance. All of them admit
to being approximations - but that's all you need. For example:

"For a coil of rectangular cross-section, of thickness t inches, length
l inches and mean diameter (average of inside and outside) d inches,
Hazletine's formula is L = 0.8d^2N^2 /(12d + 36l + 40t) uH"

Now if your entire coil, including the ferrite, is potted in epoxy, it
is a different situation. But I don't see that in any of your posts.

What if you took the dimensions of the existing coil, and guesstimate
down for winding cross-section because of the epoxy (I'm envisioning
a bobbin-shaped winding potted so you have a torus), plug in the
measured inductance, and it should give you _something_ !

Cheers!
Rich