balun saturation

I've got an output balun saturating.
The core is a 2-hole core nickel-zinc ferrite.

The equation <see attached> calculates the saturation flux density for toroid where Ae is the effective area of the core. How do I calculate the effective area of a 2-hole balun. How else do I know the saturation point of a 2-hole balun?

Is there any software that does bifilar and trifilar baluns?

thanks,
GE

anyone?