如何计算出它的圈数？

Turns ratio:                         W1:W2=1:1

Inductance (1-4)(8-5):    27.0mH±10%

DCR (1-4):                            1.4Ω Maximum

Material:

BOBBIN:                               EF20, Horizontal, 2 sections, 4 pins

CORE:                                    EF20, Mn-Zn

Wire:                                     (W1, W2) Ф0.30mm (would this be enough for 650mA rated current, please suggest)

GLUE:                                    Araldite.

Mechanical Dimension: in m  所有的东西我都已经知道了！请教一下各位大哥！我应该如何的计算出它的圈数啊？麻烦各位了！很急！小弟感激不尽啊！