Something touched me today to compare the inverter circuits in the ZX Spectrum and Enterprise.
You could say "Find the differences"
I managed to recreate the coil to ZX Spectrum with full success (see the picture).
I have an undamaged coil from disassembly to the EPower module.
When I find some free time I will measure its, unroll and count the scrolls.

The windings are wound in wire in enamel with a diameter of 0.25 mm.
The primary winding (legs 1-2) is wound on the core first and consists of 12 windings.
Secondary winding (external, legs 3-4) has 60 windings.
In fact, the beginnings of the windings are on legs 2 and 4.
Both windings are wound in a clockwise direction and they ends are, respectively, on legs 1 and 3.
Unfortunately, I was unable to measure the inductance. I do not have a sufficiently accurate measurements (range of micro Henr).

The ZX Spectrum  has a coil with transformer gear 1:3. In EP is 1:5.
Apart from this difference, it is very similar.