Electronic Circuits and Projects Forum

I could use some advice concerning microwave oven transformers.

I know these MOTS tend to saturate under low load and this causes energy wasted as heat in the primary.

I want to remove the step up secondary and replace it with a 12 AWG step down to about 28VAC. That may require around 28 to 35 turns of wire from general MOT winding data.

My issue is this. I want to reduce the losses due to MOT saturation. I can separate the E and I sections of the core. Would it be acceptable to add a small air gap between the E&I sections of the core to limit the saturation of the core? How would this affect my output....would I need more wire turns etc? I'd like to see perhaps 15 to 20Amps full load output,5 V drop. The MOT is from a 1.2KW microwave. I understand adding more soft iron to the core can also offset saturation. If I build layers of 2 mm thick headless nails (individually dip varnished) stacked to extend the E core, how shall I calc the mass of iron nails I need?

Adding more windings to the Primary may be possible, but it looks kinda tight.

Thanks for any advice.