Converting a stand up PT to a laydown

[Helmholtz]

Positioning the laminations of PT and OT at right angles is a good rule. But there are (at least in theory ) different ways to achieve this. The best orientatation is with laminations at right angles AND core center leg not pointing at the other transformer. Reason is that external fields are strongest in the direction of the center leg. Of course increasing distance also helps.

[Chuck H]

The best orientatation is with laminations at right angles AND core center leg not pointing at the other transformer. Reason is that external fields are strongest in the direction of the center leg.

I assume you mean that the lamination cores should (ideally) not be on a perpendicular plane? But rather, some degree of offset/diagonal?

[Helmholtz]

The method I am proposing requires to know the orientations of the coilformers/center legs. The centerline through the coilformer defines the (main) magnetic axis. I suggest to orient the transformers in a way that one magnetic axis is horizontal and the other is vertical.

I am aware that depending on transformer construction/mounting this method may not be applicable (without major modifications).