[G6Tanuki]

Of course some receivers used mechanically-variable spacing of the IFT windings so you could choose between a sharp peak, something a bit flatter/wider, or the double-humped wider bandwidth of overcoupling if you wanted hifi reception.

I also remember seeing something in a German marine radio where the two IF coils in a can were wound on ferrite pot-cores and largely screened from each other by Mumetal, but there was a mechanically-movable ferrite rod between them that could be rotated by a panel control to vary the coupling.