A support frame for an electrical transformer assembly, comprising two loop-shaped parts, each loop-shaped part having a plurality of limbs, each limb having a peripheral recessed portion in which a primary electrical coil is mountable, and at least one secondary coil is mountable in piggyback on the primary electrical coil, one limb of each loop-shaped part having a straight section. The frame also includes an adjustable attaching means for attaching one of the loop-shaped parts with respect to the other loop-shaped part and adjusting a distance therebetween, so that only the straight sections are adjacent and form a central leg, the central leg being for receiving a magnetic core distinct from the attaching means. The frame provides a means and a method to efficiently secure adjacent windings in a circular core transformer kernel.