It is formed of two interlocking rings: one with the transformer core and primary windings, much like a conventional toroidal transformer and the other with the secondary windings. The secondary is wound like in a typical toroidal transformer but with a very large diameter to reduce interwinding capacitance and undesired capacitive coupling of RF energy. The power from primary to secondary is transferred by inductive coupling. It is used for providing power to the aircraft warning lights and other devices on a mast radiatorantenna insulated from ground. In the Austin transformer the primary and secondary windings are separated by a large air gap, so that the high voltage and AM RF energy on the mast cannot couple into the low voltage lighting supply wiring, causing safety hazards and electromagnetic compatibility issues.
Griffith, B. Whitfield (2000). "Practical operation of the vertical antenna". Radio-electronic transmission fundamentals (2nd ed.). Sci Tech Publishing. p. 367. ISBN1-884932-13-4.
