Abstract: The invention relates to a compact and cost-effective diode-split high-voltage transformer for high voltages of, in particular, above 20 kV, in which the high-voltage winding lies in chambers of a coil former underneath the primary winding and which contains elements by which the electric field between the coil former and the core is reduced in order to avoid corona effects. These elements include, for example, a conductive coating of the surface of the inner cavity of the coil former, which coating preferably comprises colloidal graphite. The conductive coating may also be realized by a metallized plastic film which is wound between the core and the coil former. Alternatively, the cavity between the core and the coil former may be filled with a material whose relative permittivity ∈r is distinctly greater than that of air. The use of a larger number of diodes is also possible for reducing the electric field.