Abstract: A hermetic enclosure assembly having a metal header cover with interior and exterior portions and defining a plurality of apertures. A header body of rigid plastic material is adhered to and fills a substantial part of the interior portion of the header cover. A plurality of conductive leads protrude through the apertures, and bushings surround the conductive leads at the interior and exterior portions of the header cover where the pins protrude. A metal header casing is adhered to the metal header cover such that the interior portion of the header cover is completely enclosed. The assembly provides a minimum of plastic located exteriorly of the assembly and a maximum located interiorly.

Abstract: A process for making an encapsulated electrical insulation system such as a transformer which includes a porous fiber material filling. The system is vacuum baked at a temperature range of 100.degree. C. to 155.degree. C. for at least four hours, and is then vacuum impregnated with a mixture of a modified bisphenol A epoxy resin hardener comprising various acid anhydrides plus promoters. Pressure is then applied to the system of 1,000 psi. of nitrogen at 80.degree. C. for 2 to 12 hours. Thereafter, the temperature is increased to 110.degree. C. for 2 to 12 hours. The system is then cured at 135.degree. C. for approximately 12 to 24 hours. To minimize corona, shields are placed in selected portions of the transformer, the shields having edges formed into radii ends to avoid points at which corona would normally tend to concentrate. Also, the transformer is wound using ultra-clean components to obtain a transformer package that is free from impurities prior to impregnation.

Abstract: A bidirectional filter circuit having an input and an output and substantly constant input and output impedance characteristics over the desired frequency range. A low-pass filter network is connected between filter input and output and has identical low-pass filter half sections cascaded back-to-back with a symmetrical all-pass network interposed therebetween, the all-pass network providing isolation between the low-pass filter half sections and the desired terminating impedance therefor. First and second identical compensating networks are respectively connected to the filter input and output and have reciprocal characteristic functions with respect to the low-pass filter half sections to compensate for impedance changes in the low-pass filter half sections over the desired frequency range without affecting amplitude characteristics thereof.