Abstract: The housing includes a casting formed with a provided cavity for receiving and supporting therein a high frequency circuit fabricated on a ceramic substrate. A cover portion is adapted to be affixed to the casting to seal off the cavity. Both the cover and casting are made from an electrical conducting but acoustically dampening material. Rigid standoffs with rubber bumpers at one end extend from the cover portion into the cavity such that when the cover is affixed to the casting the bumpers forcibly engage and compress against the circuit substrate thereby constraining the substrate against the casting. The amount of compression of the bumpers is controlled to minimize circuit microphonics caused by external mechanical shock.