Abstract: Printed circuit boards (PCBs) are disclosed comprising a support which on a major side carries circuit components in a desired design and on a second major side carries the soldered wires corresponding to said circuit components. Manufacturing of the PCBs is carried out by producing respective designs of the component and soldering sides as labile electrostatic images on which conductive metallic powder (toner) is applied. The so obtained images are printed on respective insulating sheets, one with the component side design, and another with the solder side design. The thus printed sheets are fixed on the PCB support, and the conductive designs are treated to increase the thickness of the design.

Abstract: A dual mode filter has a hollow cylindrical longitudinal outer body which is divided by transversely extending disk-like separation walls into a plurality of internal cavities. At least one coupling opening in each separation wall permits coupling of energy from one cavity to another. Said coupling opening being preferably an arcuate opening, in each separation wall, which extends along a constant radius at the outer periphery of the separation wall and over a limited angular span. When the openings are two, they are spaced 180.degree. apart, i.e. opposite one another. Adjacent separation walls are rotatably displaced 90.degree. with respect to each other so that their respective coupling opening(s) is (are) misaligned by 90.degree.. One respective adjustment screw is provided for each separation wall which penetrates through a hole in the outer body into one of the coupling openings in the given separation wall.