A high frequency device having a shield casing with the interior divided into small sections by shield plates, and with circuit blocks of a high frequency circuit in the respective sections including substrates with circuit components on the upper surface with terminals extending through the substrate to a printed circuit on the lower surface. A feedthrough capacitor is mounted in the casing or in the shield plate, or both, in a level corresponding to the level of the substrate, such that the feedthrough terminal of the capacitor extends adjacent the printed circuit, and such that, when the device is immersed in solder to solder the terminals of the components to the printed circuit, the feedthrough terminal of the capacitor is also soldered to the printed circuit and the capacitor itself is also soldered to the casing or the shield plate. Further, steadying fingers are provided around the fixing hole portion in the casing or plate, and these are spaced around the periphery of the fixing hole portion so that the two fingers nearest the bottom edge of the casing or plate are a maximum distance from the edge, so as to maximize the resistance of the casing or plate to distortion when the fingers are bent laterally from within the fixing hole portion.