Abstract: A piezoelectric resonator (1) consists of a piezoelectric reed (2) encased in a housing composed of a cap (7) and a base (8). The resonator (1) is placed in a thermostatically controlled containment (10). The thermostatically controlled containment (10) consists of an inner cell (40) which is screwed into an outer cell (30). These cells (30, 40) each possess sides (34, 44) and a bottom (35, 45). A thermal seal (16) is inserted between the bottom (35) of the outer cell (30) and the bottom (45) of the inner cell (40). The cap (7) of the resonator is soldered over its entire outer surface to the sides (44) and to the bottom (45) of the inner cell (40). The thermostatically controlled containment (10) is placed in a secondary containment (21). A narrow space (22) separates the two containments (10, 21), and the surface of the contact between the two containments is as small as possible. The invention is used for ultrastable on-board oscillators.

Abstract: The subject of the invention is a high frequency bandpass amplifier with adjustable impedance, in particular for a high frequency quartz resonator. It includes a transistor T connected in common base the emitter of which is connected to ground by a resistive divider bridge (R.sub.2, R.sub.1) the mid-point of which forms the input of the amplifier. The collector of the transistor (T) is connected to ground by a parallel circuit (LC) having one inductive side (L) and one capacitive side (C), a mid-point of the inductive side (L) or of the capacitive side (C) forming an output (s.sub.1 or s.sub.2) of the amplifier (A). The base of the transistor is biased and connected to ground via a capacitor (C.sub.3) ensuring common base operation in the pass-band of the amplifier. The invention also relates to an oscillator of transmission type including such an amplifier and a resonator (1) connected between the input (e) and one output (s.sub.1 or s.sub.2) of the amplifier (A).