Abstract: An ultrasonic measurement instrument comprises a housing including a pair of spaced apart legs to define a gap therebetween. Each leg includes an interior cavity. An ultrasonic circuit comprises a transmit circuit for driving a transmit crystal receive in the interior cavity of one of the legs and a receive circuit for receiving signals from a receive crystal in the interior cavity of the other of the legs. A measurement circuit is connected to the ultrasonic circuit to periodically generate pulses in the transmit crystal and to sense pulses from the receive crystal to detect presence of a material in the gap. A self test circuit is operatively associated with the measurement circuit and electrically connected to the ultrasonic circuit for periodically testing operation of the ultrasonic circuit.

Abstract: An ultrasonic point level measurement instrument comprises a measurement circuit and a transducer. The transducer transmits and receives acoustic signals under control of the measurement circuit. An improvement in the transducer comprises a transducer housing including a pair of spaced apart legs to define a gap therebetween. Each leg includes an interior cavity. A pair of crystal assemblies each comprise a crystal mounted to a circuit board. The circuit board includes conduction paths for connection between the crystal and a terminal pad. Each crystal assembly is received in the interior cavity of one of the legs with the circuit board spacing the crystal from walls of the leg. A pair of cables are each connected between the measurement circuit and the terminal pad of one of the crystal assemblies so that the measurement circuit detects presence of a material in the gap.

Abstract: A process control instrument comprises a control for generating or receiving a high frequency signal. A waveguide comprises a cylindrical housing closed at one end by a rear wall. A loop launcher is operatively connected to the control and comprises a wire having a first straight leg electrically connected at one end to the control and extending into the waveguide a first select length. A second straight leg is connected at one end to the rear wall and extends into the waveguide a second select length, greater than the first select length. A curved middle section connects the other ends of the first and second straight legs. An antenna is operatively coupled to the waveguide.