| 摘要 |
An apparatus (50, 100, 150) for sensing a surface level (20) of fluid (12) includes a generally cylindrical central conductor (16, 102, 152) for connection to a pulse signal source (26) with a reduced diameter end (28, 104, 154) and an opposite end (24, 124, 168); a generally tubular outer conductor (14) concentric with the central conductor for connection to the pulse signal source and having one open end (32) adjacent the central conductor reduced diameter end and an opposite open end (18) adjacent the central conductor opposite end, the central conductor and the outer conductor forming a transmission line for pulse signals generated by the pulse signal source and a cavity (C) between an interior wall surface of the outer conductor and an exterior surface of the central conductor; a non-metallic seal (54) mounted at the outer conductor open end for sealing the cavity, the central conductor reduced diameter end extending through a central aperture (52) formed in the seal; a circuit board (58) for mounting the pulse signal source and being electrically connected to the central conductor reduced diameter end and to the outer conductor one open end; and either a socket (68) attached to the outer conductor one open end or a collar (112) attached to the circuit board for maintaining the seal in sealing contact with the outer conductor one open end and the central conductor reduced diameter end to prevent the fluid in the cavity from contacting the circuit board.
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