Frequency-output conductivity sensor, for use on SBE 25 and 25plus Sealogger and SBE 9plus profiling CTDs or for fixed-site applications.
The SBE 4 conductivity sensor is a modular, self-contained instrument that measures conductivity from 0 to 7 S/m, covering the full range of lake and oceanic applications. The sensor has electrically isolated power circuits and optically coupled outputs to eliminate any possibility of noise and corrosion caused by ground loops. Interfacing is also simplified by the square-wave variable frequency output signal (nominally 2.5 to 7.5 kHz, corresponding to 0 to 7 S/m). The sensor offers improved temperature compensation, smaller fit residuals, and faster turn-on stabilization times.
Because of the SBE 4’s low noise characteristics, hybrid frequency measuring techniques (used in Sea-Bird’s CTD instruments) provide rapid sampling with very high temporal and spatial resolution. The SBE 4 is ideally suited for obtaining vertical data with lowered systems or horizontal data with towed systems. Because of its small size, it is especially useful for moorings, portable CTD systems, or through-the-ice work.
The SBE 4C is a primary sensor for the SBE 9plus, 25, and 25plus profiling CTDs; it has a quick-disconnect fitting to simplify plumbing to the CTD pump. The SBE 4M, intended for long-term moored deployments, is supplied without the quick-disconnect fitting.