Transducers. Both the DE-719 and DE-719B are designed to use 208-kHz transducers with a connecting cord of a premeasured length and known electrical characteristics. The existing units are equipped with the 2445 AD (or 200 T5D) narrow beam transducer. The 2445 AD's 8-degree half-power beam angle results in the beam covering a lane on the seafloor approximately one-sixth of the water depth. The optional 7245 208-kHz very narrow beam transducer has a 2.5-degree halfpower beam width. The more narrow the beam width, the more precise the depth reading, especially in very deep water or steeply sloped areas. The wider beam width offers the advantages of "seeing" a greater proportion of the seafloor to locate obstacles or high points. The 2445 AD is quite adequate for our survey work. Replacement 2445 AD transducers are very expensive. The 719 and 719B will work with other transducer types as long as they have the same electrical characteristics. The 200 T5D is a generic replacement. When ordering replacements, be sure to specify the slug style Cannon J12-3 and connecting sequence, Red, Black, White. An alternate 50-kHz wide-beam transducer will see a seafloor lane approximately equal to the water depth. The wider beam makes precise depth readings difficult but would penetrate the seafloor surface slightly.
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