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Fig. 1. Conductivity Temperature 

 Indicator (CTI). A. Deck-side 

 units. Top unit contains constant 

 voltage transformer, and meters for 

 monitoring voltage and frequency of 

 supply to instruments. Center 

 unit, temperature indicator. Bottom 

 unit. Conductivity indicator. Dials 

 read temperature in degrees centri- 

 grade and conductivity in millimhos, 

 respectively. Circular unit to 

 right of dials contain indicating de- 

 hydrating agent. Middle, four posi- 

 tion switch on each unit has three 

 calibrate positions and a "normal 

 use" position. Bottom row of con- 

 trolls are, right to left, fuse, powre 

 switch, power indicator light, and 

 switch to turn the balancing motor 

 on and off while keeping unit energized. 



■X 



Fig. 1. B. Underwater head. 

 Sensing elements and junction box sus- 

 pended on eight springs. Portion pro- 

 truding through top of cage is water 

 proof connector for MCOS-6 cable. 

 Entire unit below water proof connector 

 is oil filled, bellows on left prevent 

 pressure differential across case. 

 Conductivity cell on right, resistance 

 thermometer on leucite web on left. 



or knows of no instrument other than the STD and the CTI, the latter to be de- 

 scribed below, which exist in anything but pilot models. 



The Navy Electronics Laboratory at San Diego, California, is reported 

 to be building a salinity-temperature-depth recorder which uses a thermistor 

 for the thermal unit, and a conductivity cell of the same design as that used in 

 the CTI. There is no information available concerning the operating character- 

 istics of this instrument. 



A conductivity-temperature indicator (CTI) has been constructed by the 

 Chesapeake Bay Institute of The Johns Hopkins University. The instrument was 

 designed primarily for estuarine studies and so has a conductivity range to cov- 

 er salinity from °/oo to 35 °/oo and a temperature range of -2" to 32°C. The 

 instrument contains no depth measuring element. In relatively shallow estua- 

 rine waters depth can be estimated adequately by measuring the length and angle 

 of the lowering cable. The underwater element consists of a two electrode H- 

 type conductivity cell* and a nickel resistance thermometer. Temperature in 

 degrees Centigrade and conductivity in millimhos are indicated on a pair of four 

 digit counters mounted on the amplifier and servo mechanism housing. Pictures 

 of the instrument and a schematic drawing of the circuits are shown in Figures 1 

 and 2. Wherever possible, commercially available components have been used 



* - Conductivity cell manufactured by Kahl Scientific Instrument Corp. , El 

 Cajon, California. 



