3. Operation of Pressure-Sensitive Gage 



a. Calibration 



Perform the following steps in the given order for pressure- 

 gage calibration: 



a) Connect the strip-chart signal cable to the amplifier- 

 power-supply unit. 



b) Set the tide-capacitor switch to the "capacitor-out" 

 position (switch contacts closed) . 



c) Apply power to the recorder and the amplifier-power unit. 



d) Adjust the d.c. voltage out of each 60-volt power supply 

 to exactly 60 volts. 



e) Adjust the d.c. voltage out of the 6-volt power supply 

 to exactly 6 volts. 



f) Remove power from amplifier-power unit and strip-chart 

 recorder. 



g) Connect wave sensing-unit cable to the four binding posts 

 on amplifier-power-supply unit. Be sure that the color 

 code on the binding post has been carried to the same 

 color code on the Sanborn linear-differential transformer 

 inside the pressure-sensing unit. 



h) Set dial on the 10-turn variable resistor on the amplifier- 

 power unit to its counterclockwise (lowest resistance) 

 position. 



i) Apply power to amplifier-power unit and strip-chart 

 recorder. 



j) Adjust pen on the strip- chart recorder to center of 

 recording chart with lever on side of penmotor. 



k) Decide the maximum wave height to be recorded and divide 

 by two. 



1) Lower gage 1 foot into still water and readjust recorder 

 pen to center of chart paper with lever on side of pen- 

 motor. 



m) Lower gage into water one-half of the wave height expected 

 to be recorded. Value found in step k above. 



73 



