minimum. Depth checks can be obtained using ship's depth finding equipment. 

 Another method of checking depth would be a comparison with the EDO reading. 



The following procedure is used for determining counter constants for Inverted 

 preset reset counter using a specific VIbrotron , 



1 . Connect VIbrotron amplifier output to inverted preset reset counter Input 

 "A" and oscillator mixer input. Connect (oscillator mixer) output to counter input "B." 



2. Allow counter and VIbrotron to warm up for 1 hour. 



3. Set "Freq. Std." toggle switch to "External." 



4. Set MULTIPLIER to 10000. 



5. Apply atmospheric pressure to VIbrotron and make display read 00000 

 by adjusting RESET NUMBER. 



6. Apply 100 psi to VIbrotron with dead weight gage. Make a note of 

 display number after it repeats itself. 



7. Divide 68.6 meters by displayed number. 



8. Enter the quotient into MULTIPLIER. 



9. Return dead weight gage to zero and make display read 00000 by 

 adjusting RESET NUMBER. 



10. Test 50 psi and 100 psi to see If the display reads 34.3 meters and 68.6 

 meters, respectively. 



n . Counter is now set to read transducer depth in meters and tenths. DO 

 NOT MAKE COUNTER READ KEEL DEPTH. 



D. Wave Profile 



The inverted EDO fathometer recorder, which is utilized for wave recording 

 measurements, does not require calibration. To check satisfactory operation of trans- 

 mitter and receiver, a suitable zero mark on the 0-70 Phase must be evident on the 

 chart recorder. The time period between consecutive open air transmitted pulses can 

 also be checked, this should be .112 second (87 meters) on "Feet" range or .679 second 

 (523 meters) on "Fathoms" range. 



18 



