5266 HYDROGRAPHIC MANUAL PaGE 488 



Table 14. Parts and circuits of Dorsey Fathometer No. 3 referred to in tables 16 and 17 

 (The numbers 1 to 67 are assigned for reference purposes only and have no other significauce. They do not refer to terminal posts. 



Indicator 

 I. Keying. 



A. Photoelectric tubes. 



1. soundings once every revolution of the 20-fathom index disk. 



2. soundings every alternate revolution of the 20-fathom index disk. 



3. soundings once every revolution of the 100-fathom index disk. 



4. soundings every alternate revolution of the 100-fathom index disk. 



5. soundings once every revolution of the 1,000-fathom index disk. 



B. Exciter lamps. 



6. associated with 1. 



7. associated with 2. 



8. associated with 3. 



9. associated with 4. 



10. associated with 5. 



C. Thermionic tubes in keying amplifier. 



11. type 6F5 (vacuum triode). 



12. type "885 (gaseous triode). 



13. type 2 AS (vacuum triode). 



14. type 807 (vacuum pentode). 

 II, Indicating. 



A. Index neon tubes. 



15. located behind 20-fathom index disk. 



16. located behind 100-fathom index disk. 



17. located behind 1,000-fathom index disk. 



B. Type 885 tube circuits to flash index neon tubes. 



18. associated with 15. 



19. associated with 16. 



20. associated with 17. 



III. Rectifier circuits. 



A. Positive, furnishing 



21. polarizing voltage for 15, 16, and 17. 



22. plate voltage for 18, 19, and 20. 



B. Negative, furnishing 



23. bias voltage to 18, 19, and 20. 



24. hydrophone current. 



IV. Functional switches. 



[In describing these switches, the wafers are considered in order from top to bottom when the front of the indicator cabinet is fully 

 opened. And for each wafer, the common arm which connects to the switch points on the left-hand side of the wafer (L) is listed 

 first. This common arm is just to the right of the supporting columns.] 



A. Depth-selector switch — connecting 



25. (L) 500 volts d-c to 12. 



26. (R) 6.3 volts a-c to 6, 7, 8, 9, or 10. 



27. (L) plate of 11 to grid transformer of 12 or 1 megohm load resistor. 



28. (R) 87 volts d-c to 1, 2, 3, 4, or 5. 



29. (L) grid of 13 to plate of 12 or 1 megohm load resistor. 



30. (R) (blank). 



' \ \ plate voltage (22) to combinations of 18, 19, and 20. 

 62. (Kl 



