COMPENSATION CHECK-OFF LIST 77 



the H-M slide wire resistor at the midposition and 

 cautiously shorting out sections of series resistance 

 in the H-M control circuit. The refined adjustment 

 is then obtained by revising the setting of the H-M 

 slide wire resistor. See art. 119) . 



(d) Be sure that final setting would not permit more than 



1.4 amperes (1.0 amperes for "T" coils) to flow 

 through the variable control resistor, at maximum, 

 degaussing coil current. This is approximately 

 equivalent to 2.2 volts per winding across H-M com- 

 pass coils of the type "B," "G," or "K" installation, 

 and 4.8 volts per winding across the H-M compass 

 coils of the type "T" installation. If fixed resistors 

 are in series with variable resistor, maximum cur- 

 rents are smaller, as shown in chapter XII. 



(e) Kepeat (&), (c), and (d) for all other degaussing coils 



(F, Q, A) individually, while dip needle is still 

 balanced. Correct each with H-F, H-Q, and H-A 

 coil windings, respectively. 



2. Type "B" compensating coil procedures. {Cardinally 

 mounted type "7"' coil procedure is the same., except for 

 voltage limitations as noted in art. 129. Heeling adjust- 

 ments for any type coils are made as in Section B-1 of this 

 Check-off list) : 



(a) Eeplace dip needle with regular compass. 



(b) Deflect compass card to 090° or 270° heading, which- 



ever is closer, with all degaussing coils secured (art. 

 125). 



(c) Energize M degaussing coil to maximum operating 



current, and note deviation of the compass. (See 

 note at end of art. 108.) 



{d) Adjust current in the B-M (Flinders bar) compass 

 coil until compass returns to original position. If 

 the compass is further deviated by increasing the 

 B-M coil current, the B-M coil polarity must be 

 reversed. ( Coarse and fine adjustments are achieved 

 as noted under Heeling Coil Procedure) . 



{e) Difficulty may be experienced in obtaining sufiicient . 

 correction if the Flinders bar is short, but may be 

 achieved by the use of additional windings or coils. 



(/) Be sure that final setting loould not permit more than 

 1.4 amperes to flow through the variable control re- 

 sistor, at maximum degaussing coil current. This 



