Figure 9-1. GEK Miulel V rt 



howiiiK liicati 



upper left-hand corner of panel) clockwise all 

 the way, and then return it to the point where 

 the pen just ceases to quiver. 



9-19 Vertical Intensity (H,)— Set the 

 VERTICAL INTENSITY knob, marked H, 

 OERSTED, to the value of the nearest standard 

 isodynamic line shown on H. O. Chart No. 

 1702 for the position of the ship at the time of 

 the observation. 



9-20 Wave Signal Suppression. — If sea 

 conditions cause the recorder pen to oscillate 

 with more than a 15 cm. /sec. range, increase the 

 FILTER RESISTANCE di&\ setting from zero 

 until the wave signals are sufficiently suppressed 

 to give a readable trace. Do not suppress the 

 wave signal excessively as it will make it too 

 sluggish. An oscillation with a range of about 

 15 cm. /sec. is best. Log the total suppression 

 used as indicated on the FILTER RES IS T- 



H. O. 607 



ANCE dial. When the circuit is secured after an 

 observation make sure that the dial is turned 

 to zero position and move the SUPPRESS 

 WAVE SIGNAL switch to the CAP. SHORT 

 position. This short-circuits the capacitors 

 and releases any accumulated dielectric strain. 

 In rough weather when heavy wave signal 

 suppression is needed it is well to examine the 

 wave signal without suppression from time to 

 time. To do this move the RC switch mo- 

 mentarily to the i?C=0 position. In case a ca- 

 pacitor is faulty or the sea is on the beam, the 

 suppressed signal will not coincide with the 

 densest part of the unsuppressed signal. If a 

 change of FILTER RESISTANCE has no ef- 

 fect, the asymmetry is due to the direction of the 

 waves. The amount and sign of asymmetry 

 and its probable cause should be noted on the 

 log sheet. 



89 



