TM 5-6675-250-20
2-16. DETERMINATION OF AZIMUTH VALUE FOR REFERENCE MIRROR (Continued)
L O C A T I O N / l T EM
A C T I ON
R E M A R KS
SERVICE (Continued)
u.
Place the MODE SELECT switch (15) to GC
(gyro compass) (16); verify that the GYRO
SYNC indicator (17) illuminates within two
minutes, at normal ambient temperature
(above ± 15°F).
During the first azimuth determination on a new site the operator should in-
sure the follow up index mask does not remain at either end of the servo
operating range. Continuous operation of the instrument in this condition
c o u l d c a u s e e x c e s s i v e w e a r o f t h e s e r v o g e a r t r a i n s l i p c l u t c h . T h is
situation can exist in areas of excessive magnetic anomalies which cause
the GRU to be preoriented in excess of 40 degrees of true north.
2-80
