(14) If the right side reading is HIGHER than the
(18) When the conditions in step 17 are met, the
left side, SUBTRACT the result obtained in step 12
control settings should be as follows: the "X" control
from the reading recorded in step 10 and adjust the
setting should be very close to the center position
variometer control in a CLOCKWISE direction to
(index marks aligned) and the "R" control should be
obtain the new value. If the right side reading is
plus or minus two turns from the center position as
LOWER than the left side, ADD the result obtained in
stated in step 5. There should be a good null present
step 12 to the reading recorded in step 10 and adjust the
(less than 7 mv).
variometer control in a COUNTERCLOCKWISE di-
rection to obtain the new value.
(19) If "R" control does not meet the requirements
of step 18, center the "R" control as per step 5 and adjust
R6 (inside the control box) for a good null. A minor
(15) Remove the magnetite tube.
adjustment of the "R" control should restore the "less
(16) Alternately adjust the "X" and "R" controls
than 7 mv" requirement of step 18.
until a minimum null is reached as indicated on the
(2) Failure to meet the conditions of step 18
indicates a defective head and or A-2 variometer mod-
ule. Replace either and repeat the complete procedure.
(17) Repeat steps 10 through 16 until the differ-
ence between the right and the left side is equal to or
less then + or -5 percent of each other.