Section VII
Paragraphs 7-7A to 7-7D
e. Connect Continuity Checker GRD test probe to
i. True magnetic bearing of target (BMAG) is
common connection of the three secondary (pick-up)
bearing (B) of step 7-7.f plus (index error o step
coils of the valve assembly (pin F of Field Tester
7-7.e (I1) minus error of step 7-7.h (I2), divided by
connector P2).
two) :
f. Use Continuity Checker CONT test probe to
( I1 - I2)
check continuity of secondary coils. When the CONT
B
G= B +
2
probe makes connection with pin A, B, or C of Field
MA
Tester connector P2, the meter shall indicate 10
to 52 ohms.
j. Replace Turntable with Monitor to be tested,
without moving Tripod. (See figure 7-2.) Sight target
g. Connect the GRD test probe to pin E of Field
with Monitor and set azimuth scale to bearing (BMAG)
Tester connector P2, and the CONT probe to pin D
of step
of Field Tester connector P2 with Tester switch
k. Rotate Monitor to headings of 0, 90, 180, and
S4 set to INDEX, to check continuity. The meter
270 degrees and record READOUT ERROR at each
shall indicate 500 to 3000 ohms.
heading. Subtract the indicator index error of step 2,
Part VII of table 7-2. Calculate monitor index error as
in step 7-7.e. This index error is the difference be-
tween the optical axis of the Monitor telescope and
the magnetic axis of the Monitor transmitter. This
error shall be equal to or less than 6 minutes.
Return variable resistor knob to OFF position
after each test, and before disconnecting
1. If this error exceeds 6 minutes, return Monitor
power cable. This will preclude possibilities
to depot for repair and calibration.
of magnetizing the valve assembly and causing
consequent inaccuracies in its operation.
7-7B. FIELD TESTER D-C CONTINUITY CHECK.
Ensure that the Tester is disconnected from any
Step 7-7.k shall be completed within 30
minutes of step 7-7.i to minimize errors
due to shifting of the earth's magnetic field.
7-7C. CROSS HAIR CALIBRATION. To determine that
a. Using Flux Valve Continuity Checker, (Contin-
the cross hairs in the telescope are vertical, per-
uity Checker, figure 2-1) connect power cable sup-
form the following operations:
plied with Continuity Checker to pins 1 and 2 of
the rear panel 8-pin connector and to a 115-volt
ac, 400-cycle, single phase power supply.
a. Mount the magnetic azimuth reference detector
with the telescope up on the Turntable and tighten
mounting screws.
b. Carefully level the Turntable, noting that the
bubbles remain centered for complete rotation of
Never use a d-c ohmmeter to check valve
the Turntable.
assembly continuity.
c. Sight a vertical target a convenient distance
away. The recommended target is a plumb bob line;
b. Connect test leads supplied with Continuity
however, a corner of a building may be used.
Checker to GRD and CONT connectors on front
panel.
d. The cross hair shall coincide with the line over
c. Turn Continuity Checker selector switch knob
the entire visible distance.
to A-CONT position.
d. Connect uninsulated portion of Continuity Checker
test probes together and turn variable resistor knob
check the vertical tracking of the magnetic azimuth
until fullscale reading, zero ohms, is indicated on
reference detector telescope, perform the following
meter.
operations:
a. Mount the Monitor on the tripod and carefully
level.
b. Using the target determined in 7-7C.c, sight a
point 5 degrees below horizontal with the vertical
Handle probes by insulated portion only.
scale of the Monitor and mark this point.
7-10
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