(1) Be sure NAVIGATION DRIFT dial (fig.1) of
(1)
Deenergize 115 vac, 400 Hz primary power
unit under test is secured to shaft of transformer B2 (fig.
circuit.
(2) Disconnect electronic voltmeter from barrier
(2) Install jumper wires between terminals J and
strip and disconnect and remove all barrier strip jumper
U, H and S, and H and N of barrier strip (fig. 2).
wires.
(3) Connect electronic voltmeter to terminals P
(3) Install jumper wires between terminals H and
and U of barrier strip with test leads.
S, J and T, and S and U of barrier strip.
(4)
Energize 115 vac, 400 Hz primary power
(4) Connect electronic voltmeter to terminals N
circuit.
and P of barrier strip with test leads.
(5) Observe electronic voltmeter and carefully turn
(5) Unlock NAVIGATION DRIFT dial lock (fig. 1)
NAVIGATION DRIFT dial for maximum indication on
and energize 115 vac, 400 Hz primary power circuit.
electronic voltmeter. If maximum indication cannot be
obtained, perform adjustment No. 1 in b below.
(6) Observe electronic voltmeter and carefully turn
NAVIGATION DRIFT dial to minimize indication on
(6) Check NAVIGATION DRIFT dial indication.
The dial should indicate 0 5. If dial indication is incorrect,
perform adjustment No. 2 in c below.
(7) Check NAVIGATION DRIFT dial indication.
The dial should indicate 0 + l/3 dial division.
b. Adjustment No. 1.
b. Adjustments.
(1) Disassemble dial lock (fig. 1) and turn
NAVIGATION DRIFT dial (five revolution maximum) to
(1) Set NAVIGATION DRIFT dial at 0 and lock dial
obtain maximum indication on electronic voltmeter.
(2)
Reassemble dial lock.
(2) Refer to figure 4. Loosen the three clamp
screws that secure case of transformer B2.
c. Adjustment No. 2.
(3) Observe electronic voltmeter and slowly turn
(1) Set NAVIGATION DRIFT dial at 0 and lock dial
case of transformer to minimize indication on electronic
(2) Refer to figure 4. Loosen the three clamp
(4) Tighten the three clamp screws that secure
screws that secure case of transformer B2.
case of transformer B2.
(3) Observe electronic voltmeter and slowly turn
12. Final Procedure. a. Turn the power switch of the
unit under test to OFF, and disconnect the equipment.
(4) Tighten the three clamp screws that secure
b. In accordance with TM 38-750 annotate and affix
case of transformer B2.
calibration DA Label 80 (U.S. Army Calibration System).
When the unit under test cannot be adjusted to within
11. Navigation Drift Transformer B2 Fine Position.
tolerance, annotate and affix DA Form 2417
a. Performance Check.
(Unserviceable Test Instrument or Standard) (reg tag).
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