ATN PVS-7 Operator's Manual page 49

(Figure 2-4). press button slightly with thumb until proper brightness
is obtained. the image should appear as shown in Figure 2-12.
Figure 2-12. View Through Installed Compass
NOTE
Increase brightness slowly: if brightness is increased too quickly,
excessive brightness may burn a temporary image into the image
intensifier. The goggle must be focused at or near infinite for proper
compass operation.
4. the compass readings should change when you move your head
from side to side. rotate or tap compass slightly to ensure compass
is operating correctly. Hold the pVS-7 in a level position to assure
live rotation of the compass scale.
WARNING
THE COMPASS ILLUMINATOR CAN BE SEEN BY OTHERS USING
NIGHT VISION DEVICES.
NOTE
The compass reading is the magnetic North, not true North. The
compass reading is within 2° of correct absolute magnetic bearing.
Compass readings with a mounted PVS-7 (head mount or helmet
mount) can be up to ±15° of correct absolute, magnetic bearing.
This occurs most in the East (90°) to West (270°) and less in the
North (0°) to South (360°) reading. If the compass is inadvertently
magnetized this could cause an additional 15° error.
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