ARMY TM 9-1290-262-24&P
MARINE CORPS TM 00476C-24&P
AIR FORCE TO 49A7-3-72/74
CIRCULAR ERROR TEST
NOTE
Circular error can be present in aim-
ing circle even though worm and
worm gear mechanisms operate
smoothly and do not have excessive
backlash. Error is due to poorly
spaced worm gear teeth.
Set azimuth ring (1) of test fixture to zero.
1
Rotate azimuth knob (2) to set aiming
2
circle azimuth index and micrometer scale
to zero.
3
Using orienting knob (3) quick release,
direct aiming circle elbow telescope line-of-
sight into collimator.
4
Using orienting knob (3), adjust aiming
circle to superimpose elbow telescope
vertical reticle line on collimator vertical
reticle line.
5
Using elevation knob (4), superimpose
aiming circle horizontal reticle line on colli-
mator horizontal reticle line.
Offset test fixture azimuth ring (1) 800 mils
6
counterclockwise.
Rotate azimuth knob (2) to set aiming
7
circle to 800 mils.
Look through elbow telescope eyepiece.
8
Error between aiming circle verticle reticle
line and collimator vertical reticle line
should not exceed 0.7 mils. If tolerance is
exceeded, refer to azimuth worm backlash
test and adjustment, page 3-39.
Repeat steps 7 and 8 at 800-mil intervals
9
until the complete circle is made.
