TM-9-1240-401-34&P Technical Manual for M109 Telescopes and Mounts Download
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5-55 TM 9-1240-401-34&P 6 7 8 9 10 11 Measure distance from cap (5) to mark on wall in inches (centimeter). Multiply the distance found in step 6 by 0.30350 (tangent of 300 roils). Place tape (6) above and below mark, at a dis- tance determined in step 7. Rotate elevation knob (7) from stop to stop. The reticle must follow plumb line (1) within 0.5 mil. The line of sight must elevate, or depress, no less than 300 roils in each direction from center. If line of sight travel is not within the 300-mil limits in each direction, adjust elevation knob (7) (ref. para 5-13). If the reticle does not track the plumb line (1) within 0.5 roil, send M117/M117A2 panoramic telescope to depot for maintenance on dove prism assembly. i. AZIMUTH ERRORS (800-MIL STEPS) AND BACKLASH (AZIMUTH MECHANISM) 1 2 3 NOTE Azimuth reading shall be made at 800-mil in- crements through one full revolution of the azimuth fixture ring (1) in each direction. Rotate azimuth fixture ring (1) counterclockwise to 800 mils. Rotate azimuth knob (2) clockwise until retitles coincide (ref. para 5-26c). If coincidence point is overtraveled, rotate azimuth knob (2) counterclock- wise one-half turn past coincidence point and re- peat this step. Azimuth counter (3) should increase by 800 mils ± 1.0 mil and reset counter (4) should increase by 800 roils ± 1.0 mil. Record readings.