TB 9-6625-2089-24
(25) Adjust CHAL AUX MOD DLY control fully ccw. Delay will be 0.05 μsec or less.
(26) Adjust CHAL AUX MOD DLY control fully cw. Delay will be 0.4 μsec or greater.
b. Adjustments
(1) Adjust A7R15 (main) (A7R4-AUX) for 0.80 μs (R).
(2) Position CHAL AUX MODE DLY control to detent and loosen set screws.
Adjust set screw center of knob to 0.2 μs as indicated on oscilloscope. Retighten set screws
in knob.
12. ISLS Accuracy
a. Performance Check
(1) Connect equipment as shown in figure 2.
(2) Position switches as listed in (a) through (c) below:
(a) CHAL INHIBIT to ISLS ON.
(b) MEASUREMENT FUNCTION SELECT to PRF CHAL.
(c) CHAL WIDTH SELECT to 0.25.
(3) Oscilloscope CH1 will display three pulses. Measure pulse spacing from leading
edge of first pulse to leading edge of second pulse, using timing markers on CH2 as a
reference. If pulse spacing is not between 1.95 and 2.05 μs, perform b (1) below.
(4) Adjust oscilloscope controls as necessary to measure width of second pulse at the
50 percent amplitude point, using the 0.1 μs markers. If pulse width is not between 0.75 to
0.85 μs, perform b (2) below.
(5) Set CHAL MODE SELECT switch to 4A and PRF SELECT switch to X1/2.
Adjust oscilloscope controls as necessary to display 29 pulses. Measure pulse width of fifth
pulse at 50 percent amplitude point, using 0.1 μs markers. If pulse width is not between
0.45 and 0.55 μs perform b (3) below.
(6) Using technique of (3) above, measure pulse spacing from leading edge of first to
fifth pulse. Pulse spacing will be between 7.93 and 8.07 μs.
(7) Vary AUX ATTEN control while observing oscilloscope, only the fifth pulse will
vary in amplitude
(8) Set CHAL ISLS SPACING SELECT switch to -.60 and CHAL MODE
SELECT switch to 1. Using technique of (3) above, measure pulse spacing from leading
edge of first pulse to leading edge of second pulse. If pulse spacing is not between 1.35 and
1.45 μs, perform b (4) below.
(9) Position controls as listed in table 8. Pulse spacing as indicated on oscilloscope
will be within limits specified in table 8, if not, perform appropriate adjustments.
