TB 9-4931-504-40
20. Delta t Center
a. Performance Check
(1) Connect pulse generator to CH1 and CH2 inputs, using cable supplied with
pulse generator.
(2) Position controls as listed in (a) through (c) below:
(a) CH1 and CH2 pushbuttons pressed.
(b) DELAYED SWEEP SEC/DIV switch to 1 ns.
(c) TRIGGERING LEVEL control for stable display.
(3) Superimpose two displays on oscilloscope, using CH1 and CH2 DC OFFSET controls.
(4) Adjust CH1 TIME DIFF CH2 control fully cw and then fully ccw. If one display
does not lead the other by 1 ns or more, perform b below.
(5) Press ADD and CH2 INVERT pushbuttons and adjust CH1 TIME DIFF CH2
control for minimum amplitude.
b. Adjustments. Adjust R458 (fig. 1) in conjunction with CH1 TIME DIFF CH2
control until either adjustment has equal control over leading edge or lagging edges of display.
21. Balance and Loop Gain
a. Performance Check
(1) Connect pulse generator to CH1 and CH2 INPUTS, using cable supplied with
pulse generator.
(2) Release ADD, CH2, and CH2 INVERT pushbuttons.
(3) Press SWP pushbutton and set DELAYED SWEEP SEC/DIV and DELAYING
SWEEP switches to 2 S. If dot displayed on leading edge is not within one-half division of
top display, perform b (l) through (7) below.
(4) Press CH2 pushbutton. If dot displayed on leading edge is not within one-half
division of top display, perform b (8) through (12) below.
b. Adjustments
(1) Remove connection from CH1 and set both DELAYED SWEEP SEC/DIV and
DELAYING SWEEP switches to 1 S and press HF SYNC pushbutton.
(2) Adjust R233 (fig. 2) for no vertical movement while simultaneously adjusting
R232 (fig. 2) back and forth between fully ccw and 90 degree position. Readjust R232 fully ccw.
(3) Set CH1 VOLTS/DIV switch to 10 mV. Center trace on horizontal graticule
with DC OFFSET control.
(4) Press LO NOISE pushbutton and adjust R242 (fig. 2) for no trace shift while
pressing and releasing NO NOISE button.
(5) Release LO NOISE and HF SYNC pushbuttons. Set CH1 VOLTS/DIV switch
to 50 mV and DELAYED SWEEP SEC/DIV and DELAYING SWEEP switches to 2 S.
(6) Reconnect pulse generator to CH1 and release HF SYNC pushbutton.
