Tektronix TSG 90 PATHFINDER, Service Manual

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Performance Verification and Adjustment Procedures
TSG 90 PATHFINDER Service Manual
3–12
a. Select the Multiburst signal from the PATHFINDER (press C).
b. Set the 1780 to view all of the multiburst packets on a line.
c. ADJUST — L4, L5, L6, L7, and L8 to make the frequency packets flat,
and equal amplitude from one packet to another. Use the 1780 WFM +
CAL function to confirm that all packets are of equal amplitude
±
1.5%.
d. Select the NTC7 Composite signal from the PATHFINDER (press D).
e. Set the 1780 to view the bottom of the modulated and 2T pulses.
Magnify as necessary to view the ringing.
f. ADJUST — L7 and L8 for symmetrical ringing. Use the 1780 K-Factor
graticule to verify that the ringing (overshoot) is
≤
0.5% of peak.
g. ADJUST — SIN X/X Correction, C6, to make the bottom of the
Modulated Pulse as flat as possible.
h. Return to part a and repeat this step. Continue to repeat this step until the
best overall response is obtained.
6. Adjust LCD Contrast
a. Press the BARS button, to make sure that the LCD backlight is on.
b. ADJUST — LCD Contrast, R1, counterclockwise until the unused LCD
segment rectangles appear, then adjust R1 clockwise until they just
disappear. Stop adjusting R1 before the intensity of the displayed LCD
characters is affected.