TB 9-4931-538-40
Figure 20. Top adjustment.
y. Press Channels key and set CHANNEL 1 OFFSET to Offset = 0.000V.
z. Press Timebase key and set TIME/DIV to Sweep Speed = 50.0 ps/div, DELAY to
Delay = 16.0000 ns.
aa. Press Timebase key and set Sweep Speed = 50 ps/div and Delay to 16 ns.
ab. Press Delta V key and ensure that the MARKER1 position is highlighted.
ac. Adjust BOTTOM on horizontal assembly Al (fig. 11) until the trace coincides with
MARKER1 position.
ad. Press Channels key and set CHANNEL 1 OFFSET to Offset = 200.0 mV.
ae. Press Timebase key and set DELAY to Delay = value of the START MARKER.
af. Press Timebase key and set Delay = value of the START MARKER.
ag. Press Delta V key. Change the value of MARKER1 to equal the value obtained in
step f above. Press MARKER2 key until that cursor is highlighted. Adjust the RPG
control for a Delta V reading of between 5 and 7 mV (this will correspond to an overshoot of
about 2.5 to 3.5 percent).
ah. Slowly adjust the TDR DRIVE on horizontal assembly Al (fig. 11) until the peak of
the overshoot coincides with the MARKER2 position (fig. 21). If the overshoot moves off
the display, reposition the waveform with Delay. If this adjustment fails, repeat the TOP
and BOTTOM (fig. 11) adjustments.
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