TB 9-4931-538-40
n. Adjust the TDR DRIVE on horizontal assembly A1 (fig. 11) so that the pulse
overshoot is between 2.5 to 3.5 percent; use the Measure Menu to check this adjustment.
If the TDR DRIVE (fig. 11) adjustment moves the edge off the display, reposition the edge
with more Delay In the Timebase menu.
o. Press Delta V key and press Preset Levels key until 50-50% is highlighted. Press
Auto Level Set key.
p. Press Delta t key and press START ON EDGE key until POS 1 is highlighted.
Press the STOP ON EDGE key until POS 1 is highlighted, then press Precise Edge
Find key.
q. Press Channels key and set Channel 1 Off and back On. Set VOLTS/DIV to
Sensitivity = 2.000 mV and OFFSET to Offset = 0.000 V.
r. Press Delta V key and press Preset Level key until 50-50% is highlighted. Press
Auto Level Set key. If V(l) is greater than 0.5 mV, perform a channel vertical cal (see
Utility menu). Change the value of MARKER2 to 200 mV. Adjust the RPG control until
the Delta V equals the value recorded in step f above (marker resolution limits this to
within 0.06 mV at this sensitivity).
s. Press Network key and press Reflect/Trans/Cal key until Reflect is highlighted.
Press Step & Chan 1 key until On is highlighted.
t. Press the Delta t key and change the value of the STOP MARKER to the value of
the START MARKER +1 ns.
u. Press Channels key and set Channel 1 OFFSET to Offset to = 200 mV.
v. Press Timebase key and set TIME/DIV to Sweep Speed = 100 ns, DELAY to
Delay = value of START MARKER.
w. Press Delta V key and ensure that the MARKER2 position is highlighted.
x. Adjust TOP on horizontal assembly A1 (fig. 11) until the trace on the right of display
coincides with MARKER2 position (fig. 20).
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