B. Operator Performance Checks
B.4.17 Vertical Accuracy Check (ohms)
1. Vertical accuracy is checked by comparing CT100B impedance measurements against a load
of known impedance. The supplied 50 ohm terminator is required.
2. Within the Main → Settings → Display submenu, select the Ohms Rho button until Ohms is
marked with asterisks. An ohms at cursor reading now appears on the right side of the screen.
3. Connect a 50 ohm terminator onto the front panel cable connector.
4. Move a cursor out to a length greater than 300 ns. Impedance may change a small amount
from point to point.
5. Average impedance amongst a number of points along the trace determines vertical accuracy.
Impedance at cursor should be between 45 and 55 ohms.
6. Vertical accuracy should be checked for Short, Medium, and Long cable lengths.
B.4.18 Horizontal Scale Check
1. From the Main menu, set Cable Len to Long.
2. Using the M-FUNC button and M-FUNCTION knob, set Vp to 1.000.
3. Turn the HORIZONTAL SCALE knob counterclockwise. Horizontal scale should increase
beyond 61 m/div or 200 ft./div.
4. Turn the HORIZONTAL SCALE knob clockwise. Horizontal scale should decrease below
0.01 m/div or 0.03 ft./div.
B.4.19 Horizontal Range Check
See the cursor readout range instructions in Section B.4. Horizontal range and cursor readout
range are always equal.
B.4.20 Horizontal Position Check
This test is passed implicitly when the Cursor Readout Range and Horizontal Range checks are
passed.
120 CT100B TDR Cable Analyzers Operator’s Manual
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