Tektronix 1502C Using Vertical Set Reference, Vertical Compensation for Higher Impedance Cable

Operating Instructions
1–26 1502C MTDR User Manual
VERT SET REF works similar to HORZ SET REF except that it sets a reference
for gain (pulse height) instead of distance. This feature allows zeroing the dB
scale at whatever pulse height is desired.
1. Turn NOISE FILTER fully counterclockwise. “Set Ref” will appear in the
noise averaging area of the LCD.
2. Adjust the incident pulse to the desired height (e.g., four divisions). It might
be necessary to adjust n
oPOSITION.
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set vertical scale and press STORE
Figure 1–26: Incident Pulse at Three Divisions
3. Push STORE.
4. Return NOISE FILTER to the desired setting. Notice that the vertical scale
now reads 500 mr/div.
NOTE. The millirho vertical scale will not be in calibration after arbitrarily
adjusting the pulse height.
The millirho scale is the reciprocal of the number of divisions high the pulse has
been set. For example, 1 pulse divided by 3 divisions equals 0.25 mr equals
250 mr/div.
When testing cables other than 50W, this procedure allows reflection measure-
ments in millirho.
1. Attach a short sample of the given cable (75 W in this example) to the
instrument.
Using Vertical Set
Reference
Vertical Compensation for
Higher Impedance Cable