Bar graph ranges, Testing the probe – NARDA 8718B User Manual

Page 24

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Chapter 4

Making a Measurement

Bar Graph Ranges

The Range key is used to control how the bar graph displays

information. The digital display is not affected and the meter

automatically displays a digital value over the probe’s entire

measurement range. There are four available settings: AUTO,

HIGH, MID, and LOW. The bar graph has 100 divisions.
You will probably find it convenient to use the AUTO setting

most of the time, but under a few conditions you may find one of

the three fixed ranges useful. The following table illustrates how

the range setting will affect the bar graph. For simplicity, a

probe with a full scale rating of 100 mW/cm

2

is used as an

example.
Range

Measurement Range

AUTO

As the field level increases the bar graph

automatically switches between three ranges:

0.01 to 1, 1 to 10, and 10 to 100.

HIGH

1 to 100

MID

0.1 to 10

LOW

0.01 to 1

If you exceed the upper limit of either the MID or LOW range, the

bar graph will be replaced with the message RANGE

OVERLOAD. The digital display will continue to show the

correct value. If you exceed the full scale measurement range of

the probe, the word "OVERLOAD" will appear

Testing the Probe

Your Model 8718B is equipped with two RF sources for testing

probes. Press Test Source and both sources will stay on for

approximately 20 seconds.
A contact on the right side of the unit is used for testing low

frequency probes and the low frequency section of

ultra-broadband probes. Most probes have three test points

around the head of the probe. Position the probe so that one of

the test points touches the contact on the meter. You should

The Range Key only

affects how the bar

graph displays infor-

mation.

N

ote

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