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The potentiometer, R1, is used to adjust the sensitivity of the meter from the front panel of the
instrument. J1 is a video jack and is provided for observing video waveforms with a test oscilloscope.
SUMMARY
The following is a brief summary of the important points of this chapter.
All IMPEDANCE BRIDGES have several things in common. Each type of bridge has a comparing
circuit and a measuring circuit. They measure an unknown impedance by comparing the characteristics of
the device under test with the characteristics of components within the test set.
POWER METERS that are designed to measure af power can be separated into two distinct groups.
Power meters that are designed for measuring sine waves are basically electronic voltmeters calibrated in
dB or dBm. VU METERS are designed to measure the average value of complex waveforms, such as a
voice.
The most common type of test equipment used to measure rf power is the ABSORPTION POWER
METER. Absorption power meters are designed to absorb all or part of the signal being measured.
Examples of absorption power meters are output power meters, in-line wattmeters, and meters employing
bolometers.
