Lesson 1/Learning Event 7
(6) Digital distortion test set to measure distortion in DC telegraph
loops.
(7) Line test set to determine the condition of open-circuited lines.
b. Most-Often-Used Instruments.
Two types of instruments most often
used by the technical controller are shown in figure 1-26.
Figure 1-26.
Basic Types of Test Instruments
(1) Milliammeter. The zero-center-scale milliammeter is used to measure
milliamperes of DC telegraph loop current.
However, the technical
controller can use it for other purposes by interpretation of readings. He
can tell whether neutral signals
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