MANUAL TEST FUNCTIONS
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In the next example below, there is an electret microphone that is placed on an unbalanced
pair combination of 1:3. You can see a strong 2
nd
harmonic response on many pair
combinations that contain 1 or 3, and also some response on the unbalanced 2:6 pair whose
conductors are balanced with 1 and 3. This is an excellent example of inductive coupling that
can occur in a telephone line.
By further reducing the transmit power, it is easy to see that the pair that is tapped is 1:3.
From studying these types of responses it is easy to quickly identify different types of taps.
