Ground Considerations
Reliable signal measurements cannot be made unless both the
oscilloscope and the unit under test are connected together by a
common reference (ground) lead in addition to the signal lead or
probes. The ground straps on the attached probes provide the best
ground. Also, a ground lead can be connected to the-212 chassis
COMMON banana jack to establish a common ground with the
signal source.
Input Coupling
The INPUT COUPLING switches allow a choice of the coupling
method for the applied signals. The type of display desired and the
applied signal will determine the coupling method to use.
In the AC coupling position, the DC component of the signal is
blocked by a capacitor in the input circuit. The low-frequency
response in the AC position is about two hertz (-3 dB point).
Therefore, some low-frequency attenuation can be expected near
this frequency limit. Attenuation in the form of waveform tilt will also
appear in square waves which have low-frequency components.
The AC coupling position provides the best display of signals with a
DC component which is much larger than the AC component.
14
212 Operators Handbook
