B&K Precision 4045B - Manual - Manual (Page 26)

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Excessive distortion or aberrations caused by
improper termination are less noticeable at lower
frequencies, especially with sine and triangle
waveforms. To ensure waveform integrity, follow
these precautions:
1. Use good quality 50 Ω coaxial cable and
connectors.
2. Make all connections tight and as short as
possible.
3. Use good quality attenuators if it is necessary to
reduce waveform amplitudes applied to sensitive
circuits.
4. Use termination or impedance-matching devices
to avoid reflections.
5. Ensure that attenuators and terminations have
adequate power handling capabilities.
If there is a DC voltage across the output load, use a
coupling capacitor in series with the load. The time
constant of the coupling capacitor and load must be
long enough to maintain pulse flatness.
Impedance Matching
If the waveform generator is driving a high
impedance, such as a 1 MΩ input impedance
(paralleled by a stated capacitance) of an
oscilloscope vertical input, connect the transmission
line to a 50 Ω attenuator, a 50 Ω termination and to
the oscilloscope input. The attenuator isolates the
input capacitance of the device and terminates the
waveform generator properly.