
load combination,
ringing
may still occur when tuning the scanner. This is especially true
for high Q scanner torsional resonances. The viscous damping coefficient increases as the
scanner
RMS
current (acceleration) increases, shifting the resonant frequency downward
slightly with higher tuning
speeds.
This tends to de-stabilize the system when a fixed
frequency, high Q notch filter is used. Lower
Q
notch filters can counteract this.
e) Adjust the Frequency pot on the NFM until a minimum is obtained in the NFM output
waveform.
f) Now adjust the Depth pot on the NFM to further minimize the output waveform.
g) Repeat steps (e) and (f) until the NFM output waveform at Fr is minimized as much as
possible. At this point, you are done.
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