HP 54540 Series - Page 73

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Chapter 4: Calibrating and Adjusting
To adjust the high-frequency pulse response
If the pulse edge is not on screen, adjust the delay to set it near center screen.
Press the channel number key and adjust the position to place the flat part of the
pulse top over the grid line, one division from the top of the display.
Adjust the resistor to extend the peak over the grid line, so that the overshoot is
about 3%, a little less than one vertical minor division, as shown in the illustration.
(One vertical minor division is about 4% of a six division signal.)
54510WO1
When the resistor is adjusted, the gain changes. It may be necessary to use the position to
reposition the pulse top to the grid line.
There is no specification for pulse response. However, if overshoot is more than about 3%
(about 3/4 minor division), use the resistor to reduce it slightly. If the instrument fails the
bandwidth test, use the resistor to increase overshoot slightly.
If necessary, repeat steps 1 through 8 on any other channels needing adjustment.
Perform the bandwidth test (Performance Tests) on any channels that have been
adjusted.
If you have readjusted the pulse response, the channel gain has changed. You must.
recalibrate the channel (self cal) as given in the next procedure, "To claibrate the
firmware."
Reassemble the instrument.
Instrument warm-up
Before the Firmware Calibration, the next procedure that is part of a routine calibration, you will
need to let the instrument warm up for half an hour with the cover installed.
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