9500B
Calibration Manual
82
Special Cal: 'Adjust FREQ'
This is really a calibration of the internal frequency source, to an external frequency
standard. The 9500B generates a stream of square timing markers (as in Time Markers
Function — refer to the
9500B Users Guide, Time Markers Function
section) at
100 MHz. This is applied to the external frequency standard, and the internal frequency
DAC factor is adjusted until the external counter registers 100 MHz.
When to Adjust
The 9500B Frequency Uncertainty (5 years) is specified at 100 MHz as: ±0.25 ppm.
In either case, it is normally unnecessary to adjust the frequency at less than 5 year
intervals.
Equipment Requirements
Digital counter for 0.25 ppm clock accuracy measurements.
Example: Hewlett Packard Model HP53131A with Option 012.
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