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Visible Noise on DC Voltage Output Signal on the 5500A Calibrator

Text from Service Alert SA-1330

Model 5500A

S/N affected: All

Service Alert Date: 1-Aug-1996

Units affected: All 

Purpose: Visible Noise on DC Output Signal


Fluke Authorized Service Centers have noticed a noise problem on DC Outputs from the 5500A normal output terminals.  These spikes are particularly noticeable when programming a DC Voltage in the 33 Volt range of the calibrator and viewing the output with a digital storage oscilloscope.  These spikes are due to digital noise from the clock on the in-guard processor.

The noise, however, does not affect the utility of the output as a meter calibrator. This particular output is used only for meter and not for scope calibration.  The normal meter workload of the 5500A will not register these spikes. The frequency response of the input circuitry that is typical of these meters is not sufficiently broad to detect them. Any noise from these spikes is taken into account in the floor specs for the individual ranges.


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