Keithley 62212182ae digital multimeter dmm keithley 62212182ae the keithley 62212182ae is a digital multimeter complete with delta mode system nanovoltmeter and all necessary cables the 6221 combines ease of use with exceptionally low current noise it is ideal for applications in test environments ranging from rampd to production especially in the semiconductor nanotechnology and superconductor industries the 6221 is the only low current ac source on the market before its intro