Tektronix a621 a622 current probes tektronix a621 the tektronix a621 is a 2000a ac current probe this industrial style clamp on probe has a bnc connector and can be used with a shrouded banana plug adaptor so it can be used on digital multimeters tekmeterreg and oscilloscopes the a621 can measure ac currents from 100ma to 2000a peak over a frequency range of 5hz to 50khz the probe provides a 1mv 10mv or 100mv output for each amp measuredapplications motor drives inverters power