Can the E4980A/ 4284A measure DUT when "Warning, ALC unable to regulate" is displayed?
When "Warning, ALC unable to regulate" is displayed, DUT's impedance is outside the effective operating range of auto-level control (ALC) function. Though the test signal level cannot be controlled at the ALC setting value, the E4980A/ 4284A can measure DUT at the test signal level displayed in the VAC and IAC monitor fields. Even when the ALC function is ineffective, it does not directly affect measurement accuracy and stability.
Note: When DUT's impedance varies depending on test signal level, take into consideration the measurement discrepancy due to the difference in test signal level between the ALC and non-ALC operating status.