The Wayne Kerr 6565-30 10A DC Bias Unit, 20 Hz to 30 MHz, is designed for use with the 6500B Precision Impedance Analyzer or the 6500P HF LCR Meter (both sold separately). Its function is to provide a source of DC bias current through the Device Under Test (DUT) while the analyzer is making AC measurements. The 6565-30 unit can provide up to 10A of DC current, and up to eight 6565 units can be connected in parallel to supply a maximum 80A (additional units sold separately).

The digital ammeter on the front panel of the unit allows the user to see the DC bias current value, while an indicator LED shows when the bias current is enabled.

The high current 50Ω coaxial cable is used to carry the DC bias current from the 6565-30 unit to the fixture. The measurement signal from the 6500 analyzer front panel is connected to the fixture using a dedicated cable (sold separately), while a control cable connects the rear panels of the 6500 and 6565, and a safety interlock cable (sold separately) is connected from the fixture to the rear panel of the 6565.

Any 6500 analyzer can be used with the 6565-30 DC Bias Unit. The maximum measurement frequency of the system will be determined by the instrument with the lower maximum frequency. For example, a 120 MHz 65120P used with the 30 MHz 6565-30 will have a maximum measurement frequency of 30 MHz.

The 6500 analyzer controls the 6565-30 unit. The DC bias current is set as part of the 6500's measurement setup and the 6565's status and warning messages are shown on the 6500's display.

A common measurement of wound components with the 6500B/6565 system is to measure the value of inductance as the DC Bias Current through the DUT is swept from 0A to the DUT's rated maximum current.

Another common technique is to use the Reference Trace function on the 6500B Precision Component Analyzer. This allows frequencies sweeps performed at different DC bias current levels to be instantly displayed and compared on the 6500B's display.