The World’s Most Accurate Capacitance/Loss Bridge The AH 2550A offers unparalleled stability, resolution and accuracy in a capacitance/loss bridge (whether manual or automatic). Its numerous state of the art features make it an exceptionally user-friendly instrument, just as was its predecessor, the AH2500A. The precision and ease of use of the AH2550A are creating new applications in science, calibration, and production in a wide range of fields. The AH2550A has replaced the non-option-E version of the AH2500A. The latter product is no longer available. The AH2550A is designed to be an improved substitute for the AH2500A and should be capable of replacing the AH2500A in virtually all applications. A summary of the differences between these two products is given in two lists below. The first list contains enhancements to the AH2550A that are not present in the AH2500A. The second list contains capabilities present in the AH2500A that have been removed from the AH2550A. Added Capabilities:

Patented, digital phase-shifting circuitry needs no calibration and is temperature independent.

Enhanced test diagnostics are better able to isolate component failures and require less intervention by the operator.

Line-related noise rejection has been made even better.

Complete re-design of the digital circuitry provides very high reliability.

Upper limit of test signal voltage has a minimum setting of 0.3 mV versus 0.5 mV previously.

Largest measurable capacitance is now 1.5 µF versus 1.2 µF previously.

A real-time clock has been added.

The serial interface is compatible with the IEEE-1174 Standard.

The front panel display is fully alphanumeric.

The number of LED indicators on the front panel has been increased from 8 to 10. Options:

Deviation Mode allows measuring small, fast changes relative to fixed capacitance/loss settings.

Deviation Mode results can be sent to fast analog voltage outputs for both capacitance and loss. bRemoved Capabilities/b

Option-E is not currently available. It can be purchased with the AH2500A while parts last.

There is no serial 20 mA current interface.

The resolution specification has changed from 0.5 to 0.8 aF. The actual performance has not changed.