Ultra-precision Capacitance Bridge AH 2550A Andeen hagerling

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.
Removed Capabilities


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.