Abstract: A portable circuit tester for troubleshooting a multiplier circuit card of the AN/MPS-9 and the AN/MSQ-2 radar systems, particularly when these systems are van mounted. During normal operation of the circuit tester, the circuit card is completely removed from the equipment console and connected to the test box. The test box circuitry provides the power supply and control selections necessary to operate the circuit card under realistic conditions while also allowing easy access to all components on the circuit card. The output from the test box is fed into one channel of a dual channel oscilloscope, with the input for the other channel coming from a probe connected to the test points on the circuit card being examined.