The PCD 121 is used for coupling of 1,2/50us – 8/20us combination wave impulses up to 6.6kV peak onto unshielded symmetrical data and signal lines according IEC/EN standards. Up to 2 pairs / 4 wires can be tested simultaneously. To obtain maximum flexibility only coupling elements are included in the PCD 121. Decoupling circuits, which depends on the EUT to be tested, can be placed separately in the test setup. Manual coupling path switching for common mode (longitudinal, line to earth) as well as differential mode (transversal, line to line) testing. Default coupling elements are gas arrestors and breakdown avalanche diodes. The coupling elements can be selected easily. The direct coupling output allows the customer to use his own coupling elements.