The purpose of this manual is to help you use your Electronic Calibration (ECal) module confidently and effectively. ECal is a precision, single-connection calibration technique which uses fully traceable and verifiable electronic standards. Each module has unique S-parameter data that is stored in the module's memory. During calibration, ECal uses this data to calculate the error terms for your network analyzer.This manual provides instructions for operating and maintaining your ECal module. Also included are mechanical specifications and replaceable parts available for each model.The 85091/2/3/4/6/8/9D series provide two-port calibration solutions with operating frequencies starting as low as DC and ending as high as 9 GHz. The N4690/1/2/3/4/6D series provide two-port calibration solutions with operating frequencies starting as low as DC and ending as high as 67 GHz. and N7550/1/2/3/4/5A/56A series provide two-port calibration solutions with operating frequencies starting as low as DC and ending as high as 26.5 GHz50 GHz. The N4431/2/3D/56A series provide four-port calibration solutions with operating frequencies starting as low as DC and ending as high as 26.5 GHz.