A computer implemented system for testing electronic equipment where a plurality of types of systems can be tested using a single test specification. This is done by dividing the basic spot beam that has 3 to 4 dB of gain drop within the beam into a number of smaller 1-dB sub-beams. The surface of the cathode facing the alcohol-alkaline mixture is coated with a layer of a polymer, for example polybenzimidazole, having conduction in respect to OH\u2014 ions.