The MG9001A/9002A can be used as stabilized light sources for different applications by changing the light source units. In particular, they have been designed for a high output stability of 0.02 dB. The MG9001A can hold 2 LED light source units. The MG9002A can hold 12 LED light source units making it ideal for measurement of loss in multi core fiber cables. Analog and digital modulation functions are also provided in both models, which means that they can be used as E/O converters.