A reduced size multiplexer and, in particular, a reduced size SONET multiplexer module is provided for use in a reduced size enclosure. The SONET multiplexer module has electrical and optical connectors on its faceplate to provide ease in access without having to remove the SONET multiplexer from the enclosure. The SONET multiplexer circuit is configured in a standard Type 400 mechanics circuit board arrangement. The SONET multiplexer module therefore can be inserted into an enclosure in a direction opposite to that in which the coaxial connector projects from the face plate, so that the coaxial connector remains freely accessible outside of the enclosure when the SONET multiplexer module is fully loaded into the enclosure. Coaxial cables and optical fibers can thus be easily coupled to the coaxial and optical connectors, respectively, when the SONET multiplexer circuit is fully loaded into the enclosure.