Abstract: Fastening mechanism for a transformer module and a signal generator for mounting at a signal tower.A bottom pan is provided having a multi-use holder, a receptacle for a transformer module, and a holding structure with a cable opening for a signal generator. The pan is mated with a cover forming a terminal space, a terminal block being arranged in this terminal space. The transformer module has catch hooks which are secured to corresponding catch noses in the receptacle. The transformer module comprises a transformer, a rectifier, and a lead. The applied multi-use holder comprises a U-shaped cable channel region communicating with a cable lead-through opening in the side wall of the bottom pan. A cable wind-up structure is provided in the terminal space. The cover is held to the pan by at least one catch nose and one catch tongue that are applied to the bottom pan and that engage into corresponding recesses in the cover.