An upgrade to the transmitter protection system (TPS) is being designed as part of the scheduled expansion of the Alcator C-Mod Lower Hybrid Current Drive (LHCD) transmitter system from 12 to 16 klystrons. The upgrade design is being done as collaborative effort between Alcator C-Mod and Rockfield Research, Inc. as Phases 1 and II of a Small Business Innovative Research (SBIR) grant. A plan is in place to first implement the new design for the cart supporting 4 additional klystrons and then to upgrade the TPS for the existing three carts supporting the 12 existing klystrons. Some parts must be added before longer pulse operation. Experience in operating the existing LHCD system and a study of the klystron design have indicated a need for this upgrade to improve the protection to the klystrons, improve reliability and noise immunity, improve personnel safety and reduce the size of the system.