The SDM8X50 is the same as the SDMX50SP in form, fit, and function. When purchased with the –E enclosure option, a 10 x 12 in. environmental enclosure is included, making it functionally the same as the SDMX50. There is no comparable replacement for the SDMX50LP, which was the multiplexer and backplate used with the SDMX50 but sold separately for installation in a user-supplied enclosure.
The primary difference between the SDM8X50 and the SDMX50-series multiplexers is the electromechanical relays. The SDMX50-series products used latching relays with an expected lifespan of 5 x 106 operations. Because these relays were always latched, there was always an electrical pathway back to the TDR100 and an increased risk of damage from an electrical surge. The SDM8X50 uses non-latching, hermetically sealed relays with a lifespan of 100 x 106 operations. Additionally, relays have been added to the ground channels to electrically isolate them from each other and reduce interference. Thus, the SDM8X50 has improved surge protection, quieter operation, and a longer lifespan than the SDMX50-series multiplexers.