The SDM8X50 is a new 50 ohm, coaxial, 8:1 multiplexer for TDR100-based systems that has replaced the SDMX50-series coaxial multiplexers. The main improvement over the SDMX50 series is hermetically-sealed, non-latching mechanical relays for both the ground and signal lines of each multiplexer channel and on the lines shared internally by multiple channels.
Benefits of these relays are:
- Quieter operation
- No oxidation buildup—Oxidation can cause erroneous TDR readings.
- Longer lasting—Specified for 100 x 106 operations, these relays provide 20 times more operations than provided by the SDMX50-series relays.
- Better surge protection—Relays unlatch 30 s after receiving a channel advance command so that electrical surges are less likely to have an electrical pathway back into the TDR100 and damage the TDR100’s input diodes.
The SDM8X50 consists of a surge-protected multiplexer circuit board enclosed in a metal housing and a separate strain-relief bracket for the coaxial cables. When purchased with the –N option, the SDM8X50 is a direct replacement to the SDMX50SP. When purchased with the –E option, the SDM8X50 comes in a 10-in.-by-12-in. enclosure similar to the now-retired SDMX50. To get a multiplexer that is equivalent to an SDMX50LP, purchase an SDM8X50-N and a standard ENC10/12 backplate (pn 6316).
