The SDMX50SP is one of three 50 ohm, coaxial, 8:1 multiplexers that can be used in a TDR100-based system. It consists of a surge-protected multiplexer circuit board enclosed in a metal housing and a separate strain-relief bracket. Both the multiplexer housing and strain relief bracket have holes drilled at a 1” spacing. This allows the SDMX50SP to be mounted onto a wall or attached to the backplate of a user-supplied enclosure or Campbell Scientific enclosure (e.g., ENCTDR100, ENC12/14, ENC16/18).
|Multiplexer Housing Dimensions||24.9 x 12.2 x 4.6 cm (9.8 x 4.8 x 1.8 in.) with mounts|
|Strain Relief Bracket Dimensions||20.3 x 4.3 x 1.3 cm (8.0 x 1.7 x 0.5 in.)|
|Weight||590 g (1.3 lb)|
|Input Power||12 Vdc|
|Quiescent Current Drain||< 1 mA|
|Current Drain during Switching||~ 90 mA (All multiplexers of the same level switch simultaneously for less than 1 s.)|
Number of FAQs related to SDMX50SP: 6
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These three multiplexers all use the same relay board, but the housing differs. The multiplexers are described side-by-side on page 2 of this brochure.
The most popular model is the SDMX50SP, followed by the SDMX50.
In applications where TDR probes are used to measure soil water content, the maximum distance from the TDR probe back to the TDR100/TDR200 (even through one or more multiplexers) cannot exceed 15 m (50 ft) when using RG58 coaxial cable; the CS605-L, CS630-L, and CS640-L TDR probes have an RG58 cable. When using low-loss coaxial cable, the distance cannot exceed ≈25 m (80 ft); the CS610-L, CS635-L, and CS645-L TDR probes have a low-loss coaxial cable.
In slope stability and rock mass deformation applications, the maximum coaxial cable length should not exceed ≈1 mile (5,280 ft). The maximum combined length of all SDM cables in the system should not exceed ≈76 m (250 ft).