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Overview
The SDM8X50 is a 50 ohm, coaxial, 8:1 multiplexer used in a Campbell Scientific time-domain reflectometer system. It consists of a surge-protected multiplexer circuit board enclosed in a metal housing and a separate strain-relief bracket for the coaxial cables. Both the multiplexer housing and strain relief bracket have holes drilled at a 1 in. spacing. This enables you to mount the SDM8X50 to a wall or attach it to the backplate of a user-supplied enclosure or Campbell Scientific enclosure.
When you purchase the SDM8X50 with the –E option, a 10 x 12 x 4.5 in. environmental enclosure and enclosure supply kit are included. Other compatible Campbell Scientific enclosures that you may purchase separately include the ENCTDR100, ENC12/14, ENC14/16, and ENC16/18.
Benefits and Features
- Longer lasting relays; 20 times more operations than SDMX50 relays
- Non-latching relays provide better surge protection
- Hermetically sealed relays are more stable and do not become coated with a non-conducting film
- Quiet operation
3D/CAD Files:
Specifications
| Operating Temperature Range | -40° to +55°C |
| 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.) |
| Multiplexer Weight | 590 g (1.3 lb) |
Power Requirements |
|
| 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.) |
| Relay Contact Life Expectancy | 100 x 106 operations (at 5 V and 10 mA) |
Enclosure (-E option) |
|
| Outside Dimensions | 40.4 x 29.2 x 17.5 cm 15.9 x 11.5 x 6.9 in.) with mounts |
| Inside Dimensions | 25.4 x 30.4 x 11.4 cm (10 x 12 x 4.5 in.) |
| Weight | 4.1 kg (9.0 lb) |
Compatibility
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
Dataloggers
| Product | Compatible | Note |
|---|---|---|
| 21X (retired) | Although compatible with the SDM8X50, this data logger is not compatible with the TDR100. | |
| CR10 (retired) | Although compatible with the SDM8X50, this data logger is not compatible with the TDR100. | |
| CR1000 (retired) | ||
| CR1000X | ||
| CR10X (retired) | ||
| CR23X (retired) | ||
| CR3000 (retired) | ||
| CR6 | ||
| CR800 (retired) | ||
| CR850 (retired) |
Additional Compatibility Information
Enclosure Considerations
When purchased with the –E option, a 10 x 12 x 4.5 in. environmental enclosure and enclosure supply kit are included with the SDM8X50.
Related Documents
Related FAQs
Number of FAQs related to SDM8X50: 1
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The PC-TDR software is compatible with the SDM8X50 multiplexer, but the non-latching relays may cause issues. When PC-TDR (version 2.08 and lower) advances to a multiplexer channel, it sends one command to the multiplexer. With the older SDMX50-series multiplexers, one command was sufficient because the relays latched. The non-latching relays on the SDM8X50 release 30 seconds after the command is sent, which results in a loss of connection between the sensor on that channel and the TDR100. To latch again for a good reading, it is necessary to manually force PC-TDR to go to a different SDM8X50 channel and then back to the channel of interest. The continuous waveform function should not be used with the SDM8X50. These known issues will be addressed in the next version of the PC-TDR software.