Standalone Universal HDSL Unit

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  • HDSL Classic (2B1Q), HDSL 2, dual HDSL 2, and HDSL 4 with support of -129 Vdc & -190 Vdc on the loop
  • Data transmission lines within the passband of the card
  • Provides Station side Span Power that is used to power-up a repeater (H4R) at -129 Vdc at 20 ma, or -190 Vdc at 20ma. Note that there is a 2,000 ft reduction in total distance with each additional SP card installed within the span.


The Standalone Universal HDSL units provide high voltage isolation between one, 4-wire Remote Terminal Unit (HTU-R) located inside the substation, and an HDSL Central Office (CO) Terminal Unit (HTU-C) located at the CO.

These units consist of an isolator card mounted inside a compact enclosure. The enclosure is molded from fiberglass, making it a lightweight, flame-retardant container of high dielectric strength. Its fiberglass body limits the possibility of many kinds of infiltration while providing reliable isolation from external ground potentials.

Each standalone unit is shipped with a 10’ insulated 12-conductor cable for connection to the CO’s incoming cable, and mounting hardware.


  • Units provide isolation 50 kVrms (70 kV peak) while maintaining full communication between terminals
  • Communication is maintained across the gap by isolation transformers that provide low-loss, low-distortion transmission
  • Model 751239SP requires -129 Vdc or -190 Vdc on the Station side to provide span-power
  • Enclosures resist the infiltration of dust, mist, and water from sprinklers
  • Jumper settings allow you to configure cards to provide a simplex sealing or a loop sealing return path on the CO side. The current will not be transferred to the Station side. Cards are shipped with these options disabled