Black Box 1-800-316-7107 



G.703 Balun - 75–120 ohm, 2.048 Mbps, Female

G.703 modules to convert 75-ohm dual coax hardware to 120-ohm, twisted pair.


12 In Stock
1 Year Double Diamond™ Warranty (Standard)

*Required field

Product Features

  • Solve mismatches between coax and twisted-pair equipment.
  • Make 75-ohm (dual-coax) and 120-ohm (twisted-pair) network connections.
  • Convert bidirectionally between G.703 balanced and unbalanced interfaces.
  • Features transformer isolation for protection against ground loops.
  • Choose from models that support 2.048-Mbps or 8-Mbps speeds.
  • 2.048-Mbps models can be ordered with 1.6/5.6 dual-coax connectors.


Make bidirectional G.703 balanced and unbalanced conversions and protect against ground loops.

Use G.703 75–120 Adapters to connect your G.703 network to your shielded twisted-pair equipment.

These adapters address the open network provision (ONP) requirement that European post, telephone, and telegraph (PTT) authorities offer 120-ohm twisted-pair terminations to their customers.

Use the adapters to convert the balanced G.703 signals from your bridges and routers to unbalanced G.703 signals. So you can use your 75-ohm coax hardware and communicate with 100-ohm or 120-ohm twisted-pair equipment. The adapters convert signals bidirectionally, too.

Setup is super easy. Just plug in the adapters. If needed, you can configure the shield connection between the 75-ohm and twisted-pair interfaces.

The G.703 75–120 Adapters support E1 data rates to 2.048 Mbps. For sending TX and RX signals over STP cable, order the MT256A-F, which has 1.6/5.6 dual-coax connectors.

The G.703 75–120 High-Speed Adapters support data rates to 8 Mbps.

Tech Specs

Approvals CE
Connectors Interface A: 1.6/5.6 Coax Connectors; Interface B: 8-pin shielded RJ-48C
Dimensions 0.8"H x 1.7"W x 2.7"D (2 x 4.3 x 6.9 cm)
Interface A: G.703 unbalanced; B: G.703 balanced
Speed 2.048 Mbps maximum
Transformer Isolation Up to 500 volts AC/DC
This product works with:

* Technical specification weight is the unit weight. It is not the packaged shipping weight. For shipping weight, please contact Black Box customer service at 877-877-2269.



Double Diamond Warranty Diamond

Double Diamond™ Warranty (Standard)

Take the risk out of equipment purchases with the Double Diamond™ Warranty from Black Box Network Services.

The Double Diamond Warranty is our warranty that protects your Black Box® brand products* from accidental damage, including drops, water, and power surges.

The G.703 75–120 ohm Balun 2.048 Mbps, Female comes with a standard 1 Year Double Diamond™ Warranty (Standard) already included.

During the warranty period, Black Box Network Services will repair or replace your damaged equipment within one week of receipt at NO CHARGE!*

Plus, get an Extended Double Diamond Warranty.

You can also extend your warranty or protect a previously purchased Black Box® brand product** for an additional year—for only 10% of the purchase price! Or, extend your coverage for a full three years for only 20% of the purchase price!

Ordering an extended warranty is easy: When viewing a product in your shopping cart, just select the one or three years of additional coverage in the dropdown menu under “Warranty Options.” For details, contact Customer Service at 724-746-5500.

* Warranty subject to certain exclusions and limitations ** Certain products may not be eligible.

What’s more, we also have a 45-day return policy. Simply call Customer Service for a Return Authorization (RA) number, return your product in new condition and in the original package, and receive a full refund.