The TIS-B1 Balun converts a 50 Ohm signal to a balanced 100 Ohm impedance as needed when using twisted-pair CAT 5 and CAT 6 ethernet cable.

While this was designed with balanced receive antenna systems in mind, the Balun has also proven very useful in scientific and industrial applications for distribution of clocks and data with a minimum of common-mode interference (both ingress and egress).  The Balun has also been successfully used in the testing of custom twisted-pair cables, allowing interface to standard 50 Ohm test equipment.

The TIS-B1 Balun is sold individually.  You may want to buy two!