Abstract: A circuit and supplemental power source connection scheme for a telecommunications modem transmission link are described. The supplemental power source is connectable at any point along a telecommunications wire, including the terminals of repeaters and remote terminals. The combiner circuit includes a diode bridge for ensuring the proper connection of externally connected high voltage power to internal circuitry of the power combiner. The combiner also includes a line polarity matching circuit that automatically configures to signally connect internal positive and negative voltage signals to corresponding positive and negative external signal lines on a telecommunications modem transmission link.