ScottV,
Not an expert on these joiners, this my understanding, from reading forum previous posts, they take a separate 12 volt DC power supply similar to a DB9s power supply, that plugs into the joiner. Following is from forum post “
As Tracker John states a regulated 12VDC power supply is required for the joiners to work as an amplifier. That is provided by the barrel jack connector that plugs in at the top.” AmFlyer thank for post below, see more detailed information in post below by AmFlyer.
Les