The barrel plug required for DC power on the LD-11 transceiver is NOT the more common 2.1mm x 5.5mm type. It has a thicker center pin and is actually the 2.5mm x 5.5mm type. I have ordered 3 such barrel plugs (with screw terminals) on eBay for $6.95 FREE SHIPPING. eBay item number is 161010001626. KB1BBY Scott