My latest antenna project has been the construction of an End-Fed wire antenna. After looking over several existing models, I decided to build one from scratch. Based on comments from PA3WIT and others, I chose to use a unun transformer to match the wire. The best choice was the FT114-43 ferrite torroid, however, the inductance was inadequate with one torroid. I added the second, using a 4-turn trifilar winding with 18awg wire. You can see the protatype in the pictures below. Like most end few wires, it is necessary to use a tuner for maximum benefit. I am using the KX3 and it turns very well from 160m to 6m with an swr of less than 1.4:1 in the worst case.
The wire for the antenna is Flex-Weave FW14P cut to 44 feet and using a 33 foot RG-58U feed line.