cha-250hd is the revised cha-250b. The top section of aluminum has been replaced with a solid whip for greater flexibility and less strain on the lower sections in high winds. A uniquely designed broadband vertical requiring No ground radials. This is extremely easy to assemble, requires no tuning or adjustments and vswr is under 1.6:1 continuously from 3.5 to 57 megahertz! It is not a 1/4 wave vertical, but an end-fed long wire type antenna with a matching transformer in a vertical position.