I myself have a Rig Expert AA-54 and always have it with me in the field. Easy to use and ideal for fine tuning the (field) antenna setup. Most of the time I working with a 10/20/40m endfed which depending on the environment it sometimes needs some tuning (folding back or unfolding the end). With the AA-54 you make a SWR band analysis (a little wider then the original band) and you know what to do.