A friend of mine is using an AH-4 mounted on roof top mast. End fed antenna length is 84' and the ground wire from the AH-4 to a ground rod at the base of the mast is 32'. The AH-4 seems to tune OK on all bands except those frequencies below 3875 and 28500. Would appreciate comments from those who are familiar with the AH-4. Thanks, Joe k7mks