I have a friend with an AH-3 who said that he had good results using a coax output. He simply connected the center conductor of the coax to the big insulator and the shield to ground. The AH-3 and AH-4 are similar, so it probably would work. I have an AH-4 in my truck feeding a whip antenna, but I use the AT-180 with coax output in my shack. 73 and good luck, Warren, WM2Z