Hi I have a XPR 6550 that I use for my fire department that operates in the 154 range. But I also want to use it for ham radio 144-148. Currently the antenna I have on it is "Combination VHF/GPS, 147 – 160 MHz, Helical Antenna3(PMAD4068_)" What I am wondering is this antenna ok to be using? I also have a XPR 6100 which I have the following antenna installed on it "VHF Wideband, 136 – 174 MHz, Double Helical Antenna6(PMAD4088_)" It works very well I talked to a friend on simplex who was 19 miles away with it. I am wondering if I should purchase another one of these for my 6550. I know it does not have the gps antenna built in but we do not use that anyways. What is the difference between a helical antenna and a "double" helical antenna? I determined what antenna was on my 6550 by using the color code chart.