I have a 2 Antenna ST16 and the original H. I modded the H with the two external antenna's purchased from Carolina Dronz. I use the FPVLR 2.4 and 5.8ghz extenders. I flew today to 2,500 ft without any breakup of signal or loss of telemetry. I have gone to 4,000ft @ 350ft alt over water/marsh...