I have had reports of a very faint echo on my transmitted SSB audio. What confuses me is that it is present at the 100 watt level but goes away when I put my Ameritron ALS-600 on line. Hence, it does not appear to be RF in the audio related.
Running a Flex 6300 and SSDR 1.3.84. Also using the Flex-supplied Heil balanced to Foster connector cable. Mic is a PR 781. The radio is connected to my I7 computer running Windows 8.1 via a D-Link gigabit router. I have 31 mix torroids on the mic cable, speaker cables (sharing Bose Companion IIs with my Flex 5000), power supply in/out cables, etc. The antenna (GAP Voyager IV) is at least 100 feet from the house.