The receiving antenna port designation on my Flex 6700 running version 188.8.131.52 hops around erratically. It inserts Loop A or Loop B resulting in no signal and sometimes strange noise and "phantom" signals every 10 to 20 KHz. This is especially bad on 20 meters. This only started happening with the latest software version. I'll see ANT 1 with Loop B for receive, something I've never intentionally set. I have to hop around to different antenna settings and eventually release the Loop B (sometimes it is Loop A) and then, mysteriously, I get the ANT 1 I'm seeking. So far I've not been able to establish a consistent pattern.