Texasbrit,
i do not have a SWM, right now that's the only thing I'm sure of. I am using 100ft of duel coax on a wind up spool. I tried reversing the duel coax to see if the trouble followed...it didn't. We had been using the receivers all week long, often being of different birds...no problems. When I got home, I tried to duplicate the problem on my slimline 5LNB, it didn't happen at home.
When I was at the campground, I was using about half of my coax, leaving about 50ft still on the reel. I'm wondering if the coil of the coax could be electrically causing the problem. I have been using this setup for the past seven years...the new thing is the dual coax on the reel.
The system works, but it sure has me scratching my head. It doesn't make any sense to me so I just can't leave it alone.