I'm not sure if this may have been asked before but has anyone had any problems with the range of their 2.4Ghz equipment through the use of a 5.8Ghz video transmitter? I was out over the weekend and noticed my plane seemed to have lost it's signal sooner than I would have expected when flying out. If it wasn't for my spotter I may not have got it back so thought it easier to ask the question than try again. The video signal never dropped out.
I was using and Spektrum Dx7 (no mods) with a 200mw 5.8Ghz Video tx. The Spektrum is at the front of the plane and the video tx is near the tail.
I used to have my Rx in the front of my FPV plane and would experience poor RSSI flying away from myself (I have FRSky telemetry, so I always managed to turn back before getting to the point of losing control.) I recently moved my Rx to the tail and haven't had much orientation-dependent range since. The antennas have good visibility from just about every direction back there.
I too have a 200mW 5.8GHz Tx, which I relocated to the center top of my wings. It has great visibility up there as well. So far I've flown ~1km with clear video.
It is also possible that something out there was causing interference on 2.4GHz. I've seen this a few times flying behind my local high school. I'd be flying with RSSI in the 60s and 70s, then suddenly dropping to the 40s in a specific area over the football field. They have wireless scoreboards, so that my be what was causing the interference for me. Also may be multi-pathing from the metal bleachers.
Try doing a 360° range test. You might find that you have great range from the front, but decreased range walking behind the model.
Hope something in there helps!