Ok, I think I figured out my Q drops and I'll recommend all powerbox users that get telemetry from their PB do a simple test,

BLUF: If my powerbox telemetry is plugged into a RX, at perfectly repeatable intervals my signal quality goes to hell. In my original config, RX 2 would start flipping all over the place at about 11 min and powerbox power on, and RX1 at about 14 min. My Q got as low as 8% sitting in the same room at my model.

DISCUSSION: Tried several receivers, no luck. If I unplug the PB tememtry lead, signal Q is rock solid forever. Using dual path, 10ms, direct, FS off, UDI.

This is pretty disturbing. Suggest others check this out. Suspect there are multiple processors at play and clocks get slightly but predictably out of synch resulting in the perfectly repeatable intervals.

Let me know what you find!

https://youtu.be/mE6vS3a6q7E