I thought about the voltage thing too. So I had my local, friendly Utility Company come out and put a Meter Recorder on my "Drop" and we measured the voltage on a couple of interior outlets with a fancy schmancy gizmo they had. It was Rock Solid 120.
My saga with the 811 actually involved the sound quality, and we (I) determined it's on their end. (I ended up keeping my original, and new 811. One of the "replacement" 811's sent to me had no DVI or Component Output!)
The 721 was a straight up replacement (in the same spot) for a much beloved (and waiting in the wings for a reinstall) 501. The 501 had great PQ, almost never lost signal in two years of use. All that changed was the addition of a Pro Quad LNB--Later replaced with a Legacy) and an extra feed. As I stated, Dish replaced every feed with new stuff. Even used the same S-Video cable. And my 811 works fine for OTA and HD--which is all that it is used for.
Right out of the box the 721, had intermittant feed on Tuner One, so we did the old "Cable swap" and still no feed. After a power off reboot and a "System Defaut" reset, I got Sat One, but I still lose it once or twice a Day.
PQ? On my TV, it was raining the last 10 Days of the Tour de France, even though it wasn't, Lance was this little shadow of Pixels in the distant shots, and he looked like a Leroy Neimann painting in the closeups.
The reason I'm asking about the guide is that the PQ is getting better. (No, I'm not getting used to it, I PVR'd the crummy stuff) Could this thing be "healing" itself? I didn't want to send the thing back if the flickering was considered "Dish Normal."