I checked this morning and I am getting 67-86% on all PBS transponders, and they do fluctuate that much. I noted that 11736 V is coming in at 91-93% at the same time. I am using a similar set up but my dish is a 24 year old Cosmos with a Coolsat 5000 and a DSR920 connected to it. When I set mine up for KU, my concern was getting and maintaining digital lock on my 920 and I have that. To specifically answer your question, my signal on Montana PBS is good, and stable enough to view on my big dish, which I could not attain on my 76cm dish. By the way, this mornings levels are with a moderate cloud cover.