Two more scans tonite. The antenna direction and elevation did not change from the scan in my previous post above.
One, I completely removed the attenuation, preamp & injector from the mix, and took my scan at the same TV location connected straight to the RG11:
Two, I kept the attenuation, preamp & injector removed, but replaced the surge protector with a grounding block/coupling, scan completed at the TV:
The results were very close. The grounding block/coupling actually decreased the signal slightly. I'd say that's because my ground wasn't cleanly connected to the block... I noticed that after the scan.