I haven't tried yet with a fixed Ku band dish, but on my C Band dish, about the lowest I can go is 45W, but the limitation is the actuator arm is in as far as I can make it go, so I stopped at 50W C Band.
And what's REALLY stupid about this (I hate to admit this) but I failed on two accounts, I was looking for 30W (not the 50W I found) and I was doing it with a C Band dish, not Ku Band.
Pretty stupid, eh?
Oh, this from 90 miles south of Las Vegas, 70 miles south of Hoover/Bolder dam.
But the really GOOD thing is, I now have a really great alignment on the entire arc from 50W to 139W, though I don't have an H2H motor, just a short actuator arm (so far).
Photto