Bill is referring to the fact that the dish focus is critical at Ku freqs. If you are too close or far from the true focal point, then you have to adjust dish position to get anything- and you are getting a side lobe "reflection?" rather then the main beam, so it would seem that your f/d is the problem.
I'd get good enough with C, switch to Ku on the same bird, and adjust the f/d at the scalar ring/feedhorn location. My Corotor did not have the f/d scale, the newer ones do. So I always have had to tweek and hope for the best. And- it's really critical at Ku freqs. I heard 1/8" wrong looses 50% of power (3 db) at
c band- it would be someting like 1/16" at Ku (?!)
It would seem that quality numbers on digital would be easier to use than the signal strength on analog. Remember to take away the ladder when you are comparing.
My current thoughts are to try the old Bullseye feed and see how it works for C. The probe is broken for Ku, so I will have to try the LNBF and see if that works for Ku.
I'm trying this rather than adapt the Corotor with servo. If that fails, I'll put it back on and use the ebay special pansat 2500, which has skew output control, in combination with a
Vbox II.
Larry