No I had a 20 degree c-band only Astrotel Precision gold lnbf. It worked great.
I had a cheap chinese ku lnbf (one of those cheap mini bullet sized ones) for ku and it worked well too.
I have the conical feedorn scalar ring for offset c-band dishes that came with the astrotel lnbf.
The bsc-621 was quite a disappointment on ku band. The cheap little ku lnbf out performed it by a long shot.
I had a cheap chinese ku lnbf (one of those cheap mini bullet sized ones) for ku and it worked well too.
I have the conical feedorn scalar ring for offset c-band dishes that came with the astrotel lnbf.
The bsc-621 was quite a disappointment on ku band. The cheap little ku lnbf out performed it by a long shot.