Thanks for the responses Joe S and Joe L (like Supermans father, right?)
I've been printing cyanotypes using darkroom derived negatives (Bergger 18 ortho & pos/neg process) and the banding becomes apparent in the printing out stage. Moving the prints back 3/4 of an inch has helped alot with no discernable change in exposure and I'll be increasing the distance another inch or so next weekend.
Thanks Again