I have a nice 352 Inrad (same as current 762 Inrad) 9 mhz IF 600 cycle filter for the Corsair II, Omni V/VI/VI+ or can be used in the original Orion as a roofing filter. On the Orion, works best if you put it in the 1k slot, instead of the 500 cycle slot. Will ship USPS 1st class for $55. 73, Don, WB5HAK