[amsat-bb] L/S helix feed

[w7lrd@comcast.net]

Hello
Questions on my current L/S helix feed.
I am building a dual L/S concentric helix feed for a 48x54 inch primestar dish.  The reflector is cut for  L band does that cause a problem with S band?  Where can I find a good design for a notch filter for S band to reduce desense?  Where does the focal point want to be on the helicies?  Or is it pretty forgiving.  Any other information is appreciated.
73 Bob W7LRD
Seattle