Agreed with one exception; in the K3 the "roofing" (I hate that term) filter also rejects the 2nd i-f image. Wes N7WS --- On Sun, 7/18/10, Joe Subich, W4TV <lists at subich.com> wrote: In either case the sole design function of the "roofing" filter is to protect the IF chain from strong out of band signals.