Roofing Filter for TS-850 ? Yes it's possible ! even without VNA http://pagesperso-orange.fr/F6AOJ/cariboost1/crbst_178.html This page is now updated, you will read how to tune circuits without VNA. 73 Jeff F6AOJ http://pagesperso-orange.fr/F6AOJ/cariboost1/crbst_0.html