This should help: <http://info.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html> Watch the wrap. Phil Alexander, CSRE, AMD -----Original Message----- >From: Edwin Bukont <ebukont at msn.com> > >I know is has been posted here before, but can someone >please repeat the method to determine the value of the >large coils that we use in AM networks.