Ian, What definition of resonance are you using? I take it that you don't have a GDO built into computer? 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/ampfaq.html Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com Search: http://www.contesting.com/km9p/search.htm