My antennas are all above a metal cabin roof. I had big problems, spent $$$, and now it all worksgreat, even with 1500 W RTTY on 80M: http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf http://www.balundesigns.com/ This should not be a problem! 73 Bill KO7SS on Mt Lemmon, AZ