John, Not using a balun (and never have with this antenna). There is a winding of eight turns of coax as an RF choke at the beam. It worked very well for many years in this configuration and has just now manifested the problem. Thanks. Bernie In a message dated 1/18/2007 6:13:17 P.M. Central Standard Time, n4dsp at triad.rr.com writes: Balun? john-n4dsp