"Harold Hallikainen" writes: > I'd put the transformer at the receive end of the line. Either end breaks > the ground loop, but putting it at the receive end also removes common > mode voltage. >=20 > Harold > W6IWI Thanks. Interestingly enough, that was what I had planned to do. EMI can be very sneaky and it sometimes seems to outwit every measure to stop it. It seemed to me that a short pigtail to the audio output on the radio would not pickup the racket like that 15 or 20-foot run of cable to the mixer amplifier. The hash is probably present on the transformer's frame but as long as it does not touch the chassis of the radio, the receiver should be quiet. If there is still any trouble, it may take a second transformer and short pigtail at the other end but I'll try the simplest approach first. One thing for sure. The hash adds about 10 DB of racket to the noise coming from the radio so I'll know I have it when it is about the same with or without the connection. Martin WB5AGZ --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .