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Eliminating RFI on the audio output to monitor amplifier


I was experiencing RF leakage from the audio output jack on my Flex 6600M that was getting into my external audio monitor amplifier during transmit even into a dummy load. A simple and low cost fix for this is to install a pair of audio isolation transformers in the audio output to block RF from getting into the monitor amplifier input stage. The MPOW audio isolator contains two miniature audio transformers with low inter-winding capacitance and has excellent audio frequency response and low distortion when operated at less than -3dBm. It does and excellent job of blocking RFI and ground loop hum.

Available from Amazon and other online sellers.

73, Geoff-W8GNM



  • Ronald Panetta

    I second the recommendation. I use one on my shack NUC PC and it works well. I do get some noise from my 6400 on the speaker out since integrating all rigs into a mixer. Should try this on the 6400. In my case not RF as noise present whith all rigs in RX.


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