This probably explains why I never experienced this. I never use the mic input with a URI as I like to send the pre-emphasized and limited audio directly to the modulator. This works quite well as long as you have a a transmitter using direct FM and not phase modulation. Steve WA6ZFT ******************************************************************** I find the term 'rxdemod=flat' a little confusing, since discriminator audio will contain pre-emphasized audio, generated by a user's transmitter. I assume that apt_rpt converts receive audio to 'flat' by de-emphasizing discriminator audio but not 'speaker' audio, (as selected) prior to presenting it to other nodes or to the transmitter software routines? I'm also guessing that the apt_rpt internal flat audio, generated as above or from other nodes/Iaxrpt, feeds the radio transmit software module, where it is treated as per the 'txprelim' switch before going to the analog interface. I hope I'm not the only one that wondered about the precise functioning of the usbradio.conf audio selections and how they operate. If I am, it's worth a beer. Snippet from usbradio.conf.sample: rxdemod=flat ; Rx Audio Source Type from Radio ; Options = no, flat, speaker ; no - RX audio input not used ; flat - source is un-filtered discriminator signal ; speaker - source is filtered, de-emphasized audio txprelim=yes ; Tx Audio PreEmphasis and Limiting in software ; no - Audio is not pre-emphasized and limited. ; for application to radio microphone input ; yes - Audio is pre-emphasized, limited and filtered ; for direct connection to an FM modulator I second Ken's motion to clarify the wording a little, next time you're revising the file. 73, Dave VE7MQ.