Run alsamixer in a terminal, hit F6 key, move down to the soundcard you want, hit Enter.? Hit F5 key to show all settings.? The "Speaker" slider is obvious, audio-out.? Use up/down arrows keys to increase/decrease.? The next slider, "Mic", should be muted or at zero; it's for playback thru speakers what it hears on the mic-in, so that's no good for digital modes.? The next slider, "Capture, Mic", is audio-in from the radio, make sure it isn't muted and has some level indicated.? The last slider,"Auto Gain Control" should be muted.? Muting is toggled on/ff using the "M" key.? If a slider is muted, you'll see two "MM"s.? When finished, hit Escape to exit alsamixer.? The settings are saved automatically if you're using a Raspberry.? In other Linux flavors, run "sudo alsactl store" in a terminal to save the alsamixer settings.
Jeff KP3FT