Re: Loud sound on first power-up #ubitx

Daniel Conklin
 

To state the obvious, it sounds like feedback.  Based on the harshness of it (square wave) I'd say it could be coming from one of the Raduino oscillators. However, you could get feedback if you have the PC board audio connector reversed, since that would cause the speaker output to feed into the mic input and the volume level to be reversed.  I'm just guessing of course, and you explained how you connected it in the video.  The wiring is pretty messy though, so it's possible that digital feedback is being picked up in another place incidentally.  It's also possible there is  bad capacitor or a short somewhere in the audio circuit. I hope that gives you somewhere to look that you haven't already thought of.  Eventually you will just need to trace the received signal from the input all the way to the audio amp section to find out where it fails.
73,
Dan, W2DLC

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