Re: uBITX + Teensy audio interface - ground loops (?), RX/TX audio bleed? #ubitx #teensy

Rob French (KC4UPR)
 

Evan, thanks for the input.

Regarding the feedback into the headphones... that totally makes sense.  I will try the dummy load test.  My breadboard is a bit of a spider's nest, and even has a couple of wires floating in space at the moment (the mic input to the Teensy, which I don't actually have hooked up yet, since I'm using USB audio for my transmit audio).  I also noticed that moving my hand in various places around the system seems to impact the sound of the feedback audio--muffle it, change the tone a little, change the amount of hum, etc. 

I'm using a laptop computer.

I don't understand how I'd be missing a connection to ground, however.  USB carries a connection to ground, so the Teensy (and the Teensy side of the audio transformers) should be referenced to the same ground as the computer, via the USB cable, right?

I wonder if I should try switching USB ports?

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