Plugged sound card mic into speaker #ubitx

Tom, wb6b


In my case I hooked the microphone input of the USB sound adaptor to the high side of the uBitx volume control. That way I don't need to readjust the volume control to get the level correct if I use the uBitx for something else between running WSPR/Digital modes, and I can listen to the digital signals if I wish.

The signal level from the high side of the volume control, at least with the USB sound adaptor I have, is a little on the high side, so optionally you could put a couple of resistors in a voltage divider to lower the signal level a bit.

Tom, wb6b


Hi Rob,

What voltage do you read on the other side of the capacitor?  IIRC, there's about 4-6VDC on the output of the lm386.  If so, then your 2V is not going to matter much I think.



Bryan Corkran, VK3KEZ

I’ve found these work well and very cheap been around for years , use it for Wspr
no drivers needed in windows..

Rob French (KC4UPR)

I've been using my ubitx with the speaker output connected directly to my USB sound card input.  The sound card supplies ~2V for an electret mic, but I figured I was fine since the ubitx output has the 47uF capacitor after the LM386... But I just realized, that is the wrong polarity for a DC bias applied from the USB sound card!  I haven't seen a pop, but am I slowly destroying that output capacitor?