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So, I had my uBITX powered only by the USB cable and was listening, turned it down (but not off).
Sometime later I had transmitted on another radio and heard either a click or a pop from my uBITX.
Now anything below about an s7 the uBITX can't hear when connected to 12v (it's completely deaf when only connected via USB now)
Any suggestions as where to start troubleshooting?
TX is fine.

Thanks?
Tom?

Hi Tom,

First, it is not a good idea to power the uBitx through the USB connector on the back of the radio.? That would be back-feeding the power through the 5-volt regulator on the Raduino board.? That can damage the regulator and ultimately cause it to fail and apply the full 12 volts to the Nano.

From what you have described, I would suspect that the power from the nearby transmitter damaged Q90.? Check to see if you have a short to ground on the base of Q90.? The alternative is to test following the directions on this spreadsheet from VU2ZAP:
/g/BITX20/files/VU2ZAP

The V6 and V4 have similar circuits for the transmitter, so the V4 measurements are good.

73
Evan
AC9TU

Hello Tom,
1) If arduino nano is running on 12V, but not via usb (and if usb connection is OK.) -? seems like something happened to arduino nano (power circuit?? MS1117? diodes?). Do You have USB power measure tool like Keweisi? So, You could measure (if any) current consumption by arduino nano via USB. Anyway, if nano is NOK it is not expensive to buy, reflash and replace.
2) Low RX might also be caused by Q10 transistor failure (and next ones Q11, Q12.. in RX chain). Please check voltages on them.

Regards
Tomasz

Thank you both for the great info!?

once things slow back down again, I’ll get to work on figuring it out