[DannyP]

This may be a stupid question. But it is one that I've searched for and not found a real answer to. So I'll ask here rather than bother Weaver.

The little removable jumper at the edge of the board right next to the 22 pin connector.

Do we leave it installed or removed? When and why?

My UA4C is installed, working, and I use a Bluetooth interface to my laptop.

[PSIG]

That's the reset protection jumper. Leave the shunt installed on the jumper pins — except when you want to upgrade firmware. It enables a strong pullup to the Mega's Reset pin, preventing software grounding of the Reset pin, helping to avoid 'restarts' for a variety of reasons. Of course, in order to perform automated upload of firmware by USB or Bluetooth it will need a reset, so remove it for that.

[DannyP]

Thank you, David.

Clear, concise, and direct. Cheers!