If you were fortunate enough to score one of the HackRF Jawbreaker SDR boards from Michael Ossmann, you may have noticed the board has an SMA antenna connector as well as a built-in PCB antenna (intended for operation near 900 MHz). Ossmann recommends that you disable the on-board PCB antenna if you intend to use the board with an external antenna.
In this short video, HackRF co-developer Jared Boone demonstrates how to carefully make the necessary mod to the board, which entails carefully removing R44 and cutting the underlying trace.