PlutoSDR RevB external clock rework¶

The PlutoSDR RevA + RevB don't yet have an input for an external reference clock. This is rather sad, as it makes the PlutoSDR unusable for pretty much any applications in the context of cellular technology, where clock accuracy requirements are very high.

Replacing XO on PlutoSDR RevB with U.FL socket¶

The PlutoSDR board needs some kind of connector to feed the clock signal to it. In order to do so, we remove the XO and place a U.FL socket.

Step-by-step pictures following below:

Original PlutoSDR RevB¶

XO removed using hot air¶

VCC pad removed¶

We need to remove the VCC pad of the XO as the U.FL overlaps it and might short-circuit

GND soldermask removed for U.FL¶

We need to remove some solder-mask above the top layer GND copper in order to have a GND pad for the left-hand side of the U.FL

U.FL socket soldered¶

We can now solder the U.FL socket. Center pin goes to the pad that used to be the XO output. The right two pads can both be used: The top right pad is GND, and the bottom right pad is not connected and is soldered only to improve mechanical aspects.