Lime SDR XTRX external clock source HW layout

Projects LimeSDR
1

Hi,

I have been looking at the LimeSDR XTRX HW schematic for external clock feed on X7 U.FL connector, and I’m confused as to how is this separated from LMK00105’s CLKOUT3 signal which goes right back to X7 U.FL through R156 resistor.

So it seems as long as R156 resistor is populated on the board, as soon as I plug in external clock on X7 U.FL, do the right selection on IC15 using EXT_CLK signal from FPGA, LMK00105 will start to feedback the same signal (only delayed) back to X7 U.FL, and then inevitably back to itself?

Am I supposed to de-solder R156 if I want to use external clock signal then so that it is not messed up by LMK00105’s output?

Or maybe I have missed something?

Thank you in advance for any hint!

2

I’ve checked the actual board and R156 is not populated, so that is solved.