I was also wondering if anyone has the pinouts to connect an X72 to a SyncServer S200 (or S250, S300, S350 etc), basically adding the Rb option? I've gotten it much of the way there, but it doesn't *quite* seem to work reliably - from looking carefully at the sales brochure (https://www.microsemi.com/document-portal/doc_download/133299-syncserver-s200-datasheet, P3) it *seems* to just be a cable from an "X72 circuit card adapter" (P/N 106568-002) to the header (and removing a jumper to use the external oscillator). It will happily show the Rubidium oscillator option (http://photos.kumari.net/Projects/AtomicClocks/i-bTBhk7z/A), but doesn't seem to lock reliably -- originally I was suspecting that it was that the Rb wasn't being controlled, and that I needed to feed pin 11 (FREQ CNTL - Frequency control), but this doesn't seem to help. There are a surplus of X72s (and similar, see Mark's SA22.c -> X72 connector board!) around, and many of the Symmetricoms were purchased without the Rb option, so this seems like an obvious thing to do. W -- I don't think the execution is relevant when it was obviously a bad idea in the first place. This is like putting rabid weasels in your pants, and later expressing regret at having chosen those particular rabid weasels and that pair of pants. ---maf