[time-nuts] Important RTFG interface information

John Ackermann N8UR jra at febo.com
Tue Feb 27 17:27:55 EST 2007

I just acquired the mysterious interface cable that goes between the
RTFG-m-XO and RTFG-m-RB units.  I have suspected that it wasn't a simple
crossover cable, because the results I've seen with my homemade
crossover haven't made a lot of sense.

Here's the scoop:  the interface cable is a simple DB-9 to DB-9 ribbon
cable with the ribbon flipped -- the striped side goes to pin 1 on the
RB end, and to pin 5 on the XO end.  We pretty much knew that.

However, the conductor on the other edge of the ribbon (between pin 5 on
the RB end, and pin 1 on the XO end) is BROKEN in the middle.

So, there is NO CONNECTION between XO pin 1 and RB pin 5.  (It goes
without saying, but I'll say it anyway, that this means the cable ends
are not interchangeable -- there is an XO end and an RB end.)

Hope this is helpful.  I got a few more interesting bits and pieces
along with this cable, but I think this is the important news for those
of us trying to interface these units at home.


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