On 05/17/2017 04:24 AM, Gene Heskett wrote: [snip] > The ideal situation in this instance would be to mirror the design of the > 7i90 so as to rotate the 26 pin header 180 degrees, which would allow > the cable to be only an inch long. Or mount the pi upside down, which > would have the same effect. Humm, why not, I have some looong > standoffs? While I'm waiting on 7i42TA's, why not try it? More than > one way to skin this scrawny cat.
Reducing the cable's length to an inch would help. Then the transmission line characteristics would be much less a problem at 50MHz. > Why is it I think best while writing > about a problem? Can't be the age of the wet ram. Or is it... :( It is called reflection of your own thoughts ;-) It works very well while doing something completely different (like taking some time on the toilet). >> BTW, I think that not only the probe tip has influence, but also where >> your probe's ground-lead is placed (and not that fluffy long >> aligator-clip lead). > Chuckle, guilty yur honor, but its only a 4" lead. :) In this case > clipped onto a corner of a usb sockets frame. Well, using the default ground-lead on the probe at high frequency makes anything you see on the scope suspect. You do still have those springy clips that come with the probes, which clip onto the tip's ground-ring? With your confession, I'd be expecting ringing on the signals you measured. That makes me wonder if your probe is properly impedance matched to your scope... Maybe time to test and recalibrate the probes on the 1kHz scope reference? -- Greetings Bertho (disclaimers are disclaimed) ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
