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Hi, I was measuring my power supplies, and found that the trident output powering the XO has a 12.5MHz ripple on it's output (hopefully I read/calc it correctly). As this is 1/8 of the XO freq, I'm wondering it has anything to do with it. Is this normal, or should this be just as clear as the other tridents? Thanks, igy Edited by user Friday, July 24, 2015 10:46:21 AM(UTC)
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Hi Igy. When measuring are you using a grounding spring ? (like this grounding spring) Edited by user Friday, July 24, 2015 2:13:15 PM(UTC)
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I used the standard tektronix probe of the scope (http://www.tek.com/datasheet/passive-probe/p6139b-%C2%B7-p5050b-0). I used the clip, not the spring. (Clip to the trident gnd, probe tip to triden out pin). I also tested the other tridents, they're clean with the same setup. (Except my avcc, which shows the ~260khz triangle wave noise issue, discussed elsewhere on this forum). Edited by user Friday, July 24, 2015 2:01:02 PM(UTC)
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Try using the spring to see if it makes any difference.
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I'm not sure it'd make a difference; if it's some external noise picked up, I'd expect this to be present in the other tridents' measurements, and none of them showed this.
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Sounds logical. You might be right.
My experience is I can't measure anything without the spring. Environment is just too noisy.
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Yu also have to watch for loops between the scope and the device under test. AC - transformer coupling can help there.
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