On Wed, Apr 17, 2019 at 03:46 PM, John Griessen wrote:
20 ns is usually solid
You seem to say that it too sometimes displays the same behaviour, which is only natural, as may be deduced from what I wrote earlier.
You are looking at a very slow ramp/edge, triggering a time base at about its top speed at almost top amplitude level with a vertical sensitivity of only 2 mV / div.
Such a slow ramp provides very little information in your measurement setup. It may be an interesting experiment.
It is possible that some imperfect/varying contact causes the effective trigger voltage to vary by a few 100 microvolts, which would cause the behaviour that you see. If you'd see the same effect with a steeper slope with a larger amplitude at the same time base speeds, *that* would mean something and would point specifically to a problem in the time base.
Raymond
Raymond Domp Frank