On an MSO1104Z, I saw serious jitter on a 100MHz, clean sine wave. It seemed to happen after having all 4 channels active and then turning off the other 3.
Nothing would make the jitter go away until I pressed AUTO. After AUTO was done, I had to turn off channels 1-3 since my sine was on 4. Now the jitter was gone.
Along with this, I discovered that the frequency counter is BROKEN. Again, with a clean sine (57.000MHz, 90.000MHz), the frequency will read high or low, by a huge error, as you adjust the trigger level, all the while the sine remained cleanly triggered.
The frequency appears to be correct only when your trigger line is close to the zero crossing of the waveform.
Den