Any Tekxperts out there ?. I have a 2445 with a wierd trace problem. Trace 3 and 4 are fine, but 1 and 2 have a wierd modulation on them - independent of the attenuator setting but fixed frequency (changes with the timebase setting) in the ultrasonic region. Oddly, if the traces are positioned halfway up the tube, they are ok, but as moved higher or lower they get worse the further from centre. The amplitude gets less as the scope warms up but it doesn't go away. It looks like this :
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Any insights appreciated Cheers M