TDS6XX / 7XX waveform help needed,

[CaptDon]

Is there a way to change the sample rate for the slower sweep speeds?
My TDS644B is great for looking at USB rise times and so forth but I have
run into a snag at slow sweep speeds as follows,
I have a 1mhz RF sinewave that is AM modulated by 1khz. As we all know
that waveform should look like a bunch of ovals standing on their ends
and then their sides touching each other. When I slow the sweep down
to maybe 200us or even slower the 1mhz gets aliased to uselessness!!!
I can get a perfect expected display on my older SC502 analog scope but
can't get anything useful on my TDS644B or even my TDS2004B for that
matter. Have any of you found a way to display such a waveform on an
older digital scope??  Thanks!!

[wn1fju]

At least on my TDS520, which should be similar, you can put the acquisition mode into Peak Detect (Envelope might also work OK).  You can also adjust the holdoff in the trigger menu.  That should get you a stable display like it would look on an analog scope.