Thank you Hank for your excellent explanation. The traces do indeed
stabilize if I bring them together. I was just expecting a stable
display with the same signal going into both channels. Looks like I can
close it up and call her done!
--- In TekScopes@yahoogroups.com, HankC wrote:
the trigger circuit includes a lower freq square wave, which is a
composite of the trace position of the 2 signals.
This lower freq square wave gets differentiated by the AC coupling tothe trigger circuit.
So, the trigger sees a differentiated spike with the vertical signalsriding on the differentiated slopes.
Note that the trigger instability improves when you position the 2traces closer together.
This is because the "square wave" component of the trigger signal isbeing reduced in amplitude.
Trigger off either of the signals & the problem will go away.rate is much faster than the Alt rate.
So, it doesn't get differentiated by the AC coupling to the triggercircuit.
You will not findLF trigger mode on a single-trace scope.