It works fine when you use 2 time bases and horizontal ALT.
With just one time base it works the way I said. Then with AC triggering it works regardless the relative vertical position of the traces, but this is tricky. When you separate the traces further (with one of the Position knobs) then also both traces get dimmer: after a trace switch the AC trigger coupling needs time to settle to the new DC level. With sine wave input in stead of square wave you should also see a horizontal shift in trace trigger points to the top of the lower waveform and the bottom of the upper waveform think (I didn't try).
Albert
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On Sun, Apr 14, 2019 at 02:05 AM, John Griessen wrote:
On 4/13/19 3:59 PM, Albert Otten wrote:
Hi John,
Step 19 requires that the A time base can be triggered from both 7A plugins
at one and the same trigger level. As you noted that was problematic and you
chose to set the level correct for the left 7A; hence the right 7A won't
trigger the time base; the sweeps stop unless you set AUTO.
Likely you use DC triggering. And you positioned the traces in the upper
half and in the lower half, so at quite different DC levels and hence trigger
output levels. What happens when you move one trace up or down, or when set
the time base for AC triggering?
Instead of trying AC, I tried another scope and it works fine, and the lights
say right vert A, and left vert A when in ALT and
ALT. That gives tow traces with different time bases. Here's a photo:
