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Show us your square wave
Grandchuck:
Here is a result from a Tektronix Scope Evaluation board and a Siglent DS2202. The board has a 4-bit counter with a risetime of around 2 nsec with some overshoot.
tggzzz:
--- Quote from: Grandchuck on November 11, 2023, 08:22:01 pm ---Here is a result from a Tektronix Scope Evaluation board and a Siglent DS2202. The board has a 4-bit counter with a risetime of around 2 nsec with some overshoot.
--- End quote ---
How was the probe's shield connected to the board's ground? A 6inch ground lead is a classic cause of overshoot.
Grandchuck:
Your guess is close ... it is a 5 inch lead. They put the ground pad as far from TP1 as possible???
I included a shot from the manual that came with the board.
joeqsmith:
That's funny to even see one of these boards. I picked up what appears to be the same one directly from Tektronix when I bought my first scope (Hitachi) back in the 80s. I think they were giving these away back then as a promotion.
Connecting from pin1 to pin4 using a LeCroy PP061 resistive probe with a pretty much dead battery, scope measure 1.65ns without the big overshoot. The BW is much higher than what you have available and there is no ringing. I also suspect your connection from the board to the scope.
tggzzz:
--- Quote from: Grandchuck on November 11, 2023, 09:50:35 pm ---Your guess is close ... it is a 5 inch lead. They put the ground pad as far from TP1 as possible???
I included a shot from the manual that came with the board.
--- End quote ---
Have a look at https://entertaininghacks.wordpress.com/2015/04/23/scope-probe-accessory-improves-signal-fidelity/
As a quick test I would wrap a length of wire around the probe body, with a short straight spike to the gnd hole on the left. In other words, a variant of the "spiked spring" supplied with the probe.
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