This weekend, I was testing the reverse recovery time of some diodes for a project. I decided to use my Siglent SDG1025 DDS because, you know, DDS! What I tried doing was setting the two channels to identical parameters (square waves at 1 MHz) to use one as a scope trigger. No matter what I tried, the outputs always showed some bad quantized jitter relative to each other. Here, I'm triggering on ch2 (bottom trace), and the jitter in steps of 2.5 ns is visible on ch1.

I played with the thing long into the night trying to get it to work correctly, but no. I even copied the parameters between channels using the channel copy function in the Utility menu. No dice.

I woke in the middle of the night wondering if this was a firmware bug. So, this morning, I grabbed the latest firmware and installed it. Of course, it turned all the menus into Chinese.

I found a document on how to fix this, and was soon on my way. The result: slightly less horrible broken-ness. It's still broken, though.

There really shouldn't be this kind of jitter between the two channels.

I've decided to make a dedicated tester for diode reverse recovery time. The edges on the SDG1025 aren't really up to the task, anyway.