Greetings.
I have recently acquired a tektronix TDS654c oscilloscope, where I have found that everything works fine, with sampling rates under 25Msps, but once I go up to 25M, there is a periodic noise appearing on the signal, regardless of being in AC/DC/GND coupling, which looks to be around 250Khz. I have found online that this could be caused by a bad cap, so then I went ahead and replaced all the electrolitic caps in the PSU, which unfortunately didn’t solve the issue. I believe that this still could be a PSU issue (periodic noise suggests that), and hopefully not with the acquisition board. So this is where I’m stuck however, maybe a forum member has seen this issue, or could someone point to the right direction? Any help would be appreciated.
I have attached a photo of 10 and 25 Msps acquisition.
Thank you,
G