I built a signal generator based on ebay AD9850 card and a junk box encoder and an OLED 128x64 display. The code is mostly from Dean, KK4DAS signal generator. Some changes were done for display change etc. But the pins etc are more or less the same.

I noticed that when I increase the frequency, the peak-to-peak voltage reduces. The scope is a 50MHz scope. It could be that the frequency response is falling off or may be the probe is not good. But 50MHz could be the 3db point. So, there is something else going on. I will have to investigate what is going on...

I am also powering the unit with the USB from the laptop. That is awkward. I would like this to be a standalone unit. So, wiring up a power circuitry is the next in the agenda.

My code is available here. Next step is to use it to do the AGC experiments for Norcal 40a.