Today I have build a working "proof-of-concept".
After I thought I had broken the AD9850 module, I found out that I only forgot to connect D0 and D1 to 5V line... Now the AD9850 is controllable from the ESP8266 via WLAN.
Now the ESP8266 connects to my WiFi and you can change the frequency via an very quick and dirty webpage... That you can see here:
When you type in your desired frequency, the ESP8266 will process it and changes the output frequency of the AD9850.
In the files you will find a early schematic draft that I used as basis for my experimentation setup.
Here can you see an video of my experimentation setup and some little tests of changing the frequency:
The next few days I will try to improve the setup and the webpage, also I want to start writing an Android app for controling the DDS. Furthermore I will test some HF amplifier circuits to improve the output amplitude. And last I will try to implementate the "wobble" function, so that you can plot filter curves of components like HF-Filters.