Who does not want a VNA and/or Spectrum Analyzer? I do, but those are a bit out of my budget right now. But I still want to play with some loop antennas for the project that is in the works, so I need a way to measure loop antenna parameters. How is it done? Well, you put known signal into loop and measure response, that’s what VNAs and SAs do, but those are expensive…
Cheap AD9850 breakout to the rescue. China made AD9850 breakout boards are available on eBay for ~6USD shipped (I wonder how they do that if chip itself costs ~15USD in 1000 quantities from DigiKey). Those things are capable of putting out 0-40MHz in sub-Hz steps of quite nice and clean sine wave, but you need a way to control them. And so “somewhat useful” Arduino sketch was born. It uses AD9850 library from ELECFreaks, one can set specific frequency with it, make AD9850 sweep through frequencies tracking generator style or sweep through frequencies in oscillating manner – back and forth.
It is probably good for testing AD9850 breakouts too, enjoy – somewhat useful AD9850 Arduino sketch.
A bit of background info. Serial control is used, see the datasheet what pins need to be pulled up and what pin needs to be pulled down to enable that and since there is no information on module available, some nice guy called Andrew Quinn has documented pinout of these little neat boards on his blog.