Juan -- I took a quick look at your .wav file and see this:

The tone peaks @ 600 Hz and there appears to be phase noise sidebands down ~ -60 dB for a range ±200 Hz. I tried a number of different windowing functions -- this is Hanning. I believe all the low-level spikes are merely due to aliasing/overload.

I'd very much like to see a full I/Q "IF" sample.

BTW -- I do my screen captures like this with Pixelmetrics' "Capture Wiz Pro" that I keep resident all the time. Incredibly useful tool!

73, Tom