Hi Ernst,
I have the exact same 300MHz, 600MHz peaks. I'm actually trying to full charge the battery before making any measurement. I suspect the LiPo switching battery charging circuit to generate this harmonic. I will see if I have the same signal signature right after a full battery charge.
I have the white Gecko version on which I added 3 cavities over the mixers circuits. (see my other post with pictures).
Regards.
Georges.
