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There has been some debate on having attenuators around the mixer, it is even suggested it may reduce spurs.
So I did test.
First picture is a scan of the 15MHz power calibration signal with 6dB attenuators between LO and mixer and mixer and BPF

?

Second picture without any attenuator



Signal improved with a bit more then 6dB and noise a bit less so the attenuators are NOT improving the noise level.
The spurs reduced both in absolute level and even more compared to the 15MHz signal (keep in mind the levels indicated are relative to the strongest peak, in this case 15MHz)

My guess is the spurs I'm seeing are caused by harmonics of the power calibration signal directly getting into the signal path after the mixer.

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HBTE Files section:?/g/HBTE/files
Erik, PD0EK

Erik,

I didn't chase it, but when I looked at my 10mhz reference with a scope
and set the trigger a little bit high, I saw some occasional disruption in the 10mhz.
Could be that the Si4432 doesn't do a clean divide-by-3 of the 30mhz reference,
as it is attempting to create a 50% duty cycle square wave.
And that setting up register 0x0A for 15mhz instead of 10mhz will be much cleaner.

Or I could have just been seeing trash due to layout issues.

Jerry, KE7ER

That noise on 10mhz is not seen when probing the GPIO2 pin.