Re: Birdie at 7199 - a surprising observation!
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Here is a picture at the output of Si5351 not connected to a mixer, just terminated with 51R resistor. This happens when the output is different from 25MH. Only CLK0 is enabled. Quartz at 27MHz. The spurious "needles" in the spectrum appear to be related as follows: ¡À±·*4*´¥³Õ¹ó°¿-25²Ñ±á³ú´¥
And apparently these are not the harmonics of the fundamental VFO frequency. This is rather disturbing because they appear blow and above the fundamental. No wonder I have numerous birdies. Suspiciously 25 MHz is 800 MHz (PLL) divided by 32...
I wonder if decoupling the different supply pins of Si5351 might help. Another thing I might tryis to buffer the CLK0 with a fast logic gate with separate low noise power supply.
73 de LZ1NEF
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