Forcing the SI5351 to above 1200MHZ VCO e.g. above 300MHz fundamental may overheat the SI5351 and permanently damage it.
So you should be EXTREMELY careful when using a threshold command with values above 300MHz.
Its like tuning a car engine. You may get a more performant engine but it also may explode....
Does that mean that if threshold frequency is set to 250 MHz then instead of 3 x 300 MHz = 900 MHz the operating limit will be 3 x 250 MHz = 750 MHz?
Yes and no, it means the nanoVNA will transition to 3/5 harmonics mode at 250MHz till 750MHz and use 5/7 harmonics mode above 750MHz.
All nanoVNA's with modern software can operate till 5 times the threshold value, whatever the threshold value is. The SI5351 may not lock (PLL lock error) or overheat if the threshold is too high.
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NanoVNA Wiki:
/g/nanovna-users/wiki/homeNanoVNA Files:
/g/nanovna-users/filesErik, PD0EK
