>The data sheet that I have for the PIC18F45J10 says 20Mhz
>crystals are OK and have been tested with the device.
>
>Table 2-2   page 26

But what does it say the PLL multiplier is, and at what input frequency does 
the PLL work?

IIRC the PLL will only do a 4x multiply, so you are limited to 10MHz input 
from a crystal. 

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