I'm using 3.3V Arduini Pro Mini to program adf4356 through SPI interface. I'm getting a fixed 4.6GHz signal from the chip and I'm able to change the output power level of the chip among four different levels. However, I can't change the output frequency by changing the 10 bit R counter value or integer value (I'm using adf4356 as an integer-N PLL). Does anyone know what might be the reason? Any suggestion or reply will be appreciated.