I have made some modifications of ADF4351 OE6OCG Arduino sketch:

• Using rotative encoder instead push button’s.
• Add a STEP button with 10M/1M/100K/10k/6.25k step’s size. (you can use push of encoder)
• Add a Band button to load 35/50/145/435/1240/2345/3000/4400 frequency.
• Using a LCD 2×20 with I2C <LiquidCrystal_I2C> libraries.

My test was done with the ADF4351 SV1AFN Board,

DONT FORGET TO INSERT A LEVEL SHIFTER BETWEEN ARDUINO AND ADF4351 BOARD, (for my test i have used Arduino NANO @8Mhz 3.3v, so, don’t need).

Code is dirty and need’s clean-up, but work, available here.

UPDATE 8/12/17: Bug with 10Mhz Step size is fixed.

http://www.f4huy.fr/wp-content/uploads/2017/02/ADF4351_Rev02.zip