ADF4351 with Arduino and rotative encoder 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.