This project was built to get my mag loop on the air and is just an Arduino UNO controlling a stepper motor. I should mention that this is set up for a Trombone Capacitor and requires a LOT of revolutions to get it to cover from 40M to 30M to 20M. So the code will have to be modified to change the stepping regime. There is also only one end stop function which may need to be removed if you are using a continuous variable capacitor.
As I have dis-assembled the project to build a better one these are all the pics I have of it.