The u.RAT with stepper motors bolted in and coupled to the variable capacitor and roller inductor
The two drivers and Raspberry Pi Zero W will be placed in between the capacitor and inductor. I have an Astron switching supply and a 12v to 5 volt step down component to supply the stepper motors and the Raspberry Pi Zero W.
The NEMA-23 steppers only draw .5 amp at peak load (tuning fast), and its lower than when I used a regular Raspberry Pi 3 b. I don’t know why, but I like it. I am pretty sure a set of NEMA-17 steppers and lighter duty drivers would do – what I have is way overkill, but I like that, actually.
The shaft couplers are really superb and are actually flexible aluminum, beautifully machined. Because they allow for a slight angle, the “purchase” seems better than straight through and with stainless steel couplers.
I expect that the wood does absorb some vibration that all steppers give off. So the problem of the set screws loosening is solved.
I have a pair of these and will probably mount them at each end of the roller inductor. They are perfect and I did find an easy to mount place. All they would do is turn on a red led that tells you that you are at the end of the roller inductor. They have exactly the right “play” before they switch on.