I've never heard the term "padding capacitor" and I had to do enough digging to lead me to believe it is a largely unused term in modern times. I did find this page from an April 1964 edition of some magazine (given the url, I think it might have been called "Radio Constructor".
This, assuming it is using the terms as they were widely accepted back then, would indicate that the timmer cap is in parallel with the inductor. But it shows the padding capacitor to be in series with the inductor, and NOT in series with the main tuning capacitor.
Regardless of what they used to mean, it would make sense to me that a "trimmer" capacitor would be used to shave off some capacitance while a "padding" capacitor would be used to add a bit. But there are plenty of terms that are used in ways that don't make obvious sense on the surface but, when you find out the mindset when they were originated, so make sense within that context (and sometimes they still don't).
This, assuming it is using the terms as they were widely accepted back then, would indicate that the timmer cap is in parallel with the inductor. But it shows the padding capacitor to be in series with the inductor, and NOT in series with the main tuning capacitor.
Regardless of what they used to mean, it would make sense to me that a "trimmer" capacitor would be used to shave off some capacitance while a "padding" capacitor would be used to add a bit. But there are plenty of terms that are used in ways that don't make obvious sense on the surface but, when you find out the mindset when they were originated, so make sense within that context (and sometimes they still don't).
