I feel like a total newb here, because I've built resonant tank circuits plenty of times before, but somehow I'm stumped on this one. I've run into a bizarre problem I can't figure out.
See scope shot:
The top channel is my signal to the gate of a mosfet. The mosfet is driving a tank circuit that contains a large coil wrapped on ferrite with a 5uF capacitor. The coil is large enough that the frequency is near 100Hz.
The bottom channel shows the positive side of the tank capacitor where the mosfet source is connected to drive the circuit. What I'm confused as heck about is the low voltage delay after the input turns off and before the initial oscillation begins. I don't recall ever running into something like this before. I've traced my circuit leads and double checked everything and I just don't know what's going on. Anyone else ever seen something like this in a tank circuit?
Ok here's a circuit diagram. I should have posted before, but I doubt this is going to help: