oneTesla

Looking through the user manual, I noticed that the gate drive resistors were 6.8 ohms, and the tank capacitor (the film one) was 0.068 uF. Is this an important relationship? In the "Help" section, you guys say that the resistance must be 6.8 ohms +- 5%, but is that just because of the tank capacitor's capacitance. If, for instance, I already have a high voltage fast switching capacitor with some other capacitance, can I use it? Will I need to modify the resistance of the gate drive resistors? And while I'm asking, why do we even gate drive resistors?

I don't see how they are related except for the number, i assumed these resistors were there to prevent the gate drive ic's to burn out and maybe prevent some funny business in the gate drive transformer (i expect the IGBT to act somewhat like a capacitor).

I am quite sure you can switch out the capacitor, however remember that this is one part in the resonant circuit so you will probably need to change the windings of the coil. Also i expect some components are selected for a certain frequency (higher=more skin effect, and heavier on the zero crossing, lower i would not know).

I might not be spot on so listen to the people after me.

the gate resistor is to slow down the speed at which the IGBT turns on, while the tank capacitor size tunes the coil.

It's just a coincidence

It makes sense that I could switch out the capacitor (which is great, since I already had a resonant spark gap Tesla coil to work with), but don't we want the IGBTs to turn on as quickly as possible? If we switch them when there is no current in the primary really quickly, then there is less resistive heating, right?

to a point, but if it turns on too quickly you will get ringing and voltage spikes at the IGBT.

This page explains it well:
http://www.loneoceans.com/labs/drsstc3/