Hello, i built a dual 811a vacuum tube tesla coil using steve wards VTTC 1 design. My build does not work. Can someone please look over my circuitry and check it against the schematic below? however shoddy my connections look they are solid and tested. I am inexperienced with electronic schematics but know how to be safe with high voltage. Anyone with tesla coil experience could please help me with this? My vacuum tubes light up and my primary seems to be getting power, but no sparks on the secondary. I have tried swapping connections on all the coils and have ran out of ideas. Any help is welcome, thanks.

 

If the circuit is not oscillating, try reversing the connections to L1 or L3.

 

Just wondering why the HT rail is not provided with a Diode, from the mot, DC supply !?

 

1.8 nF cap, 6kv seems to be 3 caps in series. Capacitance will be 1/3 of cap values. Are you sure it is 1.8 nF total capacitance?
C1 seems too small to be a 20kv cap, looks more like a 6kv.

 

Another note, the 811A should not run with 2000V on the plate, normally they run in the 1500V range, sometimes 1750V in intermittent service. As well, that is DC voltages. 2000V AC would have peaks of over 2800V, which could cause a flashover in the tubes. If you have the variac on the input, keep the plate voltage low enough to operate properly. Also, I don't see how AC plate voltage will work properly, it should be DC voltages to create an oscillating circuit. Where did that schematic come from?
Other schematics show a MOT HV diode and a small filter capacitor:

https://kaizerpowerelectronics.dk/w...-240x180x100-00f0w010c011r110f110r010t010.gif