Vacuum tube tesla coil (VTTC) using Russian GI-30

A nice and compact setup, that works off-line, directly at 220V, with only a voltage doubler to get the plate voltage up to 560V DC. I don`t need to go into details explaining this circuit, it is a simple Armstrong oscillator, using the feedback coil L4. Here is a great tutorial detailing all the basic knowledge and know-hows behind a VTTC. My goal was a compact design. I`ve used a 220V ATX PC Supply connector
Vacuum tube tesla coil (VTTC) using Russian GI-30 - schematic

, a switch to power the tube, and another one to select the filament voltage (under-nominal and the nominal 12. 6V values). Careful, the voltage must be 12. 6V with the tube connected! I then tried various combination of secondaries and primaries coils, with variable number of turns or coil diameter, and adjusted the capacitors to get the best spark, RF emission, and power level. This took some time, but it was an important step in the construction of this VTTC: It can be seen the last coil is a winner. Also it is more compact than the other 2, perfect for my setup. I had to wind it manually and this also took time, but at least I could use it successfully. For the final setup I had to move the electrolytic capacitors, and cover them with another piece of wood to make some space for the coil and oscillator and feedback caps, on the same base. Got this nicely done:

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