My 833A VTTC

[MRMILSTAR]

I finished this VTTC in January 2018. Its based on a single 833A vacuum tube. Salient features are:

1. Completely self-contained
2. Open-frame construction for viewing and ease of maintenance
3. Single large MOT with voltage doubler to 4000 volts
4. Single NOS Amperex 833A vacuum tube
5. Resonant frequency is 361 KHz
6. Primary is 8 AWG THHN stranded wire with my own unique tapping method
7. Filament voltage is controllable by a dedicated variac
8. PFC is used to minimize wall current
9. Has built-in interrupter circuit
10. The base plate is a solid 0.5 inch aluminum sheet

The VTTC produces 20 inch streamers in interrupter mode. The picture showing it operating in the dark has my ion spinner mounted on the discharge electrode. The first three photos were taken by Bill Fox at the 2018 Mid-Ohio Teslafest.

[T3sl4co1l]

Nice!

Tim

[kilovolt]

Steve, that is really an awesome coil! Very nice build indeed! I would love to work one day with a 833 Tube. I built a VTTC with two GU81M abot 10 years ago, but never worked with 833 before.

Best regards
kilovolt

[Mads Barnkob]

Very high quality build!

I like the primary taps and copper tubing for the primary circuit parts.

If the 833A easier to drive since you have so few feedback coil windings? Looks like 8-10 or is it just really high coupling?

The PFC you mention, is that passive PFC?

[MRMILSTAR]

Very high quality build!

I like the primary taps and copper tubing for the primary circuit parts.

If the 833A easier to drive since you have so few feedback coil windings? Looks like 8-10 or is it just really high coupling?

The PFC you mention, is that passive PFC?

Thanks Mads and kilovolt.

I started with about 20 turns on the feedback coil but I gradually started removing turns to move the coil lower on the form. I assume this is because my coupling is very high. I am currently at 14 turns. I would like to move the feedback coil even lower to get it further away from the top of the secondary coil to avoid arcing between the feedback coil and the secondary coil. That is why I added the acrylic spark shield that can be seen. I don't want to remove any more turns until I can actually measure the feedback voltage. I need a HV differential scope probe to do that. I will soon be buying one.

With regard to the PFC, it is passive. I can enable or disable it with a switch on the front panel. As I recall it reduced the wall current draw by about 4 amps.