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Re: [TCML] Fw: Massive Vttc!!!



Hi Carlos, I think the secondary winding direction only maters if the tickler coil is way above the primary. I have never operated a VTTC in true CW mode before so I think I would be interesting to see you coil in operation. My largest tube coil is based on the popular 833 VTTC design but it uses a 3CX2500f3 instead of a 833. This style of tube coil typically has 20 to 30 turns in the primary, tight coupling and the tickler coil is high above the primary which I believe allows it to run in step with the actual secondary resonant frequency. The first tube coil I ever built was a loosely coupled one like yours and I was able to make it work pretty good but one advantage to the more popular tightly coupled designs is that you can make them a lot more compact and you can use smaller wire in the primary coil.

I would have to agree that experimenting with pulsed modulation might be a good idea although it might be hard to do with such a large system. For what its worth here is a link to a video of an earlier version of my VTTC. http://www.youtube.com/user/RogerInOhio?feature=mhum#p/a/u/1/ea5t8OMLutg

Roger
----- Original Message ----- From: "Carlos Van Camp" <carlos@xxxxxxxxxxxxxxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, November 05, 2010 2:14 AM
Subject: [TCML] Fw: Massive Vttc!!!





Thanks for the tips.
For those that requested more information, here it is:

Primary 3/4" copper tubing, 10 turns tappered first turn 20" diameter last turn 30" with 1/2 inch between turns.

Secondary is 10 ft long and 16" diameter, 5 turns per inch, 600 turns.

Tank cap is 0.0168uF (ceramic) rated 60kv 300A rms.

Valve is 4CX15000A.

It is configured as an armstrong oscillator with a "tickler coil" at the base of the primary / secondary (currently 1 turn of 1/4 inch tube...)

Power supply is 10kv 5A DC from a 3 phase transformer rectified with 6 diodes.

The coil is also audio modulated which is why we chose to use rectified 3 phase for the power supply (smoother DC means less distortion to the sound)...

For this we use an audio transformer connected to the screen of the tetrode, and a 500 watt audio amplifier connected to an Ipod or similar.

During most tests we have only been running a variable dc supply on the screen 0-750v, so we can control the output gradually. Although the system is good for 50kw continuously, we have only run it upto 35kw. At 20kw input the arcs are about 2 ft long, and at 35kw they gain about 6" and just get fatter... I am only running 0.1A on the grid although the spec says 0.28A for full class C. I have run it at 0.28A grid current. The arcs turned orange and became more flame like, but they also got shorter, so I went back to the lower grid current...

Thanks for the tip about considering the winding direction of the secondary coil to the tickler coil... I will have to check this, however my tickler coil is at the base of the coil, so I'm not sure if it would matter or not...?

The other thing that has been on my mind is the lack of turns on the secondary... I know with standard coils the turns ratio is not so important, but I am wondering since this is CW if the turns ratio may be more important...?
Any comments about this?

Thanks,

Carlos

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