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

["Roger Smith" <rwsmith@xxxxxxxxxxxxxx>]

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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