Re: Tuneing A VTTC

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Adam,

My tube coil has the same basic layout as yours (I have dual 811A 
tubes).  I found that the primary (L1, C3) were tuned almost exactly to the 
secondary (L3 + topload) frequency.  I added a parallel variable vacuum cap 
to C3 and found that the real best point was with the frequency of the 
primary tank about 2% lower than that of the secondary (probably accounting 
for streamer capacitance).  However, the difference is very small and 
almost a "don't care".  The frequencies should be measured with the 
secondary and all in place as if the coil were operating.  If I remove the 
secondary, all the measured frequencies go haywire.  I don't think the 
weather or surroundings would affect things in the least so don't worry 
about that.

FYI - I also measure the input power to the coil at the maximum 
"recommended" sustained power level and got:

Input voltage = 113.1 VACrms
Input current = 10.17 Arms
Real power = 1062 watts
VA = 1135 VA
pf = 0.92

0.5 amp was for the tube heaters.

Cheers,

         Terry

At 04:14 PM 9/29/2003, you wrote:
>Hi Guys,
>
>I am very close to first light with my coil know just awaiting a MOT (I
>never knew these things would take so long to source!)
>
>Any ideas how I tune a VTTC?
>
>How critical is tuning on a VTTC? What sort of conditions should tuning be
>done in? I work in a cold and damp garage as a workshop so dont know if
>these are the correct condtions for tuning. Would tuning the coil in my
>house be a better option?
>
>The design I followed is here
>http://hot-streamer-dot-com/srward16/images/dual%20833A_gif.jpg
>
>Adam