Re: Help with TC

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 1/11/02 4:18:42 PM Eastern Standard Time, tesla-at-pupman-dot-com
writes:


>
> Hi all,
> I have several TCs that I have been working on for quite a while, and
> it seems that I can never get arcs nearly as big as people have said
> on webpages, on the list, etc. for the same input power.



Sean,

Well you don't mention the actual spark length you're now 
getting, but in any case, it's not surprising the sparks are shorter
than they should be because you don't have a topload.  A topload
is very important and can almost double the spark length.  More
below.


>
> Currently, I am running a coil with two 9k60 NSTs in parallel, a PE
> homemade cap of 35 nF, 3/8 copper tubing for the primary, and 22 AWG
> wire for the secondary on a 4" PVC form, about 28" tall.  The primary
> is an inverted cone, about 30 degrees, and has about 10 turns (should
> be more?). It seems like I can only get it to run somewhat well if the
> primary is tapped all the way in at around 2 to 2 1/2 turns, and wont
> run well anywhere else.  



Well since you're using rather thick wire on the secondary, this
lowers the inductance and forces you to tune at 2.5 turns which
increases your gap losses.  This too hurts the output spark length.

I don't have an output terminal, and I know

>
> this would lower the operating frequency, and then I would have to tap
> it out farther.  Also, do the wire lengths from the cap to the primary
> make a huge difference? They are 10AWG, but are about 3 feet long
> almost, 



That won't matter much provided you use thick wires to the caps.

as my cap is in 4" PVC, a rolled type, so the terminals are

>
> fairly far away. I just bought 12 0.05uF -at- 10KVDC caps for a MMC. 
> Will this help a lot? 



It depends on what material you are presently using for the rolled
caps.  If you are now using polyethylene, then the MMC's won't
help the spark length.  If you are using Mylar, or other inferior
plastic dielectric, then the MMC's will help.

Cheers,
John

I am using a RQSG, with 9 sections, and a fan to

>
> quench the spark.  What else could be improved, or what more
> information is needed?
>
> Thanks for any help anyone can provide.
>
> Sean Taylor
>
>