Re: Can anyone diagnose problems with our coil? (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Mon, 11 Dec 2006 19:37:00 -0800
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Can anyone diagnose problems with our coil? (fwd)

Hi John,

We would be happy to help, of course. But, give some higher detail about 
your coil. Coil geometry of both secondary and primary circuits are very 
helpful as is the top load type, size, and position. The transformer 
sounds really small. The mA rating would be helpful (and may be the 
biggest issue your having).

I am not one who likes grounding to the safety ground. RF ground really 
should be dedicated if at all possible. Even a metallic plate under the 
coil would be better than tying the RF ground to the safety ground. A 
plate or wire mesh below the coil is a counterpoise of sorts. A 
counterpoise can affect the resonant frequency of the coil, especially 
if it's small, so retuning is certainly necessary but never a big deal.

Take care,
Bart

Tesla list wrote:

>Original poster: List moderator <mod1@xxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Mon, 11 Dec 2006 15:03:05 -0800
>From: john welch <jowelch@xxxxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Can anyone diagnose problems with our coil?
>
>My student assistants and I just built our first coil. It kind of works, 
>but we are getting little tiny streamers coming out from the top of the 
>secondary coil and nothing from the ball on top.
>We have tuned the circuit fairly carefully so that their resonant f's 
>are very close. We have a multiple spark gap made of copper pipes. We're 
>using 2 Condenser Products pulse discharge caps in parallel to get .01 
>mF rated at 10,000V. We have a 6000V neon sign transformer.  We are 
>grounding the secondary to a wall outlet ground - I've heard not to do 
>this, but am not sure why and can't find much else to do indoors, and 
>many people tell me that that's what they do.  Our secondary coil is 
>22ga magnet wire around 3" PVC. The top end of the 22ga wire is 
>connected to the ball, and the bottom end to a 5 foot length of 10 ga 
>wire that I stick in the "3rd prong" of an outlet. Our primary circuit 
>is the transformer directly across the spark gap, and the (cap and coil 
>in series) also across the spark gap. We plug the transformer into a 
>variac, and have both a line RF filter and a power factor capacitor.
>Any advice would be greatly appreciated.
>thanks
>-John
>
>  
>