Re: [TCML] Run coil in mall

[jhowson4@xxxxxxxxxxx]

Could not have said it better my self Jim! 



Thanks, 
John "Jay" Howson IV 


"Why thank you, I will be happy to take those electrons off your hands." 

----- Original Message -----
From: "Jim Lux" <jimlux@xxxxxxxxxxxxx> 
To: tesla@xxxxxxxxxx 
Sent: Tuesday, February 14, 2012 7:49:21 AM 
Subject: Re: [TCML] Run coil in mall 

On 2/14/12 2:50 AM, Jim wrote: 
> Thanks every for the good replies. 
> 
> John, what is the difference between a RF ground and earth ground? 
> 


Rf ground is "the cold end of the secondary" and doesn't necessarily 
need to be earth ground "the ground you're standing on". 

>From a spark standpoint, there's no need for the secondary of the TC to 
be connected to physical earth: consider a jacob's ladder on a NST.. 
plenty of sparks, no physical earth connection. 

>From a "tuning" standpoint, the screen under the coil (or earth) serves 
as "the other plate" for the topload capacitance. 


There's several reasons why you want some connection between the "bottom 
of the coil" and "the earth you stand on". 

One reason is safety.. if someone is going to touch that ground screen, 
then you want it at "earth" potential. Likewise, if it's not at "earth" 
potential, charge can accumulate and you could get a spark from screen 
to ground, possibly somewhere it would be bad to have it. 
This connection can be high impedance (i.e. you don't need a big strap 
or cable.. it could even be run through an RF choke). 

The other reason is that unless you're running in a full cage, your 
screen might be 95 percent of the "capacitor" but the surroundings 
around the coil will be the other 5 percent. You want the connected 
together because capacitive coupling can allow current flow and you want 
the current going somewhere predictable. 







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