[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [TCML] RF Ground and Brass

In a message dated 3/5/08 10:08:05 A.M. Eastern Standard Time,  
Gary.Lau@xxxxxx writes:

>Your point about the wire not getting warm if it represents a high  RF 
impedance is well taken, but I 
>don't agree that gauging ground conductor suitability by spark  performance 
is valid.  Many coilers 
>have noted that performance is unaffected even when they  accidentally 
forget to connect the 
>secondary base to anything.  
    I'd have to strongly disagree with that  statement, based on recent 
    I had incredibly hot primary-to-secondary arcing  at the base of my 6" 
SISG coil until I connected the secondary base to earth  (via a length of 10ga 
stranded THHN). At first I thought it was the primary  arcing to the secondary, 
until I realized it was the floating secondary arcing  to the primary!
    Without grounding the base of the secondary  somehow, you've got a 
bipolar coil!
>The consequence of having a good or bad RF ground connection is not  
variable performance.  It only >affects how much RF gets  coupled into your power 
    I don't see where grounding the secondary or  not affects the power mains 
in any way. The issue is whether the return  current for the secondary has a 
sufficiently low impedance path to follow  that the secondary current will 
*tend* to not travel on  the power mains. 
    No matter how wonderful your RF ground is, if  you get a secondary strike 
directly to your house wiring you're gonna  have a problem. 
    The rest of the noise is coming back from  the primary or the power 
supply wiring. Secondary grounding doesn't matter for  this, but the quality of the 
RF ground that the Terry Filter, shielding, EMI  filter, NST/PIG/whatever is 
attached to would have an  effect. 
    None of this considers radiated RF from the  secondary, primary, spark 
gap or power supply. Neither does it consider  the induced voltages from the 
strong E and M fields near the  prim/secondary. 
> In the absence of a good RF ground connection, the only other  path to 
ground is through the power 

All that secondary capacitance has an  effective return path of "everything 
in the near vicinity". Grounding  your secondary doesn't affect it's 
capacitance change due to the proximity of  walls, ceiling, and the floor!
>That's what makes the topic of "proper RF grounding" so difficult to  
resolve.  There is no known 
>means of gauging success or  quality.

Your statement implies that grounding the secondary  has *no* perceivable 
effect. Otherwise, it would be measurable. If you can cause  a detectable change 
in quality, then improve it until you hit whatever point of  "too expensive" 
or "too much effort" suits you. FWIW, I think that for practical  purposes, we 
hit that point of diminishing return very quickly and easily. 
    You have to admit, running a piece of 18-10ga wire  to a desired RF 
ground is such a cheap and easy thing to do that  there's really no good reason not 
-Phil LaBudde
Center for the Advanced Study of Ballistic  Improbabilities

**************It's Tax Time! Get tips, forms, and advice on AOL Money & 
Finance.      (http://money.aol.com/tax?NCID=aolprf00030000000001)
Tesla mailing list