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Re: RF Ground, House Ground, Ground....



Original poster: "Steve White by way of Terry Fritz <twftesla-at-qwest-dot-net>" <slwhite-at-zeus.ia-dot-net>

Hello All,

I have been following this grounding thread and I think that some are
missing the point with the RF ground. What you want is a low impedance RF
ground. A low DC resistance is not sufficient. The DC resistance of the
house ground is typically very low but it not an adequate RF ground because
it has a relatively high impedance at typical coil operating frequencies.
Remember that the operating frequency of the coil is about 100 KHz. This
relatively high frequency needs a low impedance ground otherwise very large
voltage drops will develop along the ground conductor. The best cross
sectional shape for an RF ground conductor for low impedance at tesla coil
frequencies is a flat ribbon. The house ground should still be used for
tesla coil equipment that is expected to opertate at 60 Hz.

Steve: Coiling in Iowa

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, June 05, 2002 10:28 AM
Subject: Re: RF Ground, House Ground, Ground....


> Original poster: "Daniel Hess by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dhess1-at-us.ibm-dot-com>
>
>
> Matt;
>
> Sounds like your ground may be sufficient. You can test it by measuring
the
> resistance between the RF ground and the house ground. Ideally, I believe
> you want to read no more than 1 ohm. Mine tests out a 1.5 ohms but seems
to
> be performing adequately. I'm also running a 4 Ga. cable from the base of
> my secondary to the RF ground; even if the resistance between house and RF
> ground is low, too small a gauge cable may not handle the current and it's
> performance may suffer. If the resistance is too high you may have to add
> additional ground rods. I use six x 10 feet x 1/2" copper water pipe.
>
> Regards,
>
> Daniel
>
> "Tesla list" <tesla-at-pupman-dot-com> on 06/05/2002 09:12:53 AM
>
> To:    tesla-at-pupman-dot-com
> cc:
> Subject:    RF Ground, House Ground, Ground....
>
>
>
> Original poster: "Matt Woody Meyer by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <meyerml-at-stolaf.edu>
>
> Just for clarification sake, I'm curious if there's any major difference
> between
> the RF ground that you're all using and mine.
>
> My ground is simply a long copper tube driven a good 6-8" in very moist
> soil.  My
> protection filter and my secondary are grounded to seperate tubes, and
then
> a
> discharge rod (long wooden stick with a nail in the end of it wired to
> ground) is
> grounded to a third (Discharge rod used for discharging coil after
> operation and
> also for measurement purposes (never manually held near coil while in
> operation)).
>
> Is this an appropriate RF ground, or should I be doing something else?
>
> Thanks,
> ><>Matt
>
> ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>
> Matt "Woody" Meyer                  St. Olaf College Physics Major
>
>
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>