Re: [TenTec] grounding

[Martin AA6E <aa6e@ewing.homedns.org>]

The question is whether your "ground" wire carries an appreciable RF 
current.  If it does, and if its length is a significant part of a 
wavelength, it will radiate.  There's no avoiding it.  Your "zero 
impedance" tuned ground will still be carrying current.
If your antenna is balanced so that the ground wire does not carry an 
appreciable current (in Tx), then you may not need it for RF purposes. 
It may still help in a marginal situation, but your AC/lightning 
protection ground may be good enough.
73 Martin AA6E

Gary Hoffman wrote:
> Let's say for sake of discussion that you have a shack position close enough
> to physical earth (and your array of ground rods and buried wire) that you
> can have an excellent, much less than 1/4 wave ground, made of broad strap,
> at all frequencies except 10 meters.  So, for 10 meters, you use a tuned
> ground strap centered where you normally operate.  It seems to me that this
> "longer" ground strap will not become a radiator at the lower frequencies
> because it is in parallel with the real short strap, and thus is effectively
> "shorted out" RF-wise by that short strap.  Not so ?  If one has several
> impedances in parallel with a short circuit, is not the whole thing then a
> short circuit ?  And hence a zero (well, close to zero) impedance ground ?
>
> 73 de Gary, AA2IZ
>
>
> ----- Original Message ----- 
> From: "Martin AA6E" <aa6e@ewing.homedns.org>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Tuesday, January 09, 2007 9:52 PM
> Subject: Re: [TenTec] grounding
>
>
> > M. Todd Miskel wrote:
> > > Doesn't a good earth ground help remove stray RF from the shack? along
> with
> > > ferrtie cores etc...
> > Ferrites can help, but if you really want a "good" RF ground, it should
> > be less than about 1/10 wavelength long at the shortest wavelength you
> > want to use.  So about 3 feet in the 10 meter band!
> >
> > If it's not that short, it can be "tuned" to be an integral number of
> > half wavelengths at any one particular operating frequency... but then
> > your "ground" lead becomes part of your antenna system. It will radiate
> > and receive.
> >
> > So it is good advice (as someone said) to be sure your antenna is well
> > balanced and as far away from the shack as possible.  In that case, the
> > RF ground is usually not needed. But a good AC & lightning single point
> > ground system is still important.
> >
> > 73 Martin AA6E
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec