[TowerTalk] There's 'ground', and then there's 'ground'

[Pete Smith]

Fascinating, Frank.  I tried going back up the URL tree, and eventually 
found myself at a page for Presbyterian gun owners!  However, beginning at 
least with /ground2.htm there's a  lot of good stuff there.

The quoted info puzzles me, though -- my old farmhouse has lightning rods, 
and the cable between them and from them to the ground rods placed at 
intervals around the house is roughly 3/4 inch diameter aluminum, made from 
many ~#14 strands that are braided in a fairly complex pattern.  It is 
quite flexible and easy to work with.

When I went looking for home lightning rod suppliers on the Internet, it 
appeared that all vendors for this kind of service are still selling this 
braided aluminum stuff, and only this.

I guess I'm perplexed -- if it doesn't conduct lightning well, how can 
these people continue to sell it and stay in business?  I'd think their 
liability headaches would be phenomenal.

73, Pete N4ZR

At 10:50 AM 1/16/2005, Frank Donovan wrote:

>Hi Jim,
>
>Here's another one to add to your list:
>
>Discard all forms of "braided" cable. Braid is something a girl does to her
>hair.
>It is not a good RF ground and it's a terrible conductor for lightning
>energy.
>
>Use braid only for DC and audio applications, its just an inductor
>for RF or lightning protection applications
>
>Here's an excellent reference from the many industry sources on this topic:
>http://members.cox.net/pc-usa/station/ground5.htm
>
>73!
>Frank
>W3LPL
>donovanf at erols.com
>
>
>
>----- Original Message -----
>From: Jim Jarvis <jimjarvis at comcast.net>
>To: <towertalk at contesting.com>
>Sent: Sunday, January 16, 2005 6:56 AM
>Subject: [TowerTalk] There's 'ground', and then there's 'ground'
>
>
> >
> > 1)  I think you'll find that all unibody constructed cars
> > have serious anti-corrosion coatings applied, after welding.
> > Bolted-on components are almost never electrically connected,
> > unless there is a reason for it, as it represents both extra
> > work, and a breach of the corrosion protection.
> >     As the owner of two Passat's which had an ic706-2 installed,
> > I was careful to attach to the unibody when installing the
> > antenna.  Cutting holes is painful, though...as was the bodyshop
> > repair when I sold the vehicles.
> >
> > 2)  Most contemporary transceivers do not have a single point
> > ground.  There is a logic ground, an RF ground, an audio
> > ground, and a chassis ground.  They exist in different areas of
> > the radio, on different boards, and may be deliberately
> > separated from the chassis, for purposes of noise reduction.
> >     Yes, chassis ground shows up on the back panel.  And yes,
> > I would expect RF ground shows up at that point, too.  But
> > the logic and audio circuits reside internal.
> >     I think you'll find the mic 'ground' isn't the cable shield.
> > You'll also find that the 'shield' side of the mic audio connects to
> > chassis ground, on the PCB, via a resistor of 10 ohms or so.
> > There is usually a 'single point ground' for audio, which references
> > that circuit to chassis, and prevents ground loops. The mic element
> > itself is usually floating within the housing.
> >
> > 3) External audio processing equipment requires particular care
> > not to create ground loops.  As someone observed, pro-audio folks
> > put real effort into that, in their equipment.
> >
> > 4) One could write a volume on proper grounding and shielding in
> > the mixed signal environment presented by a hamshack.  And I won't.
> > At least not here.  Just one sentence:
> >
> > SAFETY GROUND SHOULD BE TESTED.  SPEND 10 BUCKS ON A 'PLUG CHECKER',
> > AND TEST ALL OUTLETS THROUGHOUT YOUR HOME.  YOU MAY BE SURPRISED,
> > PARTICULARLY IF YOUR HOME WAS BUILT IN THE 60'S, OR HAS ALUMINUM WIRING.
> >
> >
> > n2ea
> > jimjarvis at ieee.org
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
> >
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>
>_______________________________________________
>
>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
>any questions and ask for Sherman, W2FLA.
>
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