Thanks for the comments. My comment to Martin about a direct strike is,
'Forget it'. In the case of a direct strike, there is no system that will
absorb it. You can mitigate the damage, but you cannot prevent it. That's
from experience where I had a direct strike on the tower that turned
antennas to molten aluminum and fried everything in the shack and the house
in general. By the way, take a look at Martin's web site and what he has
done. Pretty impressive. Thanks, again.
Jim, K4ZMV
----- Original Message -----
From: "Martin, AA6E" <martin.ewing@gmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Tuesday, November 29, 2005 10:54 AM
Subject: Re: [TenTec] Station and AC Ground
> Jim,
>
> I'm surprised your grounds are equal "to the microvolt". To me, that
> indicates that no current is flowing in either, not even reactive, or
> else they really are bonded together in some way. A practical ground
> is going to have a resistance of a few ohms, in my experience. And no
> two independent grounds will have the same resistance. So a current
> of even a microamp will produce microvolts of differential.
>
> That's neither here nor there. The thing to be concerned with is what
> happens under fault conditions. What if there's a short in the wiring
> that delivers 100 amps into the protective AC ground? (Let alone a
> lightning event.) Under those conditions, you want to be sure that
> your ham gear is not in the loop. If your 3rd wire AC ground goes to
> your rig, and your local radio ground is separate, you'll get a good
> fraction of the fault current going through the radio. Bad!
>
> I solve this by running all my station AC through a Polyphaser PLDO
> protector, which is bolted to my single point ground plane. That's
> where the 3rd wire AC meets my ham ground system. I observed a
> fraction of a volt of AC between the grounds before connecting them.
> Now, any current surge will go from the 3rd wire to the SPG and my
> equipment should not see it. See
> http://blog.aa6e.net/2005/03/in-shack-ground-system.html .
>
> (The PLDO is there mainly to absorb voltage surges on the hot and
> neutral wires, not for grounding, but it does add discipline to the
> grounding situation.)
>
> 73 Martin AA6E
>
> On 11/29/05, JAMES BRASSELL <jimbrass@bellsouth.net> wrote:
>> Hey, All.
>>
>> Just a quick observation and question. I have read many posts on this
>> site about having the station and AC mains grounds tied together. For my
>> observation, when you have a separate station ground (and I do; a good
>> one) and all pieces of equipment are tied to that ground and the ground
>> wire from the AC plug is tied to the equipment chassis then you have
>> effectively tied the AC mains ground to the station ground. I have
>> measured from the AC mains ground to the station ground and it is zero
>> ohms, with no voltage (to the microvolt between them). I have looked in
>> the equipment and the AC ground is tied directly to the chassis, not
>> through a board. My question is, if the equipment is grounded and you
>> have a good AC mains ground is that not tying the mains and station
>> grounds together? I could see where one might have a problem if the
>> ground in the equipment was achieved through a circuit board and the
>> equipment was not otherwise grounded. I feed two verticals, GAP Titan an
> d
>> Voyager, and run 1500 watts into them on a regular basis without any RF
>> problems. What say you?
>>
>> Jim, K4ZMV
>> _______________________________________________
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>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>
>
> --
> martin.ewing@gmail.com
> http://blog.aa6e.net
> _______________________________________________
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>
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