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Re: [TenTec] RF Ground

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] RF Ground
From: "Gary Hoffman" <ghoffman@spacetech.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 5 Apr 2009 18:46:15 -0400
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Ok Jim,

I quit.  Its a nail.

73 de Gary, AA2IZ

----- Original Message ----- 
From: "Jim Brown" <k9yc@audiosystemsgroup.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Sunday, April 05, 2009 3:01 PM
Subject: Re: [TenTec] RF Ground

> Gary Hoffman wrote:
>> My point is different.
>> I don't care if the coax radiates.  In fact I accept that it will in
>> virtually all cases, at least to a degree.
> I do, for three reasons. RF in the shack, RF in my living room and my
> neighbor's living room, and, VERY important, noise coupled from
> reception on the coax to the antenna to the RX.
>> I was referring to the effect at the input to the radio.
> IF the coax is connected to the CHASSIS of the radio, no shield current
> (common mode) enters the radio. If, however, the shield is connected to
> some point INSIDE the radio (by definition, a pin 1 problem), shield
> current (common mode current) WILL enter the radio.
>> If we shunt the current away from the radio....to ground... at that 
>> point,
>> then it will not flow into the radio.
> This doesn't matter if there's no pin 1 problem (that is, if the shield
> goes straight to the chassis).
>> I was trying to keep noise out of the radio, for the purposes of 
>> addressing
>> the original "buzz" problem.
>> Of course many posters here don't agree that ground has anything to do 
>> with
>> it, and some focus on "pin 1" and others have their pet causes.  I was
>> addressing one item that had a theoretical solution.
> I'm simply cutting straight to the physics of what's happening. As EMC
> guru Henry Ott says, we must keep track of where the current is flowing.
> Henry talks about the hidden schematic concealed behind the "ground"
> symbol. As Bob, K4TAX, observes, those points labeled "ground" are not a
> single point, they are wires with inductance and resistance. If current
> flows on them, they will radiate. Any radio wave that hits it will
> induce voltage and current. And any current will produce an IZ drop.
> If you guys went to study my tutorials on the pin 1 problem, you
> wouldn't be arguing with me!  :)
> 73,
> Jim Brown K9YC
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