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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