One should not. I would not. I don't.
But lots of people do. Its a valid point for consideration only because it
is so common.
Now WHY it is so common is a whole other point. But I'm not going to go
there (grin).
73 de Gary, AA2IZ
----- Original Message -----
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, April 04, 2009 9:49 PM
Subject: Re: [TenTec] RF Ground
> Why would one feed a dipole, generally considered a balanced antenna, with
> an unbalanced coax? Should you do so, then you do need a RF choke at the
> feed point to reduce current on the outside of the shield. Oh there will
> always be some due to the fact the coax is in the RF field generated by
> the
> antenna and this is exacerbated by the fact that the coax feed line does
> not
> exit the antenna perpendicular for at least 1/4 wavelength.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "Gary Hoffman" <ghoffman@spacetech.com>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Saturday, April 04, 2009 5:13 PM
> Subject: Re: [TenTec] RF Ground
>
>
>>I don't feel that this is a particularly good example for the following
>> reason.
>>
>> If, and only if, the ground point at the radio where the coax is
>> terminated
>> to the radio is an excellent RF ground, then any current flowing on the
>> outside of the coax will be shunted to ground at that point. As it is an
>> excellent ground, impedance is low, and voltage will thus be low as well
>> .... ideally zero of course.
>>
>> Now I grant you that excellent RF grounds are extremely rare.
>>
>> I just don't think they are a BAD thing, in the event you are lucky
>> enough
>> to have one.
>>
>> I agree with other posters who have emphasised that lightning protection
>> must be done OUTSIDE the shack. A different issue altogether.
>>
>> I also agree with other posters who have reiterated that ALL grounds must
>> be
>> bonded together....a requirement of both Code and safety, not to mention
>> ground potential differences leading to annoying ground loops.
>>
>> As to Pin 1 problems, they exist sometimes. But remember there are many
>> additional problems out there in the world. As the seer once said....if
>> the
>> only tool you have is a hammer, every problem looks like a nail. Keep a
>> broad perspective on the potential sources of problems.
>>
>> 73 de Gary, AA2IZ
>>
>>
>> ----- Original Message -----
>> From: "Steve Hunt" <steve@karinya.net>
>> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
>> Sent: Saturday, April 04, 2009 4:13 PM
>> Subject: Re: [TenTec] RF Ground
>>
>>
>>> Have you ever considered that providing a better local RF "ground" could
>>> make "RF in the shack" problems worse?
>>>
>>> Take the example of a half-wave dipole fed with coax that is a multiple
>>> of a half-wavelength long and bonded to a "good RF ground" at the shack
>>> end. If there is no choke balun at the feedpoint, significant
>>> common-mode current will flow down the outside of the coax braid because
>>> it represents a low impedance path to earth. The better you make that
>>> "RF ground", the higher the common-mode current and the greater the
>>> potential for RF in the shack.
>>>
>>> Steve G3TXQ
>>>
>>> Martin Ewing wrote:
>>>> Yes, but... It's still worth trying to establish a local RF "ground" --
>>>> ensuring that everything in your shack is bonded together. No antenna
>>>> system is perfect, and many of us have some RF in our shacks.
>>>>
>>>
>>> _______________________________________________
>>> TenTec mailing list
>>> TenTec@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
>>>
>>
>>
>> _______________________________________________
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>>
>
>
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