I agree!
Oh, I guess it's always been done that way and somewhat or kinda works, most
of the time. And because the ARRL Handbook shows it this way.
Bob
----- Original Message -----
From: "Gary Hoffman" <ghoffman@spacetech.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, April 04, 2009 9:58 PM
Subject: Re: [TenTec] RF Ground
> 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
>>>>
>>>
>>>
>>> _______________________________________________
>>> TenTec mailing list
>>> TenTec@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
>>>
>>
>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|