Re: Station Grounding


Bry Carling <af4k@...>
 

Don - It's not me you are disagreeing but with ARRL. I copied and pasted. Take your semantics up with them.


If you want to get RF burns and feedback in your shack you are welcome to.



From: Don Wilhelm
Sent: Monday, January 30, 2017 11:51 PM
To: Bry Carling; 4sqrp@...
Subject: Re: [4sqrp] Station Grounding
 
Bry,

I must strongly disagree.
An RF Ground must have a low impedance at all frequencies in the RF
spectrum.
Consider my example of an 8 foot wire (or braid or whatever conductor)
to a ground rod.
Yes, the impedance at the ground rod is low, but the 28MHz impedance at
the end of an 8 foot conductor is quite high.  As such it will be very
ineffective as a low impedance path to ground.
It is plain physics - a 1/4 wavelength of wire having a low impedance at
one end will have a high impedance at the other end.
What is the electrical length of the conductor to your ground rod?  No
matter what the length, it will be a quarter wavelength at some frequency.

If you want to create a low impedance RF ground path, use a wire that is
1/4 wavelength long and leave the far end open - in other words a
"counterpoise wire" - it will have a low impedance at the shack end, no
ground rod required.

Read the ARRL article you quoted carefully, for RF ground, it refers to
radials at the base of an antenna, not a ground rod - except for a 1/2
wavelength radiator.

73,
Don W3FPR

On 1/30/2017 10:44 PM, Bry Carling wrote:
> >>There is no way that a ground rod will create an RF Ground for your
> station.
>
> Sorry to have to say it Don but, you are mistaken
>
>
> The first thing to know is that there are three functions served by
> grounding in ham shacks: 1. Electrical Safety 2. Stray RF Suppression
> (or simply RF Grounding) 3. Lightning Protection. Each has it's own
> set of requirements, but not all station setups need every kind of ground.
>
>
> You can say it all you want. I have seen RFI problems come about in my
> shack when a ground wire accidentally came off a rig. I have even had
> RF burns off a Drake TR4 when the ground became disconnected. Don;t
> kid yourself tat a ground is not needed for RF reasons.
>
>
> If an AC safety was the only reason for grounding equipment then the
> manufacturers would be satisfied with the 3rd wire ground providing a
> suitable ground for all amateur radio equipment. The reality is this: 
> I don't know of ANY reputable manufacturer that does not provide a
> separate terminal for that braid or green wire to go to the ground rod
> outside. There is a good reason for that!
>
>
> I have been a radio amateur for 48 years and I know what I am talking
> about. I was an SWL for a few years before that and we had a buried
> chassis with coal and salt on it in the back garden  for lack of a
> costly ground rod.
>
>
> You can learn more here:
>
>
> http://www.arrl.org/grounding
www.arrl.org
After antennas, station grounding is probably the most discussed subject in amateur radio and it is also the one replete with the most misconceptions.

>
> Grounding - American Radio Relay League <http://www.arrl.org/grounding>
www.arrl.org
After antennas, station grounding is probably the most discussed subject in amateur radio and it is also the one replete with the most misconceptions.

> www.arrl.org
www.arrl.org
The American Radio Relay League (ARRL) is the national association for amateur radio, connecting hams around the U.S. with news, information and resources.

> After antennas, station grounding is probably the most discussed
> subject in amateur radio and it is also the one replete with the most
> misconceptions.
>
>
>
>
> ------------------------------------------------------------------------
> *From:* 4sqrp@... <4sqrp@...> on behalf of Don
> Wilhelm donwilh@... [4sqrp] <4sqrp@...>
> *Sent:* Monday, January 30, 2017 9:09 PM
> *To:* 4sQRP Yahoo Reflector
> *Subject:* Re: [4sqrp] Station Grounding
>
> There is no way that a ground rod will create an RF Ground for your
> station. The earth is not a 'sink' for RF energy. The ground for your
> station is for AC safety and lightning protection only.
> Your station ground rod must be connected to the AC mains entry ground
> rod by a #6 or larger wire - that is for the safety of you and your
> household as well as being a NEC requirement. The only exception is if
> the ground rods are 100 feet or more apart.
>
> For curing "RF in the shack", look to your antenna system and use means
> to keep the RF off the antenna feedlines. Balanced antennas help, and
> running your feedline at right angles to the antenna for at least 1/4
> wavelength will help a lot, and any antenna should have an effective
> common mode choke (some baluns qualify, others are poor) at the antenna
> feedpoint will keep common mode RF off the feedline.
>
> Even at QRP levels, RF-in-the-shack can cause "strange happenings". A
> ground rod will not cure that problem.
>
> Consider an 8 foot connection to a ground rod - at 28MHz the end of that
> grounding point will have a high impedance to 28 MHz RF - for an RF
> Ground, a very low impedance is needed, so any length of wire to the
> ground will not be effective for RF - in fact, it will do quite the
> opposite.
>
> Bottom line - do not rely on a ground rod for an RF ground - it just
> will not be.
>
> 73,
> Don W3FPR
>
> Sun Jan 29, 2017 8:10 pm (PST) . Posted by:
> "Tim McDonough N9PUZ" tim_n9puz
> Most books and articles you read on creating a good RF ground for your
> station rely on you having a very short run of cable from the common
> ground at your operating location to the ground rod that's just outside
> the basement wall or ground floor window of your shack. This is good
> advice but my ham shack locations never seem to occupy a space near this
> ideal ground rod. They are in an upstairs bedroom or the most difficult
> corner of the basement possible.
>
> The following article by Tim Ellison at Flex Radio Systems discusses all
> of those "easy" situations plus offers some solutions for when that
> ground point is a story or so above ground or 30 feet or more from your
> only accessible ground point.
>
> <https://helpdesk.flexradio.com/hc/en-us/articles/204779159-Grounding-Systems-in-the-Ham-Shack-Paradigms-Facts-and-Fallacies>
helpdesk.flexradio.com
Content provided by: Jose I. Calderon, DU1ANV - Makiling Amateur Radio Society. Member: Philippine Amateur Radio Association (PARA). Reprinted with permission of the ...

>
> Tim N9PUZ
>
>

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