Re: Station Grounding


Bry Carling <af4k@...>
 

>>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.




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.



Tim N9PUZ

Join main@4SQRP.groups.io to automatically receive all group messages.