Here is a schematic of my grounding. Now, not everyone can do this. I was
fortunate to be able to get it done during a phase of reconstruction after
getting hammered by a hurricane in 2011. If the attachment is truncated,
you can view it on my qrz page. Grounding is so important!
Anthony
On Thu, Jan 23, 2025, 15:29 Michael Carter via RFI <rfi@contesting.com>
wrote:
> Dale, your comments are the single best affirmation of the importance of
> proper bonding and grounding I've seen in any forum I read. The fact that
> you are a seasoned EMC professional, as is W0LEV, speaks volumes.
>
> Thanks for relating your direct experiences with lightning's awesome
> destructive potential (no pun intended).
>
> 73,
> Mike, K8CN
> ________________________________
> From: RFI <rfi-bounces+mike.carter=unh.edu@contesting.com> on behalf of
> Dale <svetanoff@earthlink.net>
> Sent: Wednesday, January 22, 2025 9:59 PM
> To: David Eckhardt <davearea51a@gmail.com>; jim@audiosystemsgroup.com <
> jim@audiosystemsgroup.com>
> Cc: rfi@contesting.com <rfi@contesting.com>
> Subject: Re: [RFI] Common Mode Noise?
>
> CAUTION: This email originated from outside of the University System. Do
> not click links or open attachments unless you recognize the sender and
> know the content is safe.
>
>
> Dave,
>
> My comments are addressed to the following part of your post:
>
> Further, I have never, except for the first three or so years I was
> licensed, "grounded"
> (earthed) my station. Three kinds of earth connection: 1) safety (the
> "green" wire), 2) ESD bleed dump, and 3) lightning remediation (not direct
> strikes, but for radiated fields from near-by strikes). Also, realize the
> typical amateur budget does not allow for protection against direct
> strikes!
>
> - - - - - - - -
>
> The description of your earthing configuration sounds very typical to that
> of most hams I have spoken with on the subject. (Note: I was also a
> reviewer and contributor to the ARRL book on grounding and bonding.) I
> have to agree with you about the cost of doing a complete grounding and
> lightning protection scheme for any station having more than a very few
> transmission lines. I designed my installation back in 2001, using
> MIL-HDBK-419A as my guide (I am retired from Rockwell Collins as an EMC
> engineer). I have around a dozen coaxial cables, plus rotator and remote
> switching lines, each of which is lightning protected. Yes, I could have
> purchased a decent transceiver for the funds expended to do all of that.
>
> In my case, there has been a big payoff for all of that effort: on June 8,
> 2008, my 100 foot tower (home to my VHF and UHF arrays) took a direct
> lightning strike while I was using the antennas to handle emcomms related
> to severe T-storms in the area. All of the equipment in the shack and,
> most importantly, ME, survived the hit. (I was actually transmitting on 2m
> when the strike hit. I was a victim of "near strike lightning" because the
> shack is about 50 feet from the tower, which was conducting about 60kA
> [estimated by a Collins colleague who was the high energy physics expert].
> The coupled field did produce a charge in my body; the charge discharged
> from my right arm to the metal cabinet of the Astron power supply.)
>
> The same tower took another hit in May, 2009. I was not transmitting at
> that time, but all equipment in the shack and house escaped damage. I
> attribute the lack of damage to the bonding of the RF system grounds to the
> house electrical ground, thus eliminating the huge electrical difference
> between the two grounding systems. Of course, antennas, coax cables, and
> other items mounted on the tower were damaged in both strikes, but zero
> damage inside the house and shack. Two of the coaxial line protectors were
> blown apart.
>
> I'll conclude by saying that extensive grounding and lightning protection
> does work, but cost is the big factor. Hams living in areas of high
> lightning activity should, at the very least, consider observing proper
> grounding and bonding techniques. If buying enough protectors is not
> economically feasible, then thought should be given to disconnecting of
> cables when the station is not in use.
>
> 73, Dale
> WA9ENA
>
>
> -----Original Message-----
> From: David Eckhardt <davearea51a@gmail.com>
> Sent: Jan 22, 2025 3:54 PM
> To: <jim@audiosystemsgroup.com>
> Cc: <rfi@contesting.com>
> Subject: Re: [RFI] Common Mode Noise?
>
> Jim, far too many hams solidly believe open wire, parallel conductor XMSN
> lines, radiates just because it isn't shielded. Absolutely wrong if care
> is taken to keep the currents balanced and the phases opposite. They simply
> do not understand nor want to take the time to understand the rank basics
> of a transmission line, coax or open wire, or for that matter, G-line.
>
> Nor do they understand that ANY amateur antenna like a dipole is
> UNBALANCED. Period! Even Uncle most times can not assure that. As you
> commented, the local environment dictates unbalance between the two sides
> of a dipole, unless it's in free space..... How many of us absolutely
> assure homogeneity for a couple of lambda below our antennas? I'll bet
> none of us hams do, myself included. But I know how to build, measure, and
> install common mode chokes and use them intelligently.
>
> When Uncle installed the ported coax around the fissile material storage
> facility on Kirtland AFB in Albuquerque, N.M., he spent millions and
> millions of your and my tax dollars in preparing the surrounding soil.
> Even then it wasn't perfect and quite problematic.
>
> Yes, I use parallel conductor XMSN line for my HF wires (doublet),
> exclusively, except for my vertical which is by design, unbalanced. Hams
> don't get that, either! How many times have I read the question on a
> number of sites, "Do I need a balun or common mode choke on my vertical"?
> DDaaaaahhhhh......
>
> Dave - WØLEV
>
> On Wed, Jan 22, 2025 at 7:35 PM Jim Brown wrote:
>
> > On 1/22/2025 10:43 AM, K9MA wrote:
> > > The whole point of using coax is to prevent radiation until the RF gets
> > > to the antenna. There's no need to further complicate the issue.
> >
> > There is no more or less radiation from a 2-wire line than from coax.
> > What causes radiation is common mode current, and 2-wire can carry just
> > as much common mode as coax of the total antenna system is unbalanced.
> > Just as in coax, common mode current in 2-wire line shows up as a
> > difference between current in the two wires, taking both magnitude and
> > phase into account.
> >
> > Antennas can be unbalanced by their surroundings, like variable height,
> > sloping ground, nearby conductive objects, imbalance in the termination
> > of 2-wire line in the shack, including a poorly balanced tuner or
> > matching network.
> >
> > 73, Jim K9YC
> >
> > _______________________________________________
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> > RFI@contesting.com
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> --
>
> *Dave - WØLEV*
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