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Grounding negative side of power supply?

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Don Wilhelm-4

Re: [Elecraft] Was Grounding negative side of power supply? - CORRECTING A SERIOUS ERROR

Jim,

Yes, Yes, Yes!, I think you read it wrong.

While multiple ground rods and multiple ground path are ok, National
Electric Code requires them to be connected to the Utility Entry-point
Ground. I have posted on this subject many, many times - any additional
ground rods must connect to the entry ground rod (or point) for safety
under fault conditions. I have 20 or 30 ground rods spread about for
lightning protection - all connected together by #4 or #6 wire and also
connected to the utility entry ground rod.

Yes, the neutral wire is only to be connected to the safety ground
inside the entry panel (sub-panels and wired electrical devices must
isolate the two) - but we were talking about grounds, not the neutral.

One additional note about ground rods at the service entry - I was
surprised to learn (while building a rental house this year) that now 2
ground rods are required at the entry, separated by at least 6 feet, and
connected together with a #6 or larger wire.

73,
Don W3FPR

Jim Brown wrote:

> NO, NO, NO!
>
> Joe, who rarely ever gets it wrong, has led us down a VERY wrong path,
> and you, who also rarely get it wrong, have followed him. :)
>
> It is the NEUTRAL that must be bonded to EARTH and SYSTEM GROUND at the
> main panel/service entrance, and ONLY at that panel. An additional
> NEUTRAL connection to ground (or the green wire) is what causes an unsafe
> condition.
>
> Multiple paths to earth for the chassis of equipment are a GOOD thing, as
> long as they are all bonded together. in fact, safety codes and good
> engineering practice all say that you can have as many connections to
> EARTH as you want, that more connections are better, AND that all of
> these earth connections MUST be bonded together by a low impedance path.
>
>
>

Guy, K2AV

Re: [Elecraft] Grounding negative side of power supply?

In reply to this post by Jim AB3CV

Understanding how dangerous voltages can develop on a "GROUND" wire
can sometimes be helped by understanding lightning as a very extreme
surge, a standing wave in electrons looking for some place to go to
dissipate.

The force behind the surge is is the lightning of course, and the
ground conduction as this surge spreads out is EXTREMELY lumpy,
miscellaneous, whatever you want to call it. If lightning hit a tree
in your back yard, this pulse is trying to move away from it, taking
what ever path it may to get away.

One of the paths of conduction for the surge might be from the ground
up into a ground rod to a conductor at your feedline entrance, to a
"grounding" plate, to the shield of every one of your coax feeds, to
the chassis of all your rigs. At this instance your rig cases are high
against everything else as the surge takes off down the safety ground
wire to the power ground.

Connecting the coax entry ground to the power ground with a straight
large conductor run gives the surge another EASIER way to go. Avoiding
the need for this low impedance shunt path is why a single point
ground works.

One thing that often gets missed is that a house with its foundation
system or basement can be a conduction barrier in the path of the
surge's dissipation pulse. If there is a miscellaneous conduction path
through/under the house, you want it to be a good one where detours up
to sensitive equipment is out of the way and unattractive to the
surge.

73, Guy.
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Don Wilhelm-4

Re: [Elecraft] Grounding negative side of power supply?

Guy,

That is the reason I put a perimeter wire around my house with a ground
stake every place the wire makes an abrupt turn. That wire provides any
lightning surge with a lower impedance path than that which it might
find by blowing a hole through the foundation wall.

In my opinion, definitive information on lightning protection and
station grounding was written by Ron Block, and can be found on the
PolyPhaser website - it was also published in a 2 part series in QST
some years back - it should be available to ARRL members on the ARRL
website. Those articles convinced me that the perimeter wire was the
best thing I could do.

73,
Don W3FPR

Guy Olinger K2AV wrote:

> One thing that often gets missed is that a house with its foundation
> system or basement can be a conduction barrier in the path of the
> surge's dissipation pulse. If there is a miscellaneous conduction path
> through/under the house, you want it to be a good one where detours up
> to sensitive equipment is out of the way and unattractive to the
> surge.
>
> 73, Guy.
>
>

Larry Godek

Re: [Elecraft] Grounding negative side of power supply?

Glen Zook K9STH also has good readings on grounding on his web page. They appear to be of good authority. Do a search for K9STH and it should appear.

Larry
W0OGH

-------------- Original message from Don Wilhelm <[hidden email]>: --------------

> Guy,
>
> That is the reason I put a perimeter wire around my house with a ground
> stake every place the wire makes an abrupt turn. That wire provides any
> lightning surge with a lower impedance path than that which it might
> find by blowing a hole through the foundation wall.
>
> In my opinion, definitive information on lightning protection and
> station grounding was written by Ron Block, and can be found on the
> PolyPhaser website - it was also published in a 2 part series in QST
> some years back - it should be available to ARRL members on the ARRL
> website. Those articles convinced me that the perimeter wire was the
> best thing I could do.
>
> 73,
> Don W3FPR
>
> Guy Olinger K2AV wrote:
> > One thing that often gets missed is that a house with its foundation
> > system or basement can be a conduction barrier in the path of the
> > surge's dissipation pulse. If there is a miscellaneous conduction path
> > through/under the house, you want it to be a good one where detours up
> > to sensitive equipment is out of the way and unattractive to the
> > surge.
> >
> > 73, Guy.
> >
> >
> ______________________________________________________________
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David Cutter

Re: [Elecraft] Was Grounding negative side of power supply? - CORRECTING A SERIOUS ERROR

In reply to this post by Don Wilhelm-4

A picture paints a thousand words.

Point to a web page with all this drawn and save all this bandwidth.

Someone might be then able to compare one system with another.

David
G3UNA

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Don Wilhelm-4

Re: [Elecraft] Lightning Protection articles

OK, this thread has morphed into lightning protection related topics,
and I have changed the subject line.
I checked the PolyPhaser site and the information is no longer there.

ARRL Archives has the best one I know about. It was a 3 part
publication run in June, July and August of 2002.
Author is W. Ronald Block, KB2UYT and carries the title of "Lightning
Protection for the Amateur Radio Station.
Download the 3 .PDF files - they have pictures and diagrams.

That is the guidelines I used to constructed my system. I consider this
an authoritative source, and I have not seen one since that covered all
aspects. I looked at the K9STH articles and while informative, they
lacked completeness.

73,
Don W3FPR

David Cutter wrote:
> A picture paints a thousand words.
>
>
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Joe Planisky

Re: [Elecraft] Lightning Protection articles

I think these may be the PolyPhaser articles Don was referring to.

http://www.polyphaser.com/technical_notes.aspx

73
--
Joe KB8AP

On Jan 21, 2010, at 3:56 PM, Don Wilhelm wrote:

> OK, this thread has morphed into lightning protection related topics,
> and I have changed the subject line.
> I checked the PolyPhaser site and the information is no longer there.

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Joe Planisky

Re: [Elecraft] Lightning Protection articles

In reply to this post by Don Wilhelm-4

Hi Don,

The KB2UYT articles from 2002 mentions a perimeter ring, but gives no
real details as to the construction and installation of the ring. An
article by KD7PEI in the 8/2008 QST gives more details, but still
fails to answer some questions such as:

How far away from the building foundation can the ring be? Obviously
closer means less material needed, but can it be TOO close? Can it be
too far?

How do you deal with concrete sidewalks, concrete driveways, stone
patios, or other obstacles that prevent you from placing the ring
close to the foundation? (KB2UYT does say that "A perimeter ground
that only goes three-quarters or half-way around the house is better
than no perimeter ground at all." But would it be better to get a
complete ring with parts of it 20' away from the foundation, or a
partial ring 3' away?)

Is there a recommended vertical separation between the ring conductor
and other underground pipes and wires?

If you have time and are so inclined, could you perhaps tell us more
about the ring you installed, the materials you used, and how you went
about the installation?

73
--
Joe KB8AP

On Jan 21, 2010, at 3:56 PM, Don Wilhelm wrote:

> ARRL Archives has the best one I know about. It was a 3 part
> publication run in June, July and August of 2002.
> Author is W. Ronald Block, KB2UYT and carries the title of "Lightning
> Protection for the Amateur Radio Station.
> Download the 3 .PDF files - they have pictures and diagrams.
>
> That is the guidelines I used to constructed my system. I consider
> this
> an authoritative source, and I have not seen one since that covered
> all
> aspects.

Jim Brown-10

Re: [Elecraft] Was Grounding negative side of power supply? -CORRECTING A SERIOUS ERROR

In reply to this post by Joe Subich, W4TV-4

On Thu, 21 Jan 2010 14:02:58 -0500, Joe Subich, W4TV wrote:

>While the Neutral (the white wire in the US three wire power
>cable) must be bonded to ground at the service entrance and
>nowhere else, by code the Neutral must ** NOT ** be bonded to
>the case/chassis of any equipment (e.g., white should never
>be connected to the case) so the neutral is not at issue here.

>However, the SAFETY ground (green wire/round pin) is also
>bonded to ground at the service entrance - and in most
>residential installations ONLY at that point.

That's tradition, and common practice, but there is nothing in
NEC to discourage additional earth connections to the ground
(the green wire).

>It is this situation, where the safety ground (chassis) and
>the shield of the coaxial cables (also connected to chassis)
>are at different potentials that is potentially unsafe.

No, it is bonding of neutral to the EQUIPMENT GROUND (in that
equipment) that is the problem, because it allows return current
to divide between neutral and equipment ground and any other
conductors that the equipment ground is bonded to. For example,
the return current might flow on steel building structure, or in
low voltage wiring (shields of audio or video cables, etc.), or
on metallic plumbing pipes. It makes it less likely that a fuse
will blow in the case of a fault, AND it spreads out the magnetic
field rather keeping it contained between the phase (hot) and
neutral conductors. There is a tutorial drawing of this in the
Ham Interfacing tutorial, and also in the Power and Grounding
tutorial.

The connection of power system ground wiring (the equipment
ground, also called the green wire) to earth at multiple points
is highly desirable. As you noted, it helps all the wiring "rise
and fall together" in the event of a lightning event, thus
minimizing the voltage between interconnected equipment.

That is, of course, a double edged sword, since currents will be
induced in loops by magnetic coupling, but authorities agree that
having the building rise and fall together is far more of a
factor than induced current.

73,

Jim Brown K9YC

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Don Wilhelm-4

Re: [Elecraft] Lightning Protection articles

In reply to this post by Joe Planisky

Joe,

Details on *my* perimeter ring -- I put mine in while backfilling around
the foundation, used #4 wire and placed it 6 to 12 inches under the
final grade. It is located quite near the foundation - from zero to 12
inches. There is a driven 8 ft. ground rod at every corner and any
other place where the wire must make a turn - in my case, that is 9
ground rods. Rather than CAD-welding and burying the ends of the rods
and wire, I choose to clamp mine using clamps above the ground, so at
each ground rod location, the wire comes upward in a smooth arc to clamp
above the ground. I can go around the house and check each clamp each
spring and fall - just try to snug it down a bit with a wrench, if it
moves it needed tightening. That takes only a short time for that
maintenance. Every conductor exiting the building is tied to this
perimeter wire, but in my case there are none other than the utilities -
electric and telephone - all plumbing is PVC or CPVC.

There is nothing wrong with a perimeter wire further away from the
foundation, that is just the way I did it. I had no sidewalks to
contend with because they had not yet been built. Each installation
will be different, and the installer may have to be creative.
If I had sidewalks or paved driveways to deal with, I would look at
methods like running the wire through an expansion joint area, or boring
through under the concrete. I believe the continuity is more important
than the depth of the wire, but that is just my guess, I have no data.

As pointed out in the QST articles - do the best you can and know the
shortcomings of your installation. That knowledge *should* be able to
tell you how much you can trust it during a lightning event and how far
you should stay away from the equipment during a lightning event.
Unless you have an installation using much larger conductors than I have
used, and bring all conductors into the operating area through a single
"grounding window", then do not even think about operating through a
lightning storm as commercial broadcast stations do. If I had 00 wire
for the perimeter wire and the ground connections and a continuous sheet
of copper under the floor to keep everything at the same potential, I
might consider operating through a storm, but I do not have that kind of
installation - I just believe mine is better than many.

The answer to part of what started this discussion is still unchanged,
all ground rods should be connected to the utility entry ground - that
is a part of the AC grounding scheme and is to keep all persons safe in
case of an electrical fault. Lightning protection is a different
animal, but in the case where we hams tend to drive additional ground
rods, the two can be (but not necessarily) considered together. Neither
of these grounding systems should be considered as an RF ground - that
is another subject entirely.

73,
Don W3FPR

Joe Planisky wrote:

> Hi Don,
>
> The KB2UYT articles from 2002 mentions a perimeter ring, but gives no
> real details as to the construction and installation of the ring. An
> article by KD7PEI in the 8/2008 QST gives more details, but still
> fails to answer some questions such as:
>
> How far away from the building foundation can the ring be? Obviously
> closer means less material needed, but can it be TOO close? Can it be
> too far?
>
> How do you deal with concrete sidewalks, concrete driveways, stone
> patios, or other obstacles that prevent you from placing the ring
> close to the foundation? (KB2UYT does say that "A perimeter ground
> that only goes three-quarters or half-way around the house is better
> than no perimeter ground at all." But would it be better to get a
> complete ring with parts of it 20' away from the foundation, or a
> partial ring 3' away?)
>
> Is there a recommended vertical separation between the ring conductor
> and other underground pipes and wires?
>
> If you have time and are so inclined, could you perhaps tell us more
> about the ring you installed, the materials you used, and how you went
> about the installation?
>
>

P.B. Christensen

Re: [Elecraft] Was Grounding negative side of power supply?-CORRECTING A SERIOUS ERROR

In reply to this post by Jim Brown-10

> That's tradition, and common practice, but there is nothing in
> NEC to discourage additional earth connections to the ground
> (the green wire).

Supplemental electrode grounding is allowed under NEC Article 250.54. One
exception to multiple ground points on a circuit is the use of an isolated
ground (IG) where a receptacle's dedicated ground lead is brought back
directly to an upstream ground point (typically the serving main or sub
panel) and does not come in electrical contact with conduit or other premise
ground wiring between the receptacle and the isolated ground point.

Unlike standard receptacles, IG outlets break the continuity between the
receptacle's ground screw and the metallic mounting yoke. But, IG circuits
are often more trouble than they're worth since the isolated ground used to
protect sensitive equipment is often undermined by alternate grounding paths
from other grounded sources through inter-connected cabling.

Paul, W9AC

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Joe Subich, W4TV-4

Re: [Elecraft] Was Grounding negative side of power supply?-CORRECTING A SERIOUS ERROR

In reply to this post by Jim Brown-10

Jim,

> No, it is bonding of neutral to the EQUIPMENT GROUND (in that
> equipment) that is the problem, because it allows return current
> to divide between neutral and equipment ground and any other
> conductors that the equipment ground is bonded to.

Bonding the neutral to the equipment ground (chassis) in the
equipment is a violation of both NEC and UL standards. Both
power conductors (hot/black and neutral/white) must be isolated
from the chassis/equipment ground.

Per NEC, the neutral should be grounded exactly one place -
at the power entrance. Connecting neutral to the chassis,
and via the chassis to the safety ground, would violate NEC.
In addition connecting neutral to the equipment chassis could
(would?) result in improper operation of any GFCI on that
circuit.

The issue of multiple grounding is entirely separate from
"grounding the neutral."

73,

... Joe, W4TV

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Jim Brown
> Sent: Friday, January 22, 2010 3:15 AM
> To: Elecraft List
> Subject: Re: [Elecraft] Was Grounding negative side of power
> supply?-CORRECTING A SERIOUS ERROR
>
>
> On Thu, 21 Jan 2010 14:02:58 -0500, Joe Subich, W4TV wrote:
>
> >While the Neutral (the white wire in the US three wire power
> >cable) must be bonded to ground at the service entrance and
> >nowhere else, by code the Neutral must ** NOT ** be bonded to
> >the case/chassis of any equipment (e.g., white should never
> >be connected to the case) so the neutral is not at issue here.
>
> >However, the SAFETY ground (green wire/round pin) is also
> >bonded to ground at the service entrance - and in most
> >residential installations ONLY at that point.
>
> That's tradition, and common practice, but there is nothing in
> NEC to discourage additional earth connections to the ground
> (the green wire).
>
> >It is this situation, where the safety ground (chassis) and
> >the shield of the coaxial cables (also connected to chassis)
> >are at different potentials that is potentially unsafe.
>
> No, it is bonding of neutral to the EQUIPMENT GROUND (in that
> equipment) that is the problem, because it allows return current
> to divide between neutral and equipment ground and any other
> conductors that the equipment ground is bonded to. For example,
> the return current might flow on steel building structure, or in
> low voltage wiring (shields of audio or video cables, etc.), or
> on metallic plumbing pipes. It makes it less likely that a fuse
> will blow in the case of a fault, AND it spreads out the magnetic
> field rather keeping it contained between the phase (hot) and
> neutral conductors. There is a tutorial drawing of this in the
> Ham Interfacing tutorial, and also in the Power and Grounding
> tutorial.
>
> The connection of power system ground wiring (the equipment
> ground, also called the green wire) to earth at multiple points
> is highly desirable. As you noted, it helps all the wiring "rise
> and fall together" in the event of a lightning event, thus
> minimizing the voltage between interconnected equipment.
>
> That is, of course, a double edged sword, since currents will be
> induced in loops by magnetic coupling, but authorities agree that
> having the building rise and fall together is far more of a
> factor than induced current.
>
> 73,
>
> Jim Brown K9YC
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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alorona

Re: [Elecraft] Grounding negative side of power supply?

In reply to this post by Don Wilhelm-4

Variations on this thread surface every few months but for a thickhead like me the essential idea seems to finally be sinking in.

If I can ask you guys to simplify and reiterate, what you are saying is that for an arrangement where the shack is in a separate building that is 75 feet from the electrical service entrance/ground rod and is served by its own 240 VAC circuit, the green wire as it enters the shack should be connected to the RF ground rod just outside the shack? That this is not only allowable but desirable, correct?

I still have trouble understanding how two ground points connected by 75 or 100 feet of #10 wire can maintain the same potential if any current flows in that wire, but I guess it's better than not having them connected, is that the right idea?

Al W6LX
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Eric Swartz - WA6HHQ

Re: [Elecraft] Was Grounding negative side of power supply?-CORRECTING A SERIOUS ERROR [END of Thread]

Administrator

In reply to this post by Joe Subich, W4TV-4

Guys - Time to end this thread (and related grounding, lightening
threads). Please take it off list and correspond directly with one
another. If you all are able to come to an agreement, then feel free to
post a summary of the results.

73, Eric WA6HHQ
Elecraft Moderator
----

>
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David Cutter

Re: [Elecraft] Was Grounding negative side of power supply?-CORRECTING A SERIOUS ERROR [END of Thread]

Eric

I suggested that a picture is worth a 1000 words and here is a leaflet from
the RSGB which explains some of the subject for UK amateurs. I'm sure
there's a similar leaflet from ARRL and other societies.

http://www.rsgb.org/emc/pdfs/leaflets/emc_leaflet07.pdf

73
David
G3UNA

> Guys - Time to end this thread (and related grounding, lightening
> threads). Please take it off list and correspond directly with one
> another. If you all are able to come to an agreement, then feel free to
> post a summary of the results.
>
> 73, Eric WA6HHQ
> Elecraft Moderator
> ----
>
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Bill Coleman-2

Re: Grounding negative side of power supply?

In reply to this post by rlindzen

On Jan 20, 2010, at 11:47 PM, Richard S. Lindzen wrote:

> Dear Don,
>
> This leaves me a bit concerned. I am planning to put up a K9AY
> receiving antenna in my backyard and it is supposed to be connected
> to a ground rod. I had never seen it suggested that this must be
> connected to the utility ground stake. I'm not even sure where the
> utility ground stake is. I've never noticed one though I will ask my
> electrician. If there is one, it is likely to be pretty far from the K9AY.

For the K9AY, your best bet is to make sure the antenna ground and the coax ground are completely isolated. I do this by magnetically coupling the coax with a 9:1 transformer. Otherwise, common-mode noise can move out the shield and be picked up by the antenna.

Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901

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Bob McGraw - K4TAX

Re: Grounding negative side of power supply?

Yes, do provide a driven ground for the K9AY receiving antenna. This is
required for lightning protection. AND be sure to bond this ground to
the AC mains ground for the house. Failure to do this will produce a
voltage difference or step voltage between the two ground during a nearby
lightning strike. The voltage difference can be enough to damage or
destroy the radio connected between the antenna and the AC power. AND,
bonding of all grounds to a common point is a requirement of the NEC.

Remember, lighting has traveled through several thousand feet of air. A
balun will offer little to no protection in this regard. Now placing a
choke balun or a 1:1 current balun at the feed point will reduce common
mode noise on the coax feed line.

73
Bob, K4TAX

>
> On Jan 20, 2010, at 11:47 PM, Richard S. Lindzen wrote:
>
>> Dear Don,
>>
>> This leaves me a bit concerned. I am planning to put up a K9AY
>> receiving antenna in my backyard and it is supposed to be connected
>> to a ground rod. I had never seen it suggested that this must be
>> connected to the utility ground stake. I'm not even sure where the
>> utility ground stake is. I've never noticed one though I will ask my
>> electrician. If there is one, it is likely to be pretty far from the
>> K9AY.
>
> For the K9AY, your best bet is to make sure the antenna ground and the
> coax ground are completely isolated. I do this by magnetically coupling
> the coax with a 9:1 transformer. Otherwise, common-mode noise can move
> out the shield and be picked up by the antenna.
>
> Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
> Web: http://boringhamradiopart.blogspot.com
> Quote: "Not within a thousand years will man ever fly!"
> -- Wilbur Wright, 1901
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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W8JI

Re: Grounding negative side of power supply?

This appears to be a question from January 20, 2010, so it
is a little late, but a person never wants to connect the
ground rod of the K9AY antenna or any other small or low
receiving antenna to the mains ground.

First, it would kill the advantage of having the antenna. If
you are going to do that, don't bother installing the
antenna. It will hurt the antenna in more than one way.

Second, it is not necessary for safety. It is not a large
tall structure and is not likely at all to be involved with
a direct lightning hit, and even if it were hit the ground
at the cable entrance to the house would provide all the
required protection.

The shack ground and the antenna entrance ground should be
bonded to the mains, but the K9AY or any other low noise
receiving array must have an isolated ground. The cable
leaving the receiving antenna should be buried, should have
common mode isolation, and should be grounded at the house
entrance to a ground that is bonded to the mains ground.

73 Tom

----- Original Message -----
From: "Robert Mcgraw" <[hidden email]>
To: "Bill Coleman" <[hidden email]>
Cc: <[hidden email]>; <[hidden email]>
Sent: Sunday, April 18, 2010 10:35 PM
Subject: Re: [Elecraft] Grounding negative side of power
supply?

Yes, do provide a driven ground for the K9AY receiving
antenna. This is
required for lightning protection. AND be sure to bond this
ground to
the AC mains ground for the house. Failure to do this will
produce a
voltage difference or step voltage between the two ground
during a nearby
lightning strike. The voltage difference can be enough to
damage or
destroy the radio connected between the antenna and the AC
power. AND,
bonding of all grounds to a common point is a requirement of
the NEC.

Remember, lighting has traveled through several thousand
feet of air. A
balun will offer little to no protection in this regard.
Now placing a
choke balun or a 1:1 current balun at the feed point will
reduce common
mode noise on the coax feed line.

73
Bob, K4TAX

>
> On Jan 20, 2010, at 11:47 PM, Richard S. Lindzen wrote:
>
>> Dear Don,
>>
>> This leaves me a bit concerned. I am planning to put up
>> a K9AY
>> receiving antenna in my backyard and it is supposed to be
>> connected
>> to a ground rod. I had never seen it suggested that this
>> must be
>> connected to the utility ground stake. I'm not even sure
>> where the
>> utility ground stake is. I've never noticed one though I
>> will ask my
>> electrician. If there is one, it is likely to be pretty
>> far from the
>> K9AY.
>
> For the K9AY, your best bet is to make sure the antenna
> ground and the
> coax ground are completely isolated. I do this by
> magnetically coupling
> the coax with a 9:1 transformer. Otherwise, common-mode
> noise can move
> out the shield and be picked up by the antenna.
>
> Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
> Web: http://boringhamradiopart.blogspot.com
> Quote: "Not within a thousand years will man ever fly!"
> -- Wilbur Wright, 1901
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: A known bad url was replaced by VIPRE
> Please help support this email list: A known bad url was
> replaced by VIPRE
>

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alsopb

Re: Grounding negative side of power supply?

I did a calculation of how many feet of heavy gauge wire would be
required to do this grounding.
Glad it isn't necessary.
For some stations one would be talking thousands of feet of wire to tie
all the RX antenna grounds to the mains ground.
One wants to keep the RX antennas well away from TX antennas

The cost of the wire would greatly exceed the cost of the equipment one
is trying to protect..
It seems highly unlikely such lengths would keep all grounds at equal
potential for a nearby lightning strike transient anyhow.

73 de Brian/K3KO

Tom W8JI wrote:

>This appears to be a question from January 20, 2010, so it
>is a little late, but a person never wants to connect the
>ground rod of the K9AY antenna or any other small or low
>receiving antenna to the mains ground.
>
>First, it would kill the advantage of having the antenna. If
>you are going to do that, don't bother installing the
>antenna. It will hurt the antenna in more than one way.
>
>Second, it is not necessary for safety. It is not a large
>tall structure and is not likely at all to be involved with
>a direct lightning hit, and even if it were hit the ground
>at the cable entrance to the house would provide all the
>required protection.
>
>The shack ground and the antenna entrance ground should be
>bonded to the mains, but the K9AY or any other low noise
>receiving array must have an isolated ground. The cable
>leaving the receiving antenna should be buried, should have
>common mode isolation, and should be grounded at the house
>entrance to a ground that is bonded to the mains ground.
>
>73 Tom
>
>
>----- Original Message -----
>From: "Robert Mcgraw" <[hidden email]>
>To: "Bill Coleman" <[hidden email]>
>Cc: <[hidden email]>; <[hidden email]>
>Sent: Sunday, April 18, 2010 10:35 PM
>Subject: Re: [Elecraft] Grounding negative side of power
>supply?
>
>
>Yes, do provide a driven ground for the K9AY receiving
>antenna. This is
>required for lightning protection. AND be sure to bond this
>ground to
>the AC mains ground for the house. Failure to do this will
>produce a
>voltage difference or step voltage between the two ground
>during a nearby
>lightning strike. The voltage difference can be enough to
>damage or
>destroy the radio connected between the antenna and the AC
>power. AND,
>bonding of all grounds to a common point is a requirement of
>the NEC.
>
>Remember, lighting has traveled through several thousand
>feet of air. A
>balun will offer little to no protection in this regard.
>Now placing a
>choke balun or a 1:1 current balun at the feed point will
>reduce common
>mode noise on the coax feed line.
>
>73
>Bob, K4TAX
>
>
>
>
>
>>On Jan 20, 2010, at 11:47 PM, Richard S. Lindzen wrote:
>>
>>
>>
>>>Dear Don,
>>>
>>>This leaves me a bit concerned. I am planning to put up
>>>a K9AY
>>>receiving antenna in my backyard and it is supposed to be
>>>connected
>>>to a ground rod. I had never seen it suggested that this
>>>must be
>>>connected to the utility ground stake. I'm not even sure
>>>where the
>>>utility ground stake is. I've never noticed one though I
>>>will ask my
>>>electrician. If there is one, it is likely to be pretty
>>>far from the
>>>K9AY.
>>>
>>>
>>For the K9AY, your best bet is to make sure the antenna
>>ground and the
>>coax ground are completely isolated. I do this by
>>magnetically coupling
>>the coax with a 9:1 transformer. Otherwise, common-mode
>>noise can move
>>out the shield and be picked up by the antenna.
>>
>>Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
>>Web: http://boringhamradiopart.blogspot.com
>>Quote: "Not within a thousand years will man ever fly!"
>> -- Wilbur Wright, 1901
>>
>>______________________________________________________________
>>Elecraft mailing list
>>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>Help: http://mailman.qth.net/mmfaq.htm
>>Post: mailto:[hidden email]
>>
>>This list hosted by: A known bad url was replaced by VIPRE
>>Please help support this email list: A known bad url was
>>replaced by VIPRE
>>
>>
>>
>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: A known bad url was replaced by VIPRE
>Please help support this email list: A known bad url was
>replaced by VIPRE
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
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>Please help support this email list: http://www.qsl.net/donate.html
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>
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>

Bob McGraw - K4TAX

Re: Grounding negative side of power supply?

In reply to this post by W8JI

To Tom, Bill and all:

I never said anything about a "direct" strike. Don't bother trying to
protect for a direct strike. Nothing will survive a direct strike.

The problem is two ground points, separated by some distance of earth be it
5 ft, 50 ft or 500 ft. During a nearby strike the energy from the nearby
strike is dissipated largely across the surface of the earth up to a depth
of some 18" to 24". Due to resistance between the two ground points and the
energy flowing through the earth there will be a difference in potential
between the two points. Now, with the radio connected between the receiving
antenna and the AC mains, the path for the current difference is through the
radio and power supply.

It's your radio, it's your choice. You decide.

73
Bob, K4TAX

----- Original Message -----
From: "Tom W8JI" <[hidden email]>
To: <[hidden email]>; "Bill Coleman" <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, April 19, 2010 12:03 AM
Subject: Re: [Elecraft] Grounding negative side of power supply?

> This appears to be a question from January 20, 2010, so it
> is a little late, but a person never wants to connect the
> ground rod of the K9AY antenna or any other small or low
> receiving antenna to the mains ground.
>
> First, it would kill the advantage of having the antenna. If
> you are going to do that, don't bother installing the
> antenna. It will hurt the antenna in more than one way.
>
> Second, it is not necessary for safety. It is not a large
> tall structure and is not likely at all to be involved with
> a direct lightning hit, and even if it were hit the ground
> at the cable entrance to the house would provide all the
> required protection.
>
> The shack ground and the antenna entrance ground should be
> bonded to the mains, but the K9AY or any other low noise
> receiving array must have an isolated ground. The cable
> leaving the receiving antenna should be buried, should have
> common mode isolation, and should be grounded at the house
> entrance to a ground that is bonded to the mains ground.
>
> 73 Tom
>
>
> ----- Original Message -----
> From: "Robert Mcgraw" <[hidden email]>
> To: "Bill Coleman" <[hidden email]>
> Cc: <[hidden email]>; <[hidden email]>
> Sent: Sunday, April 18, 2010 10:35 PM
> Subject: Re: [Elecraft] Grounding negative side of power
> supply?
>
>
> Yes, do provide a driven ground for the K9AY receiving
> antenna. This is
> required for lightning protection. AND be sure to bond this
> ground to
> the AC mains ground for the house. Failure to do this will
> produce a
> voltage difference or step voltage between the two ground
> during a nearby
> lightning strike. The voltage difference can be enough to
> damage or
> destroy the radio connected between the antenna and the AC
> power. AND,
> bonding of all grounds to a common point is a requirement of
> the NEC.
>
> Remember, lighting has traveled through several thousand
> feet of air. A
> balun will offer little to no protection in this regard.
> Now placing a
> choke balun or a 1:1 current balun at the feed point will
> reduce common
> mode noise on the coax feed line.
>
> 73
> Bob, K4TAX
>
>
>
>>
>> On Jan 20, 2010, at 11:47 PM, Richard S. Lindzen wrote:
>>
>>> Dear Don,
>>>
>>> This leaves me a bit concerned. I am planning to put up
>>> a K9AY
>>> receiving antenna in my backyard and it is supposed to be
>>> connected
>>> to a ground rod. I had never seen it suggested that this
>>> must be
>>> connected to the utility ground stake. I'm not even sure
>>> where the
>>> utility ground stake is. I've never noticed one though I
>>> will ask my
>>> electrician. If there is one, it is likely to be pretty
>>> far from the
>>> K9AY.
>>
>> For the K9AY, your best bet is to make sure the antenna
>> ground and the
>> coax ground are completely isolated. I do this by
>> magnetically coupling
>> the coax with a 9:1 transformer. Otherwise, common-mode
>> noise can move
>> out the shield and be picked up by the antenna.
>>
>> Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
>> Web: http://boringhamradiopart.blogspot.com
>> Quote: "Not within a thousand years will man ever fly!"
>> -- Wilbur Wright, 1901
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: A known bad url was replaced by VIPRE
>> Please help support this email list: A known bad url was
>> replaced by VIPRE
>>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: A known bad url was replaced by VIPRE
> Please help support this email list: A known bad url was
> replaced by VIPRE
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

123