i have a question.

in reference to station grounding, i have read keep the grounding strap
as short as possible and not a multiple of a resonant length on the ham
bands. with that in mind, even if i ground pieces of equipment to individual
ground rods, won't the complete grounding system be long? in my mind i am
looking around the room and seeing a grounding system being at least 12 feet
long, if i go along the perimeter of the desks (which are in a "U" shape in
the room.

trying to grasp this in a practical sense. sorry if it is basic and i am
just not understanding it.

not responsible for spelling. :-) any input on this would be most
appreciated.

--
73 de KU4YP "A clean ham shack is the
Mike Prevatt sign of a sick mind....."
Advanced Operator
Bartow, Florida Active HF/VHF/Digital

"ku4yp" wrote

in reference to station grounding, i have read keep the grounding
strap
as short as possible and not a multiple of a resonant length on the ham
bands. with that in mind, even if i ground pieces of equipment to
individual
ground rods, won't the complete grounding system be long? in my mind i am
looking around the room and seeing a grounding system being at least 12
feet
long, if i go along the perimeter of the desks (which are in a "U" shape
in
the room.

trying to grasp this in a practical sense. sorry if it is basic and i
am
just not understanding it.

Hi Mike. "Single Point ground"...this means *not* daisy-chaining to a bus
bar behind equipment tables if possible, and connecting each piece of
equipment to one (1) point that becomes the station's single point ground.
*Not* several ground rods from "individual" equipment. After you collect all
the station bonding straps at a single point, then you run to a very close
ground rod. After you hit that first single ground rod with the bus from all
station equipment, *then* you can branch out in a wide and plentiful ground
field that bonds to all your antenna, towers, masts, and last but definitely
not least, a direct low impedance and high current capable bond to the main
AC service ground rod of your home. The RF portion of the ground can
accomodate parallel connections to multiple ground rods in close to the
station if necessary. They must be part of the lightning protection ground,
never separate from it. There are tons of resources for this and lots of
experts here in this group. You can also try this website I built just for
those questions...one of the pages addresses RF grounds from the
transmitter.

http://members.cox.net/pc-usa/station/grounding.htm

73,

Jack
Virginia Beach

Jack Painter wrote:
"Single Point ground"...this means *not* daisy-chaining to a bus bar
behind equipment tables if possible, and connecting each piece of
equipment to one (1) point that becomes the station's single point
ground. *Not* several ground rods from "individual" equipment. After
you collect all the station bonding straps at a single point, then you
run to a very close ground rod. After you hit that first single ground
rod with the bus from all station equipment,

OK, I follow all that; but it doesn't fully address the original
poster's question about ground routing inside the operating room.

The question really is: what's the best *practical* way to route the
grounding from that single exit point to all the individual pieces of
equipment on the operating desks?

Even a small amateur station can be spread over several feet of desk;
L-shaped corner layouts are very common; and the OP is talking about an
even larger U-shaped layout. This means the distances from individual
items of equipment to the common the ground exit point can range from a
few feet up to even a few tens of feet (in terms of the minimum
practical distance around the rear of the desks). Also, modern amateur
stations are heavily cross-connected by signal/data/control cables,
which provide additional paths for damaging current surges to get inside
the equipment.

Everyone agrees (I hope) that the objective is to keep all the equipment
at the same potential, even when the local ground potential "bounces"
due to a nearby strike. Above all, the objective is to avoid current
surges going through the insides of individual items - those are what do
the damage.

For all the practical reasons outlined above, I don't believe there is a
completely "right" answer to the grounding problem inside the operating
room. Every practical method seems to have some drawbacks.

Based on your experience, what are your views about that specific
problem, Jack?



--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

"ku4yp" wrote
in reference to station grounding, i have read keep
the grounding strap as short as possible and not a multiple
of a resonant length on the ham bands. (etc)
__________________

Unless your antenna requires an earth ground as an integral part of its
design, the length or number of ham band wavelengths, or even the existence
of a metallic path to earth is irrelevant to the radiation characteristics
of the antenna itself.

Still, a good earth ground and other means are desirable to protect your
equipment from lightning transients, as developed by Jack Painter on his
informative website link earlier in this thread.

Here is a re-post of some earlier text I posted about the need for an
"antenna ground."

GW asked (clip):
How do you determine the quality of an antenna ground at HF
on an absolute basis? Not how well have I maximized what
Mother Nature gave me at my QTH by adding radials, but
how good is my ground compared to other stations' grounds
at other locations?

A low-resistance ground connection for a transmit antenna is important to
the received signal level only when the antenna design requires it as a
reference for its driven element, such as with the vertical radiators used
in MW broadcasting.

Most HF/VHF/UHF transmit antennas do not need, or use an earth ground
for efficient radiation. As practical proof of this, recall that airborne
antennas have no connection at all to earth ground, but still work just
fine.
And the transmit antennas used in commercial FM & TV broadcast are
installed at the top of a tall tower, many wavelengths (and ohms) above
earth potential. The tower is grounded for safety reasons, but the
radiation patterns and received signal levels from those antennas would be
the same even if that tower was not grounded.

RF

Visit http://rfry.org for FM broadcast RF system papers.

'as short as possible' it the important phrase. its not always possible to
keep it really short. another important part is keeping it as fat as
possible, meaning use heavy wire or, even better, something like copper
flashing, aluminum flashing or angle stock, or something like that. aluminum
angle stock that you find in 6-8' lengths in hardware stores makes excellent
ground busses, its easily drilled for connections to equipment, can be
easily bolted together at corners, and makes a nice neat installtion... use
the 1" or wider stuff if you can get it. do not use multiple ground rods
unless you also connect them all together outside... and if you do drive a
'station' ground rod be sure it is also connected outside with heavy
conductor to your existing power entrance ground. and while you are at it
make sure the power entrance is also connected to your water pipe coming in,
pool filter ground, outdoor light ground, and anything else grounded outside
the house.

"ku4yp" wrote in message
news:599_c.677$Va5.488@trnddc01...
i have a question.

in reference to station grounding, i have read keep the grounding
strap
as short as possible and not a multiple of a resonant length on the ham
bands. with that in mind, even if i ground pieces of equipment to
individual
ground rods, won't the complete grounding system be long? in my mind i am
looking around the room and seeing a grounding system being at least 12
feet
long, if i go along the perimeter of the desks (which are in a "U" shape
in
the room.

trying to grasp this in a practical sense. sorry if it is basic and i
am
just not understanding it.

not responsible for spelling. :-) any input on this would be most
appreciated.

--
73 de KU4YP "A clean ham shack is the
Mike Prevatt sign of a sick mind....."
Advanced Operator
Bartow, Florida Active HF/VHF/Digital

**** Post for FREE via your newsreader at post.usenet.com ****

"Richard Fry"
Still, a good earth ground and other means
are desirable to protect your equipment from
lightning transients...

Any 'Theory of Lightning' needs to be capable of including airplanes and
their general success at lightning protection - obviously sans earth
grounding. Typical airplanes get hits several times per year - often with
no damage. 'Airplanes' is such an obvious one-word counter example to
sooooooo many arguments about the "necessity" (sic) earth grounding...

I'm glad you used the words "...and other means" and "desirable". You're
not guilty.

Personally, I believe that a Faraday Cage (with appropriate entrance
protection) would be far more effective than fiddling with (optional) earth
grounds. Since most commercial buildings are metal or equivalent, this
gives the 'lightning professional' a huge advantage over the amateur (in his
wooden house). Much of what works for 'professional' lightning protection
works ~because~ the commercial installation is in a metal building. This
point needs to be acknowledged by those professing their experience while
advising the amateur in his wooden house full of lengthy, low voltage signal
wires. Having 20,000 amps surging (uh oh - 'surge' - that'll trigger off
the 'w_tom' idiobot - sorry) down the ground wire is obviously going to
cause 'sparks' in adjacent wires and cables and 'minor' equipment damage -
even with a perfect earth ground.




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"Ian White, G3SEK" wrote
Jack Painter wrote:
"Single Point ground"...this means *not* daisy-chaining to a bus bar
behind equipment tables if possible, and connecting each piece of
equipment to one (1) point that becomes the station's single point
ground. *Not* several ground rods from "individual" equipment. After
you collect all the station bonding straps at a single point, then you
run to a very close ground rod. After you hit that first single ground
rod with the bus from all station equipment,

OK, I follow all that; but it doesn't fully address the original
poster's question about ground routing inside the operating room.

The question really is: what's the best *practical* way to route the
grounding from that single exit point to all the individual pieces of
equipment on the operating desks?

Even a small amateur station can be spread over several feet of desk;
L-shaped corner layouts are very common; and the OP is talking about an
even larger U-shaped layout. This means the distances from individual
items of equipment to the common the ground exit point can range from a
few feet up to even a few tens of feet (in terms of the minimum
practical distance around the rear of the desks). Also, modern amateur
stations are heavily cross-connected by signal/data/control cables,
which provide additional paths for damaging current surges to get inside
the equipment.

Everyone agrees (I hope) that the objective is to keep all the equipment
at the same potential, even when the local ground potential "bounces"
due to a nearby strike. Above all, the objective is to avoid current
surges going through the insides of individual items - those are what do
the damage.

For all the practical reasons outlined above, I don't believe there is a
completely "right" answer to the grounding problem inside the operating
room. Every practical method seems to have some drawbacks.

Based on your experience, what are your views about that specific
problem, Jack?
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Right Ian, having equipment spread out over a wide area is an undesireable
condition, but a reality for many operators. Running 3" wide or greater
copper strapping in individual paths to one single bus "collector" is a
challenge, but one worth trying. Equipment stacked or racked together could
certainly be "grouped" and a common bonding strap run for each group to the
SPG. But 20 linear feet of bus bar could have huge transient voltages
developed across it from a nearby strike. As in a few hundred thousand volts
between supposedly "grounded' equipment. Hence the importance of all
equipment connecting to the same ground point, not via a long run of common
bus bar to that ground point. Make your compromises according to your
individual requirements and station layout. Just realize that in a nearby-by
strike, lightning will find the weak points in any system and exploit that
weakness to the fullest possibility. I experience numerous nearby strikes
that probably raise the ground potential several hundred thousand volts, and
expose my entire ground system to those voltages. If there were large
potential differences between even bonded equipments in the station, deadly
hazards would exist. It's all about choices, and we all have to make them.

Best regards,

Jack Painter
Virginia Beach VA

i thank you all for the comments.

to tie into the electirical service will be a pain as the electrical
gound is on the total oposite end of the house from the shack. i'll have to
work something out there. water pipe grounding will not be a problem.

i can see i have much more reading to do.

thanks agian, mike


--
73 de KU4YP "A clean ham shack is the
Mike Prevatt sign of a sick mind....."
Advanced Operator
Bartow, Florida Active HF/VHF/Digital
"Dave" wrote in message
...
'as short as possible' it the important phrase. its not always possible
to
keep it really short. another important part is keeping it as fat as
possible, meaning use heavy wire or, even better, something like copper
flashing, aluminum flashing or angle stock, or something like that.
aluminum
angle stock that you find in 6-8' lengths in hardware stores makes
excellent
ground busses, its easily drilled for connections to equipment, can be
easily bolted together at corners, and makes a nice neat installtion...
use
the 1" or wider stuff if you can get it. do not use multiple ground rods
unless you also connect them all together outside... and if you do drive a
'station' ground rod be sure it is also connected outside with heavy
conductor to your existing power entrance ground. and while you are at it
make sure the power entrance is also connected to your water pipe coming
in,
pool filter ground, outdoor light ground, and anything else grounded
outside
the house.

"ku4yp" wrote in message
news:599_c.677$Va5.488@trnddc01...
i have a question.

in reference to station grounding, i have read keep the grounding
strap
as short as possible and not a multiple of a resonant length on the ham
bands. with that in mind, even if i ground pieces of equipment to
individual
ground rods, won't the complete grounding system be long? in my mind i
am
looking around the room and seeing a grounding system being at least 12
feet
long, if i go along the perimeter of the desks (which are in a "U" shape
in
the room.

trying to grasp this in a practical sense. sorry if it is basic and
i
am
just not understanding it.

not responsible for spelling. :-) any input on this would be most
appreciated.

--
73 de KU4YP "A clean ham shack is the
Mike Prevatt sign of a sick mind....."
Advanced Operator
Bartow, Florida Active HF/VHF/Digital

ku4yp wrote:
i have a question.

in reference to station grounding, i have read keep the grounding strap
as short as possible and not a multiple of a resonant length on the ham
bands. with that in mind, even if i ground pieces of equipment to individual
ground rods, won't the complete grounding system be long? in my mind i am
looking around the room and seeing a grounding system being at least 12 feet
long, if i go along the perimeter of the desks (which are in a "U" shape in
the room.

W1MCE replies:

I have used a 1/2 inch copper pipe mounted along the back edge of the
table[s] holding my station equipment.

The case of each piece of equipment is connected directly to the copper
pipe using 1 inch braided strap about 6 to 12 inches long depending on
equipment size. This pipe provides an equipotential plane for all my
equipment. [Another method would be to install a thin copper sheath on
top of your desk/tables and connect directly to it for the equipotential
plane.]

Now, how to connect the equipotential plane to brown dirt [earth] is the
next issue. You are correct that it is desirable to keep this
'non-resonant' on the bands you operate. There are two issues here that
need to be addressed. First, if you are close to the earth ground then a
simple #6 AWG wire to a ground rod is adequate. Second, if you are
higher than 1/4 wavelength at the highest frequency of interest use two
#6 AWG wires OF DIFFERENT LENGTHS, not harmonically related, connected
to the ground rod. The different lengths assure that the equivalent
connection is NOT RESONANT.

In very fortunate cases an additional station ground is not required!
Believe it or not! ... My station is located on the ground floor in the
family [my] TV room right under the electrical distribution panel. My
120 VAC line comes directly from the service entrance through about 3
feet of wire. The 240 VAC for my amplifier comes directly from the
service entrance through 4 feet of wire. The service box is 'earthed' by
a NEC compliant connection. My connections to the service box are
therefore very short.

A major point of caution is required. The NEC requires ONLY ONE ground
connection. Multiple ground connections introduce VERY SERIOUS ground
loops that may violate the NEC criteria. This opens a VERY LARGE loop
hole in your home owner's insurance policy. If you are adding a second
earth [ground] connection at your station use an isolation transformer
to break up the ground loops in the basic 120 VAC connection. Consult
with an electrician regarding your local and NEC codes.

It is noted that station grounding and antenna counterpoise construction
are two different things. I am not addressing the counterpoise issue.

Dave Shrader wrote:
. . .
A major point of caution is required. The NEC requires ONLY ONE ground
connection. Multiple ground connections introduce VERY SERIOUS ground
loops that may violate the NEC criteria. This opens a VERY LARGE loop
hole in your home owner's insurance policy. If you are adding a second
earth [ground] connection at your station use an isolation transformer
to break up the ground loops in the basic 120 VAC connection. Consult
with an electrician regarding your local and NEC codes.
. . .

My NEC book is getting pretty old now, 1990, but at that time, multiple
grounds were often not only permitted, but required. And a *minimum*
spacing was sometimes specified.

For example, section 250-84, Resistance of Made Electrodes: "A single
electrode consisting of a rod, pipe, or plate which does not have a
resistance to ground of 25 ohms or less shall be augmented by one
additional electrode of any of the types specified in Sections 250-81 or
250-83. Where multiple rod, pipe, or plate electrodes are installed to
meet the requirements of this section, they shall be not less than 6
feet (1.83m) apart."

Or section 250-81(a), Metal Underground Water Pipe: ". . .A metal
underground water pipe shall be supplemented by an additional electrode
of a type specified in Section 250-81 or in Section 250-83. The
supplemental electrode shall be permitted to be bonded to the grounding
electrode conductor, the grounded service-entrance conductor, the
grounded service raceway, any grounded sevice enclosure, or the interior
metal water piping at any convenient point."

When I replaced the service (in 1979) in my 1952 house, the system
ground was a water pipe connection and I was required to add a ground
rod. Neither was considered adequate in itself; both were required by
the code at that time.

I agree wholeheartedly about consulting an electrician. Non-electricians
(including me) often have mistaken ideas about the content of the NEC.
It doesn't hurt to have an up to date copy of the NEC for reference,
either, if you anticipate doing any of the work yourself.

Roy Lewallen, W7EL