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

"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

Jack Painter wrote:
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.

Thanks very much for those thoughts, Jack.

As I'd guessed, you had some good suggestions, but you can see their
practical problems too. The same applies to an alternative method, which
is to group related items of equipment as closely as possible, and
connect them by the shortest possible straps to a large sheet of metal.

The key feature is that this sheet should be *very wide*, to create a
very low inductance and help minimize any voltage drops along its
length. Conductor thickness doesn't matter in this location, so a sheet
of copper-clad PC board is fine. It's also very easy to solder short
grounding straps onto the PC board, and move them around without having
to disconnect the whole sheet to drill it.

Some people put the sheet on the table, and the gear on top of the
sheet. If there is a shelf carrying another level of equipment above,
another practical way is to fasten the sheet to the underside of the
shelf.

The reason why conductor thickness doesn't matter in this location is
that we don't expect full-bore lightning surges through the station
itself. The ground bonding at the common service entrance should have
diverted the main surge safely to ground, so the equipment bonding
inside the station should only need to deal with very much smaller
currents - smaller, but still large enough to damage sensitive
electronics. Also, the higher-frequency components of the surge will
only run along the surface anyway, so what matters most is width and
surface area rather than thickness of copper.

As Jack says, busbars are a particular invitation to develop voltage
drops along their length. This "ground-sheet" system accepts there will
be some voltage drop along its length, but does everything practicable
to minimize it. A wide sheet is vastly better than busbars, and solid
copper busbars are a particular waste of money - a large sheet of scrap
PC board will do it far better, for almost nothing.

If I had the luxury of a large station, I'd use these sheets as part of
a wider-scale "grouping" system, as Jack suggests.


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.

In this climate, lightning is actually quite a minor hazard. What has
driven me to organize and bond equipment together is the need to control
RFI due to ground currents (of which I generate rather a lot). What's
good for the one is generally good for the other... and often good for
received noise reduction too.


--
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.

**** 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.




-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
*** Usenet.com - The #1 Usenet Newsgroup Service on The Planet! ***
http://www.usenet.com
Unlimited Download - 19 Seperate Servers - 90,000 groups - Uncensored
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

'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

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

On Sat, 04 Sep 2004 20:28:58 GMT, "ku4yp" wrote:

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

When we had an electrician upgrade the incoming electrical service box
on my mother's house (circa 1960), he ran a large 8 gauge wire from
the box at the end of the garage, along the wall of the house all the
way to the incoming water line from the street near the other end of
the basement, where he tied it to ground next to the water meter.

The National Electrical Code has changed, and those in older houses
might consider upgrading to current code (no pun intended) even if not
actually required.

In industrial situations, I have had to deal with ground loop
problems, which are a PITA to find. Do your grounding correctly, and
you will be safer, and have an easier time of it.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom