Okay, since I'm installing an entirely new setup, what I'm looking for
here is the best way to ground my equipment and a large center-fed
wire dipole.

Lets start with the shack first. The radio and speaker are both
connected to the house ground through their power cords. To provide
better RF grounding, I'm thinking of everything (including radio &
speaker) connected with 1" copper braid to two salted (for increased
conductivity) ground rods just outside. Is that sufficient?

Next, to reduce the likelihood of lightning reaching the shack, the
only thing I can think of is a lightning arrester inline to two
additional salted ground rods, with the coax disconnected when not
used. I don't believe RF is an issue with a dipole, so is this
sufficient for lighting protection?

Give me your opinions. Am I missing something? Is there a better way?

stewart / w5net

wrote in message
...
Okay, since I'm installing an entirely new setup, what I'm looking for
here is the best way to ground my equipment and a large center-fed
wire dipole.

Lets start with the shack first. The radio and speaker are both
connected to the house ground through their power cords. To provide
better RF grounding, I'm thinking of everything (including radio &
speaker) connected with 1" copper braid to two salted (for increased
conductivity) ground rods just outside. Is that sufficient?

Those 2 rods must be connected directly to your house power service ground
with (i think) #4 or larger wire. This is a serious safety issue. This
connection can NOT be through the green wire in the shack, it must be to the
rod/wire that comes into the house.

Note also, this is NOT an 'RF ground'... There really is no such thing as an
RF ground, ground rods are all about power line and lightning safety.
Salting rods is really not necessary unless you are in exceptionally poor
soil, and then its more the water you have to use to keep them moist that
helps the most... even salt in dry soil can't help you.


Next, to reduce the likelihood of lightning reaching the shack, the
only thing I can think of is a lightning arrester inline to two
additional salted ground rods, with the coax disconnected when not
used. I don't believe RF is an issue with a dipole, so is this
sufficient for lighting protection?

again, don't put in separate rods, all rods must be hooked together and to
the service entrance ground. if you have coax lightning arresters they
should be tied to the same ground as everything else where they enter the
shack. disconnecting the coax from the radio can't hurt, but may not help
much either.

Stewart,

The advice Dave gave is good.

There is no perfect grounding installation, every one is a compromise to
some degree. So I will describe a "close to" optimum setup and yours will
be a compromise, but try to make it the minimum compromise you can.

There are three grounds to be aware of. Safety, RF, and lightning or surge.

1. You are already covered for safety with the green wire ground.

2. You don't ground your equipment for RF grounding. Only some antennas
need one, such as a vertical. Your dipole does not.

3. Lightning and surge protection ground - There should be only one
grounding POINT, and it has already been established. It is the ground the
power company uses. Any other ground you establish has to be connected to
that one, as Dave described. The objective of surge protection is to keep
the fireball outside of your house!! If you don't allow surges into your
house it really simplifies the job of equipment protection.

All conductors that come into your house need to be protected with proper
surge devices. That includes telephone, cable tv, your 220 volt power, and
your dipole coax. Ideally you have a plate (some think it has to be copper,
but it can be aluminum as well) mounted right at the ground rod and on it
you have a telephone line protector, a cable tv protector, and your coax
lightning arrestor. Polyphaser and others make such devices. But the most
vital of all is one that goes on your power line. Why ? Because any of
these conductors can bring a lightning surge into your house, but the one
that is most likely is the power line. It is called a whole house protector
and it usually is installed by an electrician at the circuit breaker panel.
The telephone line probably has gas tubes protecting it. Cable TV will have
a little block, hopefully tied in already but it doesn't have gas tubes in
it so it can use help.

In the way of compromises, usually you have to bring in the coax at some
other point. If you do, you ground the coax shield with the lightning
arrestor to a ground rod, but as Dave described that rod has to be tied to
the power company ground. Etc. etc.

If you had residual surges that you were concerned with, AFTER you did all
the above, then the next step is to bond all of your equipment together and
tie it to the ground point.

As you now know, if your shack is not located next to the ground point
mentioned above, you have to provide a good and short conductor to that
point.

Good luck.



Rick K2XT

wrote:
Okay, since I'm installing an entirely new setup, what I'm looking for
here is the best way to ground my equipment and a large center-fed
wire dipole.

Lets start with the shack first. The radio and speaker are both
connected to the house ground through their power cords. To provide
better RF grounding, I'm thinking of everything (including radio &
speaker) connected with 1" copper braid to two salted (for increased
conductivity) ground rods just outside. Is that sufficient?

Maybe a few questions might help clarify what you're trying to do, and
what your objectives are.

What is connecting the radio and speaker to an earth ground doing? Are
you hoping to provide an alternate path if the AC line shorts to the
case inside? The green-wire ground does that very nicely.
Are you thinking that RF currents will flow from radio chassis to
ground? The RF current should be in the antenna feedline, only.

In general, an earth ground for your equipment isn't needed.
(Consider this.. an airplane has lots of radio gear, external antennas,
etc. and gets hit by lightning, and still keeps going, and there's no
connection to earth ground)


Next, to reduce the likelihood of lightning reaching the shack, the
only thing I can think of is a lightning arrester inline to two
additional salted ground rods, with the coax disconnected when not
used. I don't believe RF is an issue with a dipole, so is this
sufficient for lighting protection?


Do you care about electrical code compliance?
There are specific rules in Article 800 of the NEC.

There's several issues here. What's the overall goal? protect the house
from burning down (but sacrifice the gear if needed) or protect the gear
at all costs? Protecting against direct strike on antenna or induced
voltages from nearby strikes?

House burning down is handled by using a listed antenna discharge unit
(ADU) connected to a suitable lightning dissipation ground. (salted rods
are not a suitable lightning dissipation ground, but more anon) The ADU
has to be mounted outside, close to the point of entry into the house.

The ADU will make sure that most of the lightning current is safely
conducted through something other than the flammable stuff of which your
house is built. But, it might not save your gear (for a variety of
reasons).

If you want to have a better chance of saving the gear (aside from
disconnecting, in which case you need to short the incoming antenna
connections to the lightning ground, as well.. don't just leave it
open), you want to do what is good practice for EMI/EMC anyway. Have
everything referred to a common potential. In a sort of idealized
scheme, you'd have your AC receptacle mounted on a conductive plate
which also has the antenna feedthrough. The plate is bonded to the
electrical service ground (so the breaker trips if there's a short
inside your gear) and is also connected to the lightning ground (since
that's where the antenna surge is going to go). A listed transient
suppressor is connected to the AC line and the grounded plate as well.

Now, all the gear (radio, speaker, etc.) is all connected to this one
plate, so if lightning hits, and there's a many kilovolt drop in the
grounding wire, everything goes together, and you've minimized the
voltage between any two conductors connected to the radio.

It's the airplane thing... the lightning hits the airplane, but
everything inside the airplane stays at the same potential relative to
itself so there's no problem.

You'll hear a lot about needing a big flat ribbon for lightning ground.
Maybe, maybe not. Here's why. If it's any length at all, the lower
inductance of the flat ribbon is still high enough that the voltage rise
at the panel (L di/dt) from the lightning impulse is still hundreds or
thousands of volts. If your system can take 1000V rise, it can probably
take 5000V, so the absolute rise isn't as important. And, a higher
inductance, higher resistance conductor actually slows down the
transient a bit, which reduces the currents induced by the magnetic
field. Lightning may be a huge current, but it's short duration, so it
actually doesn't take a very big wire to carry it (AWG 10, for instance)
without melting.

The key here is to understand what you're trying to do, and how you're
doing it. Don't blindly assume that since radiotelegraph stations with
beverages and longwires in 1920 used big ground rods that's what you
should be doing in your shack today.

---

Now.. about rods, ground, salting, etc.

Your ground should be a concrete encased grounding electrode (aka Ufer
ground), which is what the electrical code requires. Rods can be used
for supplemental grounds, but you have to worry about making suitable
connections (exothermic welds, etc.), the soil drying out, and the
generally high resistance of ground rods. Salting eventually washes
out, so isn't worthwhile in most cases. There are soil additives (e.g.
bentonite) that are used in connection with grounding, but they work by
being very hygroscopic and keeping the soil conductivity high by keeping
water in the soil. But overall, the Ufer ground is your friend: low
resistance, reliable, large area (so current density is low.. no
"smoking rods").

The code requires that ALL grounds be bonded together with a suitable
conductor.



Give me your opinions. Am I missing something? Is there a better way?

stewart / w5net

Thanks for the replies, Dave, Rick, and Jim. Since my ideas didn't go
over so well, perhaps it's best to just describe my setup and then
listen to any suggestions. Since I'm not an electrical engineer, do
try to keep things simple.

As I said earlier, the radio and speaker are both connected to the
house ground through their power cords. I've also installed an
inverted V dipole in the back yard (the only place it will fit). The
center (feedpoint) of the antenna is attached to the roof on the
second floor (about twenty feet above the ground) and the two ends run
out to the two corners of the backyard. That's the best I can
accomplish given local antenna restrictions.

My house is located on a hill with a top floor entrance and living
area. Below that is another floor level with the backyard, with a
basement below that.

The radio will be located in the living room on the top floor, again
one floor above the backyard. The coax (RG-8X) will run out a window
on the second floor to the center (feedpoint) of the antenna attached
to the roof just outside (a run of roughly 15-ft).

Now, where (if any) should I add grounding to that setup? I was going
to add a lightning arrester to the coax just before it enters the
house (fed into two ground rods), but will forego that since none seem
overly thrilled about the idea.

By the way, a Yeasu technician once recommended salting ground rods to
resolve a poor grounding situation at the time, so I've been doing
that ever since (can't hurt), especially during the dry summer months.
Adding water is pretty obvious, so didn't think I needed to spell that
out, Dave.

stewart / w5net

noname wrote:
Thanks for the replies, Dave, Rick, and Jim. Since my ideas didn't go
over so well, perhaps it's best to just describe my setup and then
listen to any suggestions. Since I'm not an electrical engineer, do
try to keep things simple.

As I said earlier, the radio and speaker are both connected to the
house ground through their power cords. I've also installed an
inverted V dipole in the back yard (the only place it will fit). The
center (feedpoint) of the antenna is attached to the roof on the
second floor (about twenty feet above the ground) and the two ends run
out to the two corners of the backyard. That's the best I can
accomplish given local antenna restrictions.

My house is located on a hill with a top floor entrance and living
area. Below that is another floor level with the backyard, with a
basement below that.

The radio will be located in the living room on the top floor, again
one floor above the backyard. The coax (RG-8X) will run out a window
on the second floor to the center (feedpoint) of the antenna attached
to the roof just outside (a run of roughly 15-ft).

Now, where (if any) should I add grounding to that setup? I was going
to add a lightning arrester to the coax just before it enters the
house (fed into two ground rods), but will forego that since none seem
overly thrilled about the idea.

By the way, a Yeasu technician once recommended salting ground rods to
resolve a poor grounding situation at the time, so I've been doing
that ever since (can't hurt), especially during the dry summer months.
Adding water is pretty obvious, so didn't think I needed to spell that
out, Dave.

stewart / w5net

Do you have metal water pipes upstairs with continuity to a spot near
the ground rods downstairs? If so you can run a strap to your shack
upstairs, and another from the water pipe to the ground rods downstairs.

You need an RF ground (as the safety ground is the 3 prong Edison.) MFJ
makes an artificial ground. Do you use a balun at the antenna
feedpoint? How do you tune the inverted-V?

d

Do you have metal water pipes upstairs with continuity to a spot near
the ground rods downstairs? If so you can run a strap to your shack
upstairs, and another from the water pipe to the ground rods downstairs.


bad plan.

1) Water pipes may or may not have good electrical conductivity.
2) You're asking for leakage current to flow in the pipes: corrosion is
one possibility, shocks to people touching the pipes or plumbing is another.
3) If you also have the third wire ground to chassis, good chance you've
now created a big receiving loop consisting of the pipes and your house
electrical systems. Not good.

4) Using plumbing systems for electrical safety bonding/grounding is not
recommended in any of the recent editions of the electrical code, and is
certainly not a good idea for RF currents.



You need an RF ground (as the safety ground is the 3 prong Edison.) MFJ
makes an artificial ground.

If it's a coax fed antenna, there should be no need for any sort of RF
ground in the shack.


Do you use a balun at the antenna
feedpoint? How do you tune the inverted-V?

Good RF chokes on the coax at the feedpoint and at the point of entry
would go a long way to eliminating any "RF in the shack" problems. A
couple 2.4" 31 mix cores with half a dozen turns on them, for instance.

Whether the V is tuned or not won't have any effect on RFI or grounding.

On Mon, 04 May 2009 13:14:04 +0200, noname wrote:

Now, where (if any) should I add grounding to that setup? I was going
to add a lightning arrester to the coax just before it enters the
house (fed into two ground rods), but will forego that since none seem
overly thrilled about the idea.

Hi Stewart,

A very good description of your set-up. You are already grounded
through a the haphazard path of your AC outlet - if you chose to use
three prong connections, if your outlet is in fact grounded, if your
equipment actually has a safety ground to chassis. A lot of "ifs,"
hence my use of "haphazard."

By deliberately adding a ground wire going to an ad-hoc ground rod,
you can easily introduce problems. The worst of which could be
lethal, but that extreme is unlikely (except it might only be resolved
at the coroner's inquest).

Consult code for grounding requirements.

The minor problems include ground loops that can plague your listening
and/or your contacts asking what that strange music is in the
background of your transmission. The loops can burn out wiring in
your rig (actually, more like traces on cards). The oddities that
arise from ad-hoc grounding scroll out on a list of complaints that
many come here to find solution for.

By the way, a Yeasu technician once recommended salting ground rods to
resolve a poor grounding situation at the time, so I've been doing
that ever since (can't hurt), especially during the dry summer months.
Adding water is pretty obvious, so didn't think I needed to spell that
out, Dave.

That sounds like a fantasy. If this thread doesn't grow suitably to
fill in the vacuum of information, you can do a search in google
groups, for this group, using the key word GROUND and CODE.

73's
Richard Clark, KB7QHC

Jim Lux wrote:


Do you use a balun at the antenna
feedpoint? How do you tune the inverted-V?

Good RF chokes on the coax at the feedpoint and at the point of entry
would go a long way to eliminating any "RF in the shack" problems. A
couple 2.4" 31 mix cores with half a dozen turns on them, for instance.

Whether the V is tuned or not won't have any effect on RFI or grounding.

A BalUn would help a lot.

Since we are sticklers for the NEC, Homey needs a #6 wire from where the
transmission line enters the dwelling to an 8' copper clad rod driven
into the earth, as close as practicable.

In article ,
Richard Clark wrote:

By the way, a Yeasu technician once recommended salting ground rods to
resolve a poor grounding situation at the time, so I've been doing
that ever since (can't hurt), especially during the dry summer months.
Adding water is pretty obvious, so didn't think I needed to spell that
out, Dave.

That sounds like a fantasy. If this thread doesn't grow suitably to
fill in the vacuum of information, you can do a search in google
groups, for this group, using the key word GROUND and CODE.

73's
Richard Clark, KB7QHC

It really depends on the area that your trying to build the RF Ground
on, or into. Here in Alaska much of the earth (Dirt) is just plain
Silica Sand, and rock, with very little mineralite in it, and is about
as effective an RF Ground as a piece of Glass. We use Dipoles a lot just
for that reason as they don't required an RF Ground to work against to
radiate effectively. In some areas where Marconi type Antennas are used,
and one MUST have an effective RF Ground, we have used Chicken Wire
panels laid flat out from the base to 1/4 Wave at the lowest Frequency
of intended use, and then Salted the dirt to add to the effective
conductance of the Ground plane untill the chicken wire Rusts to the
point of leaving just the conductive material in the top of the dirt.
The Commercial AutoTune Antenna Tuners really don't work well without an
effective RF Ground to work against, as the Microcode that runs them,
can't deal with the very non-stable RF Grounding Systems. There are a
number of ways to get single-ended Autotuners to tune Balanced Dipole
type Antennas, and those are used as well. Much of the work done in the
commercial MF/HF Communications Antennas Systems here in Alaska, was
pioneered by the Engineering Staffs of the old Northern Radio Company,
and then continued by Stephens Engineering Associates. (SEA) Both
outfits were leaders in Bush Communications here in Alaska, in their day.

--
Bruce in alaska
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