I know this has been addressed on the group before but I remain confused.

I will string a dipole in the trees. The coax shield will be earth
grounded, as well as the balun and lightening arrestor.

Now, in the 2nd floor shack, I've read that running a ground line from
equipment 15 feet or more (in this case) to an earth ground will bring
RF into the shack and be a potent source for TVI, etc.

My choice, then, is to use the ground on the mains.

Given that the shield is earth grounded on the antenna and the equipment
is grounded to the mains, isn't this a good scenario for ground loop?

Seems like a catch-22.

My own gut says safety first, lower risk of RF issues after-the-fact by
? what ?

I remember suggestions of coiling the ground wire in an RF choke,
multiple ground lines of various lenghts to mess with harmonics.
Ferrite beads? Chicken blood and a black cat?

John

On Thu, 09 Mar 2006 23:28:12 -0500, jawod wrote:

I know this has been addressed on the group before but I remain confused.

I will string a dipole in the trees. The coax shield will be earth
grounded, as well as the balun and lightening arrestor.

The BalUn? As for each, or the rest, where will that ground be? Back
in the shack? Out below the antenna?

Now, in the 2nd floor shack, I've read that running a ground line from
equipment 15 feet or more (in this case) to an earth ground will bring
RF into the shack and be a potent source for TVI, etc.

Poor choice of reading. It should have been extensive enough to
resolve your confusion.

My choice, then, is to use the ground on the mains.

Not always the best choice, but all such considerations have issues.

Given that the shield is earth grounded on the antenna and the equipment
is grounded to the mains, isn't this a good scenario for ground loop?

You better believe it.

Seems like a catch-22.

My own gut says safety first, lower risk of RF issues after-the-fact by
? what ?

You first have to figure out what ground means.

I remember suggestions of coiling the ground wire in an RF choke,
multiple ground lines of various lenghts to mess with harmonics.
Ferrite beads? Chicken blood and a black cat?

Hi John,

A dipole certainly doesn't need a ground connection. Neither does a
choke or BalUn. The lightning arrestor - obviously. But you are not
going to do that through house wiring.... are you? No. So where?

Starting with that last point, the ground needs to be close by the
arrestor, and given the coax can be laid out anywhere, it may as well
pass nearby your service ground where you can provide a short ground
lead to the arrestor.

Then follows the possibility of the ground loop. This will only arise
if the safety ground carries current (it shouldn't) or the neutral
return to that service ground does, and has some resistance to boot.
It stands to reason there will be current, what remains to be seen is
if there is appreciable resistance (a poor connection).

Try as you might to avoid it, you WILL have a ground connection to the
service ground from your rig (unless you are floating free on battery
power and have absolutely no other accessories going to your rig).
When you connect your arrestor to ground, this will guarantee a loop
configuration. Any potential (pun intended) problem is strictly a
matter of this resistance and current.

I'll cut it short with this as questions are sure to follow.

73's
Richard Clark, KB7QHC

jawod wrote:
I know this has been addressed on the group before but I remain confused.

My own gut says safety first, lower risk of RF issues after-the-fact by
? what ?

I remember suggestions of coiling the ground wire in an RF choke,
multiple ground lines of various lenghts to mess with harmonics.
Ferrite beads? Chicken blood and a black cat?


John,

You have been misled and confused by bad information.



Richard Clark has given you good advice.


The only antenna that requires an RF ground is an antenna with a single
conductor feedline worked against ground, or an antenna that is poorly
designed or constructed.

The only reasons to have a hamshack ground, unless you are trying to
band-aid an antenna that is improperly constructed or feed a longwire,
are electrical safety and lightning.

Electrical safety can be taken care of by using a three wire outlet
with grounding to the sagfety ground, and by following national codes.
National codes require your station ground be bonded to the power mains
entrance ground. We are not suposed to have two isolated grounds
according to NEC, and it is a bad idea to have isolated grounds for
lightning, safety, and RFI reasons.

I'm afraid all the talk about ground loops and such have confused you.

Try reading this:

http://www.w8ji.com/ground_systems.htm

73 Tom

jawod wrote:
I know this has been addressed on the group before but I remain confused.

I will string a dipole in the trees. The coax shield will be earth
grounded, as well as the balun and lightening arrestor.

Now, in the 2nd floor shack, I've read that running a ground line from
equipment 15 feet or more (in this case) to an earth ground will bring
RF into the shack and be a potent source for TVI, etc.

My choice, then, is to use the ground on the mains.

Given that the shield is earth grounded on the antenna and the equipment
is grounded to the mains, isn't this a good scenario for ground loop?

Seems like a catch-22.

My own gut says safety first, lower risk of RF issues after-the-fact by
? what ?

I remember suggestions of coiling the ground wire in an RF choke,
multiple ground lines of various lenghts to mess with harmonics. Ferrite
beads? Chicken blood and a black cat?

John
Reading the two responses so far...I'll get my advice elsewhere.
Typical internet group response...mildly insulting and of no direct
value. I first have to know what ground means? Whatever.
Imaginary numbers apparently require imaginary minds.

jawod wrote:

I know this has been addressed on the group before but I remain confused.

I will string a dipole in the trees. The coax shield will be earth
grounded, as well as the balun and lightening arrestor.

Now, in the 2nd floor shack, I've read that running a ground line from
equipment 15 feet or more (in this case) to an earth ground will bring
RF into the shack and be a potent source for TVI, etc.

My choice, then, is to use the ground on the mains.

Given that the shield is earth grounded on the antenna and the equipment
is grounded to the mains, isn't this a good scenario for ground loop?

Seems like a catch-22.

My own gut says safety first, lower risk of RF issues after-the-fact by
? what ?

I remember suggestions of coiling the ground wire in an RF choke,
multiple ground lines of various lenghts to mess with harmonics.
Ferrite beads? Chicken blood and a black cat?

John


John,

So you are taking a balanced aerial, a dipole, chuck it onto a balun and the
feed it with a coax. Nothing wrong with that...

There should not be any "involvement" by the coax in the functionality of
that dipole. The grounding of the coax are for shielding purpose only and
as such, you ground the coax at one of the terminations, in your case, the
transceiver.

Building regs normally demand that the house's mains ground should be
connected to a ground rod somewhere, normally at a central point.

Assuming that every level adds 2.5m, you are sitting 5 meter up. Even if you
ground your rig with a separate connection to a ground rod, you'll still be
electrically 5 meter away from ground ( at least ).

You will always have RF in your shack PERIOD, It's just a question where
it is and how you discover it. It's either RF current or RF Voltage. As the
RF voltage is what you normally discovers by having a "hot" key or
transceiver, you need to phase shift the ground connection of the coax in
time so you have a max current at your rig instead of high voltage.

This is solved by using an artificial ground. Buy or build one, they are
dirt simple. MFJ sells one.

The artificial ground is basically a capacitor and an inductor in series
with the coax SHIELD(!). Both cap and coil is variable/tunable.
By changing the cap and coil, you can move the RF Voltage and RF current +/-
90 degrees. You just adjust for max RF current at your operating frequency.

This worked fine at the 32nd floor for me...


Cheers


Dan / M0DFI

One way to beat this is to tune with low power and touch the
rig. Every few days increase the power until you have built up
a tolerance to the RF tingle.

You could also try this with the household power, starting at
2 or three volts, and increasing it gradually over time until
you build up your immunity to electric shock as well.

Irv VE6BP :-)

There is absolutely no reason to have an RF ground unless:

1.) You are end feeding a single wire antenna that is brought into the
shack

2.) The two conductor feedline you have brought in, be it coax or open
wire, is connected to an antenna that is not properly designed or
installed

The safety ground is required. The RF ground is a band-aid for
something else being wrong.

73 Tom

Irv Finkleman wrote:
One way to beat this is to tune with low power and touch the
rig. Every few days increase the power until you have built up
a tolerance to the RF tingle.

You could also try this with the household power, starting at
2 or three volts, and increasing it gradually over time until
you build up your immunity to electric shock as well.

Irv VE6BP :-)

I tried this approach several years ago...got up to about half a kilovolt...

but my wife complained that my glow was keeping her up at night.

wrote:
There is absolutely no reason to have an RF ground unless:

1.) You are end feeding a single wire antenna that is brought into the
shack

2.) The two conductor feedline you have brought in, be it coax or open
wire, is connected to an antenna that is not properly designed or
installed

The safety ground is required. The RF ground is a band-aid for
something else being wrong.

73 Tom

Tom,

If we assume that there is a well matched antenna: twin line to balun,
coax to transceiver. My RF concern was that a long line to ground would
serve as an antenna to bring RF into shack. If this is not the case, or
if this is easily dealt with, great.

The mains box is on the opposite side of the house...that ground is not
conveniently located.

My coax will go thru a lightening arrestor (Polyphase) which will be
earth grounded. If I run a low gauge wire from that earth ground to the
main box ground, then this is prevents ground loop? What if the
distance to the mains box is 60 feet?

John

On Sun, 12 Mar 2006 22:39:51 -0500, jawod wrote:

If I run a low gauge wire from that earth ground to the
main box ground, then this is prevents ground loop? What if the
distance to the mains box is 60 feet?

Hi John,

This is required by code. Violate code and insurance can dump your
policy faster than a lightning strike.

The whole point of that wire is to prevent ground loops - this one
being the mother of all loops. If and when lighting gets snubbed by
your arrestor, it will bury that charge into this inferior ground (the
non-code unconnected ground that is), lift that ground's potential,
and that potential will follow its way into the shack (along the
shield) to find your safety ground (which is far better suited for
that path) and you might happen to be sitting on the shoulder of that
current superhighway.

The resistive earth path between your arrestor ground and service
ground is not nearly as attractive as the path from safety ground,
through power supply, through chassis, through transmission line
shield to the arrestor. It is a rare power supply that breaks that
path's DC continuity, and a rarer one that RF isolates it both. Unless
you are running solely on battery, no charger, and no accessories
connected to the rig - there is a path to ground that lightning will
find as an alternative.

60 feet is trivial for safety (the RF in lighting is more LF or MF
than HF).

73's
Richard Clark, KB7QHC