In article
,
Telamon wrote:

In article ,
"Robert11" wrote:

"Telamon" wrote in
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gy .com...
In article , "Robert11"
wrote:

Hi,

In the category of "why the heck didn't I do that years ago,"
thought I'd relate my experience with a new HF receiving only
antenna.

Up to now, have had a simple random length wire running around
the four sides of my attic. Worked, and was able to receive many
stations, but was always disappointing.

Bought the PAR EF-SWL antenna, and just put it up outside as an
Inverted-L, and away from the house by about 75 feet or so.
Coax run-in to the receiver. Wow, what an incredible
difference. The noise level is way, way down.

Question; The PAR ends in a Balun, from which I have a wire to
a ground bar I pounded into the ground next to it. From there,
the coax starts.

I also have a chassis ground from the radio to a nearby cold
water pipe. Have been putting it on and off trying to decide if
it helps to have this additional ground, or hurts. There is of
course the ground loop questions, etc. about having two grounds
(the earth ground by the Balun, and this one to the cold water
pipe)

Hate to admit it, but am having trouble deciding if it helps. At
times, and for different freq's, I sort of think it either
helps, or makes no difference, at other time, perhaps a bit more
noisy.

Most of the time, I believe, it makes absolutely no difference
whether this chassis receiver ground wire is on or off.

**Anyone have any thoughts or comments regarding having this
additional ground ? **

Should it make a difference ? I tend to think it shouldn't
matter, as they usually suggest grounding the coax, Also, right
where it enters the house, which would be pretty much
equivalent.

There is, of course, also the grounding pin of the AC power
line, which, pretty much ends up at the same place, namely a
cold water pipe via a ground/neutral wire, from the AC Service
Box.

Curious about what all you experts think re these
configurations. Not too sharp with this, and would appreciate
any thoughts on.

Congratulations on the improved antenna.

You don't say which radio you own but chances are the third prong
(ground) is the radio chassis so another ground wire to the radio
case won't make a difference.

The important ground is at the antenna UNUN.

Hi,

Sorry i forgot to mention: have a JRC NRD 545

You're undoubtedly correct. Why, though, provide an additional
ground connection off of the barrier / terminal strip ?

The ground prong is for safety. Manufactures have two ways to go.
Either make the entire exterior non-conductive with a minimum value
of voltage insulation and use a polarized plug or go with the third
ground prong to earth ground that is not normally supposed to carry
current. This ground prong goes to the conductive cabinet of the
unit. If a hot wire inside the unit touches the cabinet it then
causes a short circuit blowing a fuse or breaker preventing
electrocution. The white return wire is supposed to carry the normal
operating current for the device.

In the USA at least the black wire is the hot wire with gold contacts
on connectors, white wire is the return with silver colored contacts
and green is the ground. Often the screw to put the ground wire on is
painted green or marked in a obvious way. Wall sockets and power
cords to appliances are all polarized to maintain this relationship
of hot, return and earth ground.

I can see some people are still confused about some points.

Current travels in a loop. DC batteries, AC power mains, RF current all
travel in a loop. People recognize this when they draw a circuit as in
basic circuit analysis but it is forgotten when applied to either RF or
AC power mains supply.

The power mains is AC or alternating current. This voltage is stepped
up and down throughout the power distribution system with transformers.
Now you must understand that when power goes through a transformer it
is now isolated from ground. The two wires from the transformer
secondary are hot or have voltage potential RELATIVE to EARTH GROUND.

Now this relationship of both secondary leads from the last transformer
to your house is usually modified at the input panel. Now here come
another concept where things purposely change. One of these secondary
wires is connected to EARTH GROUND through a GROUND ROD. This wire
becomes the "NEUTRAL" because it is neutralized to ground through the
connection to the ground rod. Now the other secondary wire has
alternating voltage on it RELATIVE to EARTH GROUND and is called the
hot wire.

Notice that the voltage relationship between each wire to earth ground
is changed through the use of the ground rod. Black is the hot, white
is the return or neutral and green is the safety earth ground. Normally
all the power flows on the black and white wires. If you connect a
light bulb to a white wire and the other side to a ground rod there is
no power to light it. If you connect the black wire and ground rod it
will light up.

Also notice that the voltage relationship between the two wire does not
change only the voltage from each wire to EARTH GROUND. This is a
common mode voltage shift relative to ground. Either transformer
secondary wire could have been chosen to be the return.

Final step down power pole also usually has a ground wire on it and so
do your neighbors. Since you now have multiple grounds on a power line
to your house and there is a voltage drop along the line this generates
a voltage gradient in the earth between the power system ground rods.
Now you know how it happens that you will see a voltage potential
across separate ground rods.

The two wires, black and white, are the AC mains power circuit. All
loads go between these two wires. Black and white are the source and
return, which all loads are across.

Now we consider the third wire or EARTH GROUND wire in the three wiring
system used today. This third and separate wire is also connected to a
bonded strip that is the EARTH GROUND in the power panel. There are TWO
BONDED STRIPS in the panel, one for return and the other for earth
ground. This green earth ground wire is supposed to connect to the
conductive cabinet of any appliance plugged into the AC power mains.
Now if the hot wire contacts the cabinet there is a short circuit to
earth ground blowing the fuse or breaker in the power panel. This
prevents AC power from going through YOU to EARTH GROUND.

This green wire is for safety purposes and does not normally but can
carry the return current to power a device or appliance in case of an
internal fault.

--
Telamon
Ventura, California

On Sun, 23 Apr 2006 22:41:12 GMT, Telamon
wrote:


Now this relationship of both secondary leads from the last transformer
to your house is usually modified at the input panel. Now here come
another concept where things purposely change. One of these secondary
wires is connected to EARTH GROUND through a GROUND ROD. This wire
becomes the "NEUTRAL" because it is neutralized to ground through the
connection to the ground rod. Now the other secondary wire has
alternating voltage on it RELATIVE to EARTH GROUND and is called the
hot wire.


Now if the hot wire contacts the cabinet there is a short circuit to
earth ground blowing the fuse or breaker in the power panel. This
prevents AC power from going through YOU to EARTH GROUND.

This green wire is for safety purposes and does not normally but can
carry the return current to power a device or appliance in case of an
internal fault.

Have you ever had to deal with a 3 wire 3 phase power drop (i.e.
without a neutral)? Not very common. Drives electricians nuts.

On Mon, 24 Apr 2006 02:51:52 GMT, m II wrote:

David wrote:

Have you ever had to deal with a 3 wire 3 phase power drop (i.e.
without a neutral)? Not very common. Drives electricians nuts.


Why would it do that? A three wire feed implies a balanced load, such as
a three phase motor, charger or welder supply. Voltage drop is measured
line to line and line current is still measured the same way, as are
power factor numbers.

The only difference in a three phase motor connection is assuring
correct direction for motor rotation. Some things break in a dramatic
fashion if turned the wrong way.


Where does the 120 come from?

David wrote in
:

On Mon, 24 Apr 2006 02:51:52 GMT, m II wrote:

David wrote:

Have you ever had to deal with a 3 wire 3 phase power drop (i.e.
without a neutral)? Not very common. Drives electricians nuts.


Why would it do that? A three wire feed implies a balanced load, such as
a three phase motor, charger or welder supply. Voltage drop is measured
line to line and line current is still measured the same way, as are
power factor numbers.

The only difference in a three phase motor connection is assuring
correct direction for motor rotation. Some things break in a dramatic
fashion if turned the wrong way.


Where does the 120 come from?


Pennsylvania Power & Light Co.


SC

David wrote:
On Mon, 24 Apr 2006 02:51:52 GMT, m II wrote:


David wrote:


Have you ever had to deal with a 3 wire 3 phase power drop (i.e.
without a neutral)? Not very common. Drives electricians nuts.


Why would it do that? A three wire feed implies a balanced load, such as
a three phase motor, charger or welder supply. Voltage drop is measured
line to line and line current is still measured the same way, as are
power factor numbers.

The only difference in a three phase motor connection is assuring
correct direction for motor rotation. Some things break in a dramatic
fashion if turned the wrong way.



Where does the 120 come from?


The cycles of each phase are out by that many electrical degrees in
relation to each other. I've never seen 120V three wire 3 phase. The
lowest voltage 3 phase 3 wire I've experienced is 208 volts.

If there is a 'wye' connection with a central white leg, (3 phase 4
wire) then you will see 120 volts from a hot leg to this white (neutral)
and 208 volts between any two hots.


The numerical stuff is covered he

http://encyclopedia.laborlawtalk.com/Three_phase

The really scary math happens with major short circuits on a leg causing
asymmetric fault currents.

Uneven power factor loads in the phases can make some interesting vector
diagrams..

it's been a while since school...sigh...

mike

On Tue, 25 Apr 2006 04:52:54 GMT, m II wrote:




The cycles of each phase are out by that many electrical degrees in
relation to each other. I've never seen 120V three wire 3 phase. The
lowest voltage 3 phase 3 wire I've experienced is 208 volts.

If there is a 'wye' connection with a central white leg, (3 phase 4
wire) then you will see 120 volts from a hot leg to this white (neutral)
and 208 volts between any two hots.


The numerical stuff is covered he

http://encyclopedia.laborlawtalk.com/Three_phase

The really scary math happens with major short circuits on a leg causing
asymmetric fault currents.

Uneven power factor loads in the phases can make some interesting vector
diagrams..

it's been a while since school...sigh...

mike
Don't tell me, tell them.

Metinks e' (me) mights looks aroond for some pen pal galfriends on
Ventura Beach.
cuhulin

My married Irish lady friend wayyyyyy over yonder across the big
pond,she is emailing me now.I am busy!
cuhulin