On of the main causes of "common mode" [CM] noise is "differential
mode" [DM] noise that gets
converted to into common mode noise.

There are two main means of conversion.

The least common but most powerful occurs when a device like a laptop
is powered by the AC
mains and is connected to a phone line or Ethernet cable. The noise
from the power supply is
coupled back on the AC mains and into the telephone or Ethernet line,
and this forms a very
effective unintentional antenna. Any device that is connected to the
AC mains and any other
conductor is very likely to be a source of significant common mode
noise. This other conductor
can be telephone, Ethernet, Coax Cable for DBS or CATV, or any other
conductor. While we
are used to thinking of antennas as needing to be an odd quarter wave
length, effective antennas
can in fact be much shorter. Ground leads approaching 1/20 f a wave
length are effective
radiators.

The most common conversion of DM to CM occurs due to the imbalance in
the AC mains. I have
looked at over 20 different brands of 3 conductor cable used for
domestic residential wiring. Some
of this is new and some dates back to cable that is at least 30 years
old.


There are 3 main types:
Type 1: H-G-N arranged in a triangle with the ground between the hot
and neutral.
Type 2: H-N-G arranged with the hot on one side, the neutral in the
middle and the ground
on the other outer side next to the neutral.
Type 3: The H and N run, more or less in parallel, with the ground
weaving back and forth from
one to the other.

At the start of this investigation I assumed the primary reason for DM
to CM was caused by the
interruption in what I had perceived "the natural balanced
transmission characteristics" of AC
power cords. I do accept that when the conductors that are nominally
on 3/8" centers are spread
for outlets, switches, light fixtures, and the mess inside a breaker
panel, don't help the situation.
However it became apparent in some tests at a new home with all of the
AC and other cables
installed, but with no connection to the real world via power,
telephone or CATV, that my original
idea was flawed.

I now believe the primary cause is the extremely unbalanced
"transmission line" effects caused
by the ground conductor's relation ship to the purported balanced 2
conductor hot and neutral.

In a simple test last night an Electrician friend brought over a ~100'
piece of Romax of the type 1
construction. We(he) laid it out on the surface of ground and I used a
Balun to couple the Romax
to my R2000 operating on battery power. I terminated the far end with
a non inductive 120 Ohm resistor. When this experiment is performed
using 2 conductor zip or speaker cable there is
minimal reception of all but my local 770KHz MW pest. However with the
Romex reception of even
distant MW and HF signals was significant. Grounding the Romex
"ground' conductor did not
have a significant effect.

I suspect that if we could wire our homes with 2 conductor cable and
run a separate grounding
conductor we could reduce the conversion of DM to CM. Since the NEC
would frown on such
a scheme and because the costs would be extraordinary the only
effective way to stop the
conversion of DM into CM is to eliminate or at least reduce DM noise
at the source.

I hope to put a more detailed version of this experiment along with
the new house test results
on Will's stopRFI page "some day real soon".

Terry

ding the "Ground" conductor changed the

On Sep 26, 8:39 am, wrote:
On of the main causes of "common mode" [CM] noise is "differential
mode" [DM] noise that gets
converted to into common mode noise.

There are two main means of conversion.

The least common but most powerful occurs when a device like a laptop
is powered by the AC
mains and is connected to a phone line or Ethernet cable. The noise
from the power supply is
coupled back on the AC mains and into the telephone or Ethernet line,
and this forms a very
effective unintentional antenna. Any device that is connected to the
AC mains and any other
conductor is very likely to be a source of significant common mode
noise. This other conductor
can be telephone, Ethernet, Coax Cable for DBS or CATV, or any other
conductor. While we
are used to thinking of antennas as needing to be an odd quarter wave
length, effective antennas
can in fact be much shorter. Ground leads approaching 1/20 f a wave
length are effective
radiators.

The most common conversion of DM to CM occurs due to the imbalance in
the AC mains. I have
looked at over 20 different brands of 3 conductor cable used for
domestic residential wiring. Some
of this is new and some dates back to cable that is at least 30 years
old.

There are 3 main types:
Type 1: H-G-N arranged in a triangle with the ground between the hot
and neutral.
Type 2: H-N-G arranged with the hot on one side, the neutral in the
middle and the ground
on the other outer side next to the neutral.
Type 3: The H and N run, more or less in parallel, with the ground
weaving back and forth from
one to the other.

At the start of this investigation I assumed the primary reason for DM
to CM was caused by the
interruption in what I had perceived "the natural balanced
transmission characteristics" of AC
power cords. I do accept that when the conductors that are nominally
on 3/8" centers are spread
for outlets, switches, light fixtures, and the mess inside a breaker
panel, don't help the situation.
However it became apparent in some tests at a new home with all of the
AC and other cables
installed, but with no connection to the real world via power,
telephone or CATV, that my original
idea was flawed.

I now believe the primary cause is the extremely unbalanced
"transmission line" effects caused
by the ground conductor's relation ship to the purported balanced 2
conductor hot and neutral.

In a simple test last night an Electrician friend brought over a ~100'
piece of Romax of the type 1
construction. We(he) laid it out on the surface of ground and I used a
Balun to couple the Romax
to my R2000 operating on battery power. I terminated the far end with
a non inductive 120 Ohm resistor. When this experiment is performed
using 2 conductor zip or speaker cable there is
minimal reception of all but my local 770KHz MW pest. However with the
Romex reception of even
distant MW and HF signals was significant. Grounding the Romex
"ground' conductor did not
have a significant effect.

I suspect that if we could wire our homes with 2 conductor cable and
run a separate grounding
conductor we could reduce the conversion of DM to CM. Since the NEC
would frown on such
a scheme and because the costs would be extraordinary the only
effective way to stop the
conversion of DM into CM is to eliminate or at least reduce DM noise
at the source.

I hope to put a more detailed version of this experiment along with
the new house test results
on Will's stopRFI page "some day real soon".

Terry

ding the "Ground" conductor changed the

Terry,

Insightful Report and a good read.

Alas, the NEC is all about Electrical Safety
and not concerned about RFI Suppression.

I always thought that if I were having a Home Built
and could do the Electrical Wiring myself. It would
be better to use Type "AC" Wire through-out the House
http://homerenovations.about.com/od/.../artbxwire.htm
then the "NM" Plastic Covered Stuff.
http://homerenovations.about.com/od/...artromexnm.htm

Check-Out the "STOP RFI" Group on Yahoo !
http://groups.yahoo.com/group/stopRFI/

On Sep 26, 12:16 pm, RHF wrote:
On Sep 26, 8:39 am, wrote:



On of the main causes of "common mode" [CM] noise is "differential
mode" [DM] noise that gets
converted to into common mode noise.

There are two main means of conversion.

The least common but most powerful occurs when a device like a laptop
is powered by the AC
mains and is connected to a phone line or Ethernet cable. The noise
from the power supply is
coupled back on the AC mains and into the telephone or Ethernet line,
and this forms a very
effective unintentional antenna. Any device that is connected to the
AC mains and any other
conductor is very likely to be a source of significant common mode
noise. This other conductor
can be telephone, Ethernet, Coax Cable for DBS or CATV, or any other
conductor. While we
are used to thinking of antennas as needing to be an odd quarter wave
length, effective antennas
can in fact be much shorter. Ground leads approaching 1/20 f a wave
length are effective
radiators.

The most common conversion of DM to CM occurs due to the imbalance in
the AC mains. I have
looked at over 20 different brands of 3 conductor cable used for
domestic residential wiring. Some
of this is new and some dates back to cable that is at least 30 years
old.

There are 3 main types:
Type 1: H-G-N arranged in a triangle with the ground between the hot
and neutral.
Type 2: H-N-G arranged with the hot on one side, the neutral in the
middle and the ground
on the other outer side next to the neutral.
Type 3: The H and N run, more or less in parallel, with the ground
weaving back and forth from
one to the other.

At the start of this investigation I assumed the primary reason for DM
to CM was caused by the
interruption in what I had perceived "the natural balanced
transmission characteristics" of AC
power cords. I do accept that when the conductors that are nominally
on 3/8" centers are spread
for outlets, switches, light fixtures, and the mess inside a breaker
panel, don't help the situation.
However it became apparent in some tests at a new home with all of the
AC and other cables
installed, but with no connection to the real world via power,
telephone or CATV, that my original
idea was flawed.

I now believe the primary cause is the extremely unbalanced
"transmission line" effects caused
by the ground conductor's relation ship to the purported balanced 2
conductor hot and neutral.

In a simple test last night an Electrician friend brought over a ~100'
piece of Romax of the type 1
construction. We(he) laid it out on the surface of ground and I used a
Balun to couple the Romax
to my R2000 operating on battery power. I terminated the far end with
a non inductive 120 Ohm resistor. When this experiment is performed
using 2 conductor zip or speaker cable there is
minimal reception of all but my local 770KHz MW pest. However with the
Romex reception of even
distant MW and HF signals was significant. Grounding the Romex
"ground' conductor did not
have a significant effect.

I suspect that if we could wire our homes with 2 conductor cable and
run a separate grounding
conductor we could reduce the conversion of DM to CM. Since the NEC
would frown on such
a scheme and because the costs would be extraordinary the only
effective way to stop the
conversion of DM into CM is to eliminate or at least reduce DM noise
at the source.

I hope to put a more detailed version of this experiment along with
the new house test results
on Will's stopRFI page "some day real soon".

Terry

ding the "Ground" conductor changed the

Terry,

Insightful Report and a good read.

Alas, the NEC is all about Electrical Safety
and not concerned about RFI Suppression.

I always thought that if I were having a Home Built
and could do the Electrical Wiring myself. It would
be better to use Type "AC" Wire through-out the Househttp://homerenovations.about.com/od/electrical/a/artbxwire.htm
then the "NM" Plastic Covered Stuff.http://homerenovations.about.com/od/...artromexnm.htm

Check-Out the "STOP RFI" Group on Yahoo !
http://groups.yahoo.com/group/stopRFI/
.
STOP RFI =http://groups.yahoo.com/group/stopRFI/
.
~ RHF
.

There is some thought that the soft steel of the armor flex type
cables may hurt more then it helps. The spiral wrap is a real concern.
For some general research on conduit and transfer impedance please
see:
http://www.emcconsultinginc.com/docs/conduitse.PDF

I have the url at home of a company that makes "Armor flex" that has a
real tinned copper braid and is damn near RF proof.
I will dig it out and post it.

The electrician that I mentioned just completed a wiring contract
where all the conduit was copper tubing.
Very Expensive! This was for a computer lab that I suspect deals with
unusual data. There were three layers
of screening, the EMC certification lab I worked at for a while only
had 2!, and the AC mains go through more
filters then I have ever seen.

I suspect the one reason why my common mode noise issue is so low is
my ground ring. It offers a very low resistance/impedance
to the earth. And at least one circuit in every room has a 6AWG aux
bonding to the ground ring.

But I still think the best solution is to stop DM at the source.

Terry

On Sep 26, 12:16 pm, RHF wrote:
On Sep 26, 8:39 am, wrote:



On of the main causes of "common mode" [CM] noise is "differential
mode" [DM] noise that gets
converted to into common mode noise.

There are two main means of conversion.

The least common but most powerful occurs when a device like a laptop
is powered by the AC
mains and is connected to a phone line or Ethernet cable. The noise
from the power supply is
coupled back on the AC mains and into the telephone or Ethernet line,
and this forms a very
effective unintentional antenna. Any device that is connected to the
AC mains and any other
conductor is very likely to be a source of significant common mode
noise. This other conductor
can be telephone, Ethernet, Coax Cable for DBS or CATV, or any other
conductor. While we
are used to thinking of antennas as needing to be an odd quarter wave
length, effective antennas
can in fact be much shorter. Ground leads approaching 1/20 f a wave
length are effective
radiators.

The most common conversion of DM to CM occurs due to the imbalance in
the AC mains. I have
looked at over 20 different brands of 3 conductor cable used for
domestic residential wiring. Some
of this is new and some dates back to cable that is at least 30 years
old.

There are 3 main types:
Type 1: H-G-N arranged in a triangle with the ground between the hot
and neutral.
Type 2: H-N-G arranged with the hot on one side, the neutral in the
middle and the ground
on the other outer side next to the neutral.
Type 3: The H and N run, more or less in parallel, with the ground
weaving back and forth from
one to the other.

At the start of this investigation I assumed the primary reason for DM
to CM was caused by the
interruption in what I had perceived "the natural balanced
transmission characteristics" of AC
power cords. I do accept that when the conductors that are nominally
on 3/8" centers are spread
for outlets, switches, light fixtures, and the mess inside a breaker
panel, don't help the situation.
However it became apparent in some tests at a new home with all of the
AC and other cables
installed, but with no connection to the real world via power,
telephone or CATV, that my original
idea was flawed.

I now believe the primary cause is the extremely unbalanced
"transmission line" effects caused
by the ground conductor's relation ship to the purported balanced 2
conductor hot and neutral.

In a simple test last night an Electrician friend brought over a ~100'
piece of Romax of the type 1
construction. We(he) laid it out on the surface of ground and I used a
Balun to couple the Romax
to my R2000 operating on battery power. I terminated the far end with
a non inductive 120 Ohm resistor. When this experiment is performed
using 2 conductor zip or speaker cable there is
minimal reception of all but my local 770KHz MW pest. However with the
Romex reception of even
distant MW and HF signals was significant. Grounding the Romex
"ground' conductor did not
have a significant effect.

I suspect that if we could wire our homes with 2 conductor cable and
run a separate grounding
conductor we could reduce the conversion of DM to CM. Since the NEC
would frown on such
a scheme and because the costs would be extraordinary the only
effective way to stop the
conversion of DM into CM is to eliminate or at least reduce DM noise
at the source.

I hope to put a more detailed version of this experiment along with
the new house test results
on Will's stopRFI page "some day real soon".

Terry

ding the "Ground" conductor changed the

Terry,

Insightful Report and a good read.

Alas, the NEC is all about Electrical Safety
and not concerned about RFI Suppression.

I always thought that if I were having a Home Built
and could do the Electrical Wiring myself. It would
be better to use Type "AC" Wire through-out the Househttp://homerenovations.about.com/od/electrical/a/artbxwire.htm
then the "NM" Plastic Covered Stuff.http://homerenovations.about.com/od/...artromexnm.htm

Check-Out the "STOP RFI" Group on Yahoo !
http://groups.yahoo.com/group/stopRFI/
.
STOP RFI =http://groups.yahoo.com/group/stopRFI/
.
~ RHF
.

Another article on conduits for EMI control.

I found the most important comment was the
need for a insulated out jacket to be very interesting.


http://www.powerqualityanddrives.com/emi_rfi/

Terry

In article .com,
wrote:

On of the main causes of "common mode" [CM] noise is "differential
mode" [DM] noise that gets
converted to into common mode noise.

There are two main means of conversion.

The least common but most powerful occurs when a device like a laptop
is powered by the AC
mains and is connected to a phone line or Ethernet cable. The noise
from the power supply is
coupled back on the AC mains and into the telephone or Ethernet line,
and this forms a very
effective unintentional antenna. Any device that is connected to the
AC mains and any other
conductor is very likely to be a source of significant common mode
noise. This other conductor
can be telephone, Ethernet, Coax Cable for DBS or CATV, or any other
conductor. While we
are used to thinking of antennas as needing to be an odd quarter wave
length, effective antennas
can in fact be much shorter. Ground leads approaching 1/20 f a wave
length are effective
radiators.

The most common conversion of DM to CM occurs due to the imbalance in
the AC mains. I have
looked at over 20 different brands of 3 conductor cable used for
domestic residential wiring. Some
of this is new and some dates back to cable that is at least 30 years
old.


There are 3 main types:
Type 1: H-G-N arranged in a triangle with the ground between the hot
and neutral.
Type 2: H-N-G arranged with the hot on one side, the neutral in the
middle and the ground
on the other outer side next to the neutral.
Type 3: The H and N run, more or less in parallel, with the ground
weaving back and forth from
one to the other.

At the start of this investigation I assumed the primary reason for DM
to CM was caused by the
interruption in what I had perceived "the natural balanced
transmission characteristics" of AC
power cords. I do accept that when the conductors that are nominally
on 3/8" centers are spread
for outlets, switches, light fixtures, and the mess inside a breaker
panel, don't help the situation.
However it became apparent in some tests at a new home with all of the
AC and other cables
installed, but with no connection to the real world via power,
telephone or CATV, that my original
idea was flawed.

I now believe the primary cause is the extremely unbalanced
"transmission line" effects caused
by the ground conductor's relation ship to the purported balanced 2
conductor hot and neutral.

In a simple test last night an Electrician friend brought over a ~100'
piece of Romax of the type 1
construction. We(he) laid it out on the surface of ground and I used a
Balun to couple the Romax
to my R2000 operating on battery power. I terminated the far end with
a non inductive 120 Ohm resistor. When this experiment is performed
using 2 conductor zip or speaker cable there is
minimal reception of all but my local 770KHz MW pest. However with the
Romex reception of even
distant MW and HF signals was significant. Grounding the Romex
"ground' conductor did not
have a significant effect.

I suspect that if we could wire our homes with 2 conductor cable and
run a separate grounding
conductor we could reduce the conversion of DM to CM. Since the NEC
would frown on such
a scheme and because the costs would be extraordinary the only
effective way to stop the
conversion of DM into CM is to eliminate or at least reduce DM noise
at the source.

I hope to put a more detailed version of this experiment along with
the new house test results
on Will's stopRFI page "some day real soon".

Terry

ding the "Ground" conductor changed the


Nice post! Thanks.
-j

On Sep 27, 2:27 am, RHF wrote:
On Sep 26, 10:03 am, wrote:

On Sep 26, 12:16 pm, RHF wrote:

On Sep 26, 8:39 am, wrote:

On of the main causes of "common mode" [CM] noise is "differential
mode" [DM] noise that gets
converted to into common mode noise.

There are two main means of conversion.

The least common but most powerful occurs when a device like a laptop
is powered by the AC
mains and is connected to a phone line or Ethernet cable. The noise
from the power supply is
coupled back on the AC mains and into the telephone or Ethernet line,
and this forms a very
effective unintentional antenna. Any device that is connected to the
AC mains and any other
conductor is very likely to be a source of significant common mode
noise. This other conductor
can be telephone, Ethernet, Coax Cable for DBS or CATV, or any other
conductor. While we
are used to thinking of antennas as needing to be an odd quarter wave
length, effective antennas
can in fact be much shorter. Ground leads approaching 1/20 f a wave
length are effective
radiators.

The most common conversion of DM to CM occurs due to the imbalance in
the AC mains. I have
looked at over 20 different brands of 3 conductor cable used for
domestic residential wiring. Some
of this is new and some dates back to cable that is at least 30 years
old.

There are 3 main types:
Type 1: H-G-N arranged in a triangle with the ground between the hot
and neutral.
Type 2: H-N-G arranged with the hot on one side, the neutral in the
middle and the ground
on the other outer side next to the neutral.
Type 3: The H and N run, more or less in parallel, with the ground
weaving back and forth from
one to the other.

At the start of this investigation I assumed the primary reason for DM
to CM was caused by the
interruption in what I had perceived "the natural balanced
transmission characteristics" of AC
power cords. I do accept that when the conductors that are nominally
on 3/8" centers are spread
for outlets, switches, light fixtures, and the mess inside a breaker
panel, don't help the situation.
However it became apparent in some tests at a new home with all of the
AC and other cables
installed, but with no connection to the real world via power,
telephone or CATV, that my original
idea was flawed.

I now believe the primary cause is the extremely unbalanced
"transmission line" effects caused
by the ground conductor's relation ship to the purported balanced 2
conductor hot and neutral.

In a simple test last night an Electrician friend brought over a ~100'
piece of Romax of the type 1
construction. We(he) laid it out on the surface of ground and I used a
Balun to couple the Romax
to my R2000 operating on battery power. I terminated the far end with
a non inductive 120 Ohm resistor. When this experiment is performed
using 2 conductor zip or speaker cable there is
minimal reception of all but my local 770KHz MW pest. However with the
Romex reception of even
distant MW and HF signals was significant. Grounding the Romex
"ground' conductor did not
have a significant effect.

I suspect that if we could wire our homes with 2 conductor cable and
run a separate grounding
conductor we could reduce the conversion of DM to CM. Since the NEC
would frown on such
a scheme and because the costs would be extraordinary the only
effective way to stop the
conversion of DM into CM is to eliminate or at least reduce DM noise
at the source.

I hope to put a more detailed version of this experiment along with
the new house test results
on Will's stopRFI page "some day real soon".

Terry

ding the "Ground" conductor changed the

Terry,

Insightful Report and a good read.

Alas, the NEC is all about Electrical Safety
and not concerned about RFI Suppression.

I always thought that if I were having a Home Built
and could do the Electrical Wiring myself. It would
be better to use Type "AC" Wire through-out the Househttp://homerenovations.about.com/od/electrical/a/artbxwire.htm
then the "NM" Plastic Covered Stuff.http://homerenovations.about.com/od/...artromexnm.htm

Check-Out the "STOP RFI" Group on Yahoo !
http://groups.yahoo.com/group/stopRFI/
.
STOP RFI =http://groups.yahoo.com/group/stopRFI/
.
~ RHF
.

Another article on conduits for EMI control.

- I found the most important comment was the
- need for a insulated out jacket to be very interesting.
-
-http://www.powerqualityanddrives.com/emi_rfi/
-
- Terry

The need for and Outer Insulated Jacket would only apply
to Metal Framed Buildings. The common Wooden Framed
House would not have the Metal-to-Metal contact problem
and the resulting RFI / EMF re-radiation by the Building's
Metal Frame itself. - imho ~ RHF
.

True for older homes, but around here, in Central Kentucky, many homes
are being
built with metal "2X4". While my latest investigation was at 750K
house which was all
wood except for some bracing in the roof trusses, most of the
'affordable' 250K used
the metal "2X4". In every home around here the AC mains approached the
heating and
coolnig duct work closer then I like, but non had contact. In two of
the lower end 250K
homes, not wired by my friend, the Romex was in almost direct contact
with the
copper water pipes.

Another reason I like the newer non spiral wrapped armor that is
formed from extruded
aluminum is that with age the edges of the wrap tend to corrode. My
parents house,
built in 1948 and upgraded to matalic 1960 has RFI issues that
weren't there when I
was a SWL there.Some checking revealed that in two places the armored
cable
had a light coating of rust. And those two runs re radiated a mix of
two not so close
MW signals, 590 and 630. The mixing appears to be solely a product of
the corroded
sections.

I have several experiments I am waiting in severe frustration because
of my bum right arm.
I hope to do some real world tests with various AC cables and see if
matalic is better
then Romex. Given the 1/20 of a wavelength maximum ground lead "rule"
it will be interesing
to see how armor cable fairs. I suspect it will radiate nearly as bad
as Romex becasue
of both the length and the typical poor bonding between the metal
armor and outlet and
junction boxes.

Terry


Terry