"zeno" wrote in message ...
Walking around using an old RatShack portable short wave radio I was able
to track down an unusual noise source (an incessant clicking that was all
over 40-160m. I was able to aim the portable antenna at various wires
while walking around. This particular noise turned out to be someone's
bad telephone. When the telephone was disconnected, this loud
click-click-click disappeared. Seems like that bad telephone was somehow
"transmitting" this noise back through the phone lines.

Admittedly the noise from the power lines here are much more difficult to
pin down and seems to change with the weather. It can be very annoying
and discouraging. There is a high voltage transformer right here next to
the house, which means those hv lines are coming right down my driveway.
Designing an antenna which is not even close to parallel to these power
lines has helped somewhat. I am hoping the new 160m full wave loop which
will be further away is going to be a big improvement. I am just hoping
that the ladder line feed to this loop will not also pick up the noise.
If so I will have to change that feedline to coax which will be a
compromise.

Impoving my RF ground and making sure it was totally independent from the
A.C. safety ground at the house main has helped also. My primary RF
ground cable goes through a hole in the floor at the station and
immediately to a copper pipe driven in under the house. This first run is
shorter than 6'. This first copper pipe is then tied to several others at
about 10' apart to make up for the fact that they are only driven 5' into
the ground. Make sure your RF ground is independent of the house AC
safety ground. I also use a constant voltage transformer and a good power
conditioner because the AC here is a mess.

-bill


Hi Bill,

Isolating RF ground from AC ground may be a solution in your individual
circumstance, but it is not recommended or safe under normal conditions.
Single Point Common Ground means what it says and nothing is "isolated".
That begs for problems not the least of which is ground loops.

I do exactly the same thing under my shack WRT multiple RF ground rods as
you have and a very short drop to them as well - that elminates the chance
for 1/4 wave multiples in the ground sytem to raise the impedance
drastically. But according to best available practices and electrical code
everything (antenna ground rods, RF ground rods, and service-mains ground
rod) are all tied together. Understand that this in no way contributes in
any way to "noise" in the receivers, and it can reduce noise significantly.
It also helps minimize lightning damage, at least according to all the
codes, writings, and many experts in this group.

73's

Jack
Virginia Beach

OK, I guess I have to do more thinking about this, even though my head is
already totally spinning from the fact that there seems to be blatant
discrepancies between expert opinions out there. I am new to this ng and have
much to learn.

I am not sure who to believe at this point.

The book says "one common ground", AC safety AND RF, all one thing. This seems
to be what is being advised here as well. This seems to be consistent with
building codes. That is the "law", the politically correct physics, and what
one needs to say in print or be liable, etc.

Then I turn around, and experienced hams are telling me the exact opposite, eg.
not to tie the RF ground to the house AC safety ground. To tie the RF ground to
the house safety ground rod means a much longer run and thus the potential
problems of 1/4 wavelength resonance also mentioned here.

By the way, I am using an older Kenwood TS530S (until I get some experience and
decide to invest in a more current rig). Are current rigs now always with three
pronged polarized/grounded plugs? My unit here has a two prong non-polarized ac
plug, just like the old audio tube amps I still use for hi-fi.

This whole "ground" thing and its history is quite mysterious, controversial,
and confusing to say the least.


In 1953 when I was first a novice, I used a bizarre little homemade transmitter
with one 117N7 tube which only plugged into one side of the house current!!!!
and then used an earth ground and antenna. I am, in retrospect, amazed I am
here and alive to tell the story.

Where is Tesla when we need him......



Just curious, if I were to take a light bulb and connect ONE terminal to the
hot side of an ac house outlet and then connect the other terminal to a ground
rod driven into the ground in the middle of a forest somewhere where trees fall
without anyone there to hear them, will the light bulb light up?

bill (feeling a bit ungrounded at the moment.....)


Jack Painter wrote:

"zeno" wrote in message ...
Walking around using an old RatShack portable short wave radio I was able
to track down an unusual noise source (an incessant clicking that was all
over 40-160m. I was able to aim the portable antenna at various wires
while walking around. This particular noise turned out to be someone's
bad telephone. When the telephone was disconnected, this loud
click-click-click disappeared. Seems like that bad telephone was somehow
"transmitting" this noise back through the phone lines.

Admittedly the noise from the power lines here are much more difficult to
pin down and seems to change with the weather. It can be very annoying
and discouraging. There is a high voltage transformer right here next to
the house, which means those hv lines are coming right down my driveway.
Designing an antenna which is not even close to parallel to these power
lines has helped somewhat. I am hoping the new 160m full wave loop which
will be further away is going to be a big improvement. I am just hoping
that the ladder line feed to this loop will not also pick up the noise.
If so I will have to change that feedline to coax which will be a
compromise.

Impoving my RF ground and making sure it was totally independent from the
A.C. safety ground at the house main has helped also. My primary RF
ground cable goes through a hole in the floor at the station and
immediately to a copper pipe driven in under the house. This first run is
shorter than 6'. This first copper pipe is then tied to several others at
about 10' apart to make up for the fact that they are only driven 5' into
the ground. Make sure your RF ground is independent of the house AC
safety ground. I also use a constant voltage transformer and a good power
conditioner because the AC here is a mess.

-bill

Hi Bill,

Isolating RF ground from AC ground may be a solution in your individual
circumstance, but it is not recommended or safe under normal conditions.
Single Point Common Ground means what it says and nothing is "isolated".
That begs for problems not the least of which is ground loops.

I do exactly the same thing under my shack WRT multiple RF ground rods as
you have and a very short drop to them as well - that elminates the chance
for 1/4 wave multiples in the ground sytem to raise the impedance
drastically. But according to best available practices and electrical code
everything (antenna ground rods, RF ground rods, and service-mains ground
rod) are all tied together. Understand that this in no way contributes in
any way to "noise" in the receivers, and it can reduce noise significantly.
It also helps minimize lightning damage, at least according to all the
codes, writings, and many experts in this group.

73's

Jack
Virginia Beach

On Sat, 17 Apr 2004 18:42:44 GMT, zeno wrote:

Hi Bill,

By the points offered:

Then I turn around, and experienced hams are telling me the exact opposite, eg.
not to tie the RF ground to the house AC safety ground.

Experienced Amateurs (as distinct from experienced Professionals).

To tie the RF ground to
the house safety ground rod means a much longer run and thus the potential
problems of 1/4 wavelength resonance also mentioned here.

The basic confusion that arises is in the distinction between RF and
Mains ground. You can keep your RF ground rod (add some radials to it
to actually make it RF ground) as long as you tie it to the Mains
ground (usually in close proximity to the drop and meter). The
distance between THESE two points is immaterial RF wise as your RF
ground will insure little or no RF current travels to the Mains
ground. In THIS sense, they are separate.

If there is noise (RF) on the Mains, it may seek your RF ground
through this connection, but as long as you are not sharing it (you
are not using this lead to both connect your equipment AND connect the
two grounds) then there will be no problem.

You should have a lead from your equipment to the RF ground and THEN
to the Mains ground (two paths, one conductor) in that order:

MAINSGROUND-------------RFGROUND------------SHACK GOOD
MAINSGROUND----------SHACK-----------RFGROUND BAD

By the way, I am using an older Kenwood TS530S (until I get some experience and
decide to invest in a more current rig). Are current rigs now always with three
pronged polarized/grounded plugs? My unit here has a two prong non-polarized ac
plug, just like the old audio tube amps I still use for hi-fi.

Most rigs aren't AC powered at all - they require 13.6VDC that comes
from an AC powered DC supply. AC power is floating with a
Hot/Neutral. Neutral eventually finds ground but you are in jeopardy
of relying on that. Ground, the third wire, is a safety consideration
and is never expected to conduct current except as a consequence of
failure. Modern construction practices and code certainly mandates a
thick enough conductor, but not for the purpose of supporting power
needs.

In 1953 when I was first a novice, I used a bizarre little homemade transmitter
with one 117N7 tube which only plugged into one side of the house current!!!!

This is also from an era when newspapers reported the passing of
husbands or wives who, while washing the dishes, leaning on the stove,
playing with the toaster, putting down the iron, turning off the
mixer, or holding the refrigerator door.... leaned over to turn down
the radio volume - classic across the heart scenario - classic
results.

They were killed by "modern" engineering design techniques to reduce
noise (caps across the mains to the metal frame). Let's see, is it
suppose to plug in this way, or was it the oth.*#!!**#.....

73's
Richard Clark, KB7QHC

I think this is starting to make sense, maybe. My RF ground rod which is directly
under the station about 6' directly down, also ties to a series of additional rods
about 10 feet apart in both directions from that first rod (I am thinking this is
like a radial since the bare wire connecting them is also on the earth (?). Should
I connect the furthest rod of this series to the house mains ground rod which is
actually not that far away at that point? Would I be ok then?

-bill




Richard Clark wrote:

On Sat, 17 Apr 2004 18:42:44 GMT, zeno wrote:

Hi Bill,

By the points offered:

Then I turn around, and experienced hams are telling me the exact opposite, eg.
not to tie the RF ground to the house AC safety ground.

Experienced Amateurs (as distinct from experienced Professionals).

To tie the RF ground to
the house safety ground rod means a much longer run and thus the potential
problems of 1/4 wavelength resonance also mentioned here.

The basic confusion that arises is in the distinction between RF and
Mains ground. You can keep your RF ground rod (add some radials to it
to actually make it RF ground) as long as you tie it to the Mains
ground (usually in close proximity to the drop and meter). The
distance between THESE two points is immaterial RF wise as your RF
ground will insure little or no RF current travels to the Mains
ground. In THIS sense, they are separate.

If there is noise (RF) on the Mains, it may seek your RF ground
through this connection, but as long as you are not sharing it (you
are not using this lead to both connect your equipment AND connect the
two grounds) then there will be no problem.

You should have a lead from your equipment to the RF ground and THEN
to the Mains ground (two paths, one conductor) in that order:

MAINSGROUND-------------RFGROUND------------SHACK GOOD
MAINSGROUND----------SHACK-----------RFGROUND BAD

By the way, I am using an older Kenwood TS530S (until I get some experience and
decide to invest in a more current rig). Are current rigs now always with three
pronged polarized/grounded plugs? My unit here has a two prong non-polarized ac
plug, just like the old audio tube amps I still use for hi-fi.

Most rigs aren't AC powered at all - they require 13.6VDC that comes
from an AC powered DC supply. AC power is floating with a
Hot/Neutral. Neutral eventually finds ground but you are in jeopardy
of relying on that. Ground, the third wire, is a safety consideration
and is never expected to conduct current except as a consequence of
failure. Modern construction practices and code certainly mandates a
thick enough conductor, but not for the purpose of supporting power
needs.

In 1953 when I was first a novice, I used a bizarre little homemade transmitter
with one 117N7 tube which only plugged into one side of the house current!!!!

This is also from an era when newspapers reported the passing of
husbands or wives who, while washing the dishes, leaning on the stove,
playing with the toaster, putting down the iron, turning off the
mixer, or holding the refrigerator door.... leaned over to turn down
the radio volume - classic across the heart scenario - classic
results.

They were killed by "modern" engineering design techniques to reduce
noise (caps across the mains to the metal frame). Let's see, is it
suppose to plug in this way, or was it the oth.*#!!**#.....

73's
Richard Clark, KB7QHC

Richard Clark wrote:


MAINSGROUND-------------RFGROUND------------SHACK GOOD
MAINSGROUND----------SHACK-----------RFGROUND BAD

I may still be confused here, not really fuly comprehending the above illustration.

The mainsground comes to the shack anyway in the AC outlets powering the shack,
being the third or ground terminal (although not really connecting to my Kenwood
530 which in this unique case only has a two prong AC plug and internal power
suppy.

I think this ground thing has to do with the "routing" as you indicate, just as the
mystery of ground loops in an old tube hi-fi amp where the correct star grounding
is the way to get rid of hum. As long as my shack RF ground is a short direct route
to the first ground rod of the series, I should be ok then tying the mains ground
to a "later" point in the RF ground rod system. (?)

bill

On Sat, 17 Apr 2004 20:15:21 GMT, zeno wrote:

I think this is starting to make sense, maybe. My RF ground rod which is directly
under the station about 6' directly down, also ties to a series of additional rods
about 10 feet apart in both directions from that first rod (I am thinking this is
like a radial since the bare wire connecting them is also on the earth (?).

Hi Bill,

The additional ground rods don't do much, RF-wise. You are far better
off with wire laid out radially on or just below the ground surface.
However, what you have is good.

Should I connect the furthest rod of this series to the house mains ground rod which is
actually not that far away at that point? Would I be ok then?

Depends on what you mean by furthest, but it sounds OK. Look at my
answer in the other post.

73's
Richard Clark, KB7QHC

On Sat, 17 Apr 2004 20:22:56 GMT, zeno wrote:
Richard Clark wrote:

MAINSGROUND-------------RFGROUND------------SHACK GOOD
MAINSGROUND----------SHACK-----------RFGROUND BAD

I may still be confused here, not really fuly comprehending the above illustration.

The mainsground comes to the shack anyway in the AC outlets powering the shack,
being the third or ground terminal (although not really connecting to my Kenwood
530 which in this unique case only has a two prong AC plug and internal power
suppy.

I think this ground thing has to do with the "routing" as you indicate, just as the
mystery of ground loops in an old tube hi-fi amp where the correct star grounding
is the way to get rid of hum. As long as my shack RF ground is a short direct route
to the first ground rod of the series, I should be ok then tying the mains ground
to a "later" point in the RF ground rod system. (?)

Hi Bill,

Look again at the illustration. Now think of noise originating in the
Mains and traveling towards RF ground. That current, across
impedance, produces noise voltage. In the "BAD" illustration, think
of the left hand as hot, and the right side as cold. Just like at a
setting of a potentiometer, noise voltage is injected INTO the SHACK
if there are other paths to ground (there always are, you describe
just exactly how it happens above).

Now, repeat the same problematic noise current in the "GOOD"
illustration. It sinks right into RFGROUND and does not proceed on
towards the SHACK.

You will of course have mixed grounds because this vale of tears we
call reality demands that you power your SHACK from the Mains. And if
it weren't that, it would be the 'puter, or the phone, or a battery
charger for the drill (the list is endless and so common that we
become blind to the obvious paths mixing noise into our life).

Most local noise is conductive. That is, it comes from the source and
the sink residing on the same breaker in the panel. The source noise
current injects itself into the sensitive sink side that is sharing
the path. By using an extension cord, you can confirm this by
powering the noise source off another outlet that goes to a different
breaker. That noise that is not conductive is radiative. It arrives
from the source through the air. This can be nipped in the bud by
using a transmission line choke at its entry (generally the feedpoint
of the antenna).

73's
Richard Clark, KB7QHC

Most local noise is conductive. That is, it comes from the source and
the sink residing on the same breaker in the panel. The source noise
current injects itself into the sensitive sink side that is sharing
the path. By using an extension cord, you can confirm this by
powering the noise source off another outlet that goes to a different
breaker. That noise that is not conductive is radiative. It arrives
from the source through the air. This can be nipped in the bud by
using a transmission line choke at its entry (generally the feedpoint
of the antenna).

73's
Richard Clark, KB7QHC

Is this true for all antenna designs? Is this choke various depending on other
characteristics of antenna and feedline.

For example, in my anticipated 160m full wave loop which I plan to feed with diy ladder
line to a Johnson Matchbox (250w), is there a specific recommendation for such a choke?
Can I simply make what I need with a few windings of something around another round
something and than wrapp it in rubber tape etc. Is this something I can incorporate
into the hardware system at the antenna feedpoint where I will be attaching the two
ends of my loop to the ladder line?

-bill

On Sun, 18 Apr 2004 02:48:58 GMT, zeno wrote:
Is this something I can incorporate
into the hardware system at the antenna feedpoint where I will be attaching the two
ends of my loop to the ladder line?

Hi Bill,

Feedline chokes are principally designed for the nature of coax which
is unbalanced by design. Ladder line is presumably balanced and thus
resists noise pickup of local origin. However, the balance is
strictly a matter of its load, and if either end of the line meets an
unbalance, the whole system is off balance and noise can intrude
through what is called "the common mode." As such, balance is a very
local thing that only you can determine through performance.

I imagine that a loop would be harder to unbalance; but dipoles,
especially low ones, are very susceptible.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

The additional ground rods don't do much, RF-wise. You are far better

off with wire laid out radially on or just below the ground surface.
However, what you have is good.

How long should those radials be? and would just a couple be better than none?

Bill