My neighborhood is loaded with some kind of electrical noise which makes
working 160 & 75 meters difficult. I have tried to locate the source but
have come up empty at this point. It appears to be something other than
power line noise which may mean its coming from someones house.

I was hoping the solution to the problem was to build a low noise receiving
loop antenna.

Well, the noise is mostly gone..........but so are the signals.....even when
I use a preamp.

I have tried an ICE 75 meter preamp and a KD9SV 160/75 meter preamp.

Still the noise is gone but the signals are really weak, if I hear anything
at all.

Not sure what if anything I did is wrong or if I am expecting too much from
this loop or the preamps don't have enough gain to make this work.

Anyone familiar enough with receiving loops to be able to assist me in
figuring out whats wrong here?

TIA

Tony

On Sat, 17 Nov 2007 07:36:28 -1000, Tony Giacometti
wrote:

Anyone familiar enough with receiving loops to be able to assist me in
figuring out whats wrong here?

Hi Tony,

There is no such thing as a Low Noise antenna (loop or otherwise).

Given that what you build is deaf, that should be a reality check of
this presumed quality of the antenna.

Well, actually, you built it wrong. However, building it right stands
only a partial chance of lowering noise, and not because the antenna
has some remarkable quality that is not otherwise found in the plug
ordinary dipole. In that sense, the reduction of noise would only
follow turning the dipole (or loop, same thing) until the source of
that noise fell into a null. This is the conventional method of
employing a "Low Noise" antenna.

Let me guess. It is a shielded loop. You forgot to leave a gap in
the shield.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Sat, 17 Nov 2007 07:36:28 -1000, Tony Giacometti
wrote:

Anyone familiar enough with receiving loops to be able to assist me in
figuring out whats wrong here?

Hi Tony,

There is no such thing as a Low Noise antenna (loop or otherwise).

Given that what you build is deaf, that should be a reality check of
this presumed quality of the antenna.

Well, actually, you built it wrong. However, building it right stands
only a partial chance of lowering noise, and not because the antenna
has some remarkable quality that is not otherwise found in the plug
ordinary dipole. In that sense, the reduction of noise would only
follow turning the dipole (or loop, same thing) until the source of
that noise fell into a null. This is the conventional method of
employing a "Low Noise" antenna.

Let me guess. It is a shielded loop. You forgot to leave a gap in
the shield.

73's
Richard Clark, KB7QHC

it is a shielded loop and no the gap is there, thats why I am wondering why
its not doing what I thought it would do.

On Sat, 17 Nov 2007 09:07:58 -1000, Tony Giacometti
wrote:

Let me guess. It is a shielded loop. You forgot to leave a gap in
the shield.

it is a shielded loop and no the gap is there, thats why I am wondering why
its not doing what I thought it would do.

Hi Tony,

It is working perfectly! It is working exactly as it was constructed.

You got your plans from the wrong source (or misread them, or failed
to follow directions).

There are several ways to construct one correctly, so I won't go into
those variations. There is probably a fix to the one you have, but
that is shooting in the dark.

Let's simply investigate the quality you seek. Low Noise comes only
from the antenna's quality of yielding the best dipole performance
possible under the circumstances. As these circumstances often
involve use in the low frequencies, the traditional high elevation
long-wire dipole is usually not an option. Further, if it is, it
rarely allows for rotation. What is usually within the user's skill
or available space renders a dipole that suffers from the proximity of
"things." These "things" disrupt the balance, and hence the
directionality of the dipole; thus noise sensitivity rises (noise
fills in through what should have been nulls in the dipole pattern).
The user still cannot turn the dipole and thus the long-wire in the
garden is a mediocre performer at best, and is usually a
disappointment all around.

Enter the loop.

The traditional loop for low frequency use is in fact quite small. By
being small it suffers less in relation to the proximity of "things."
This, of course, is if you erect it in the same place as that
long-wire disappointment you tugged down. That is, the loop improves
only in comparison; fortunately, it also brings the virtue of being
rotatable. That would be enough, but the snake oil salesmen like to
guild the Lily.

Enter the shielded loop.

The shielded loop solves a problem, certainly. That is the problem of
balance. However, if you use careful crafting of a simple loop, you
don't have any problem to solve.

There are many other details to sort out. That can be left to other
correspondence.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Sat, 17 Nov 2007 09:07:58 -1000, Tony Giacometti
wrote:

Let me guess. It is a shielded loop. You forgot to leave a gap in
the shield.

it is a shielded loop and no the gap is there, thats why I am wondering
why its not doing what I thought it would do.

Hi Tony,

It is working perfectly! It is working exactly as it was constructed.

You got your plans from the wrong source (or misread them, or failed
to follow directions).

There are several ways to construct one correctly, so I won't go into
those variations. There is probably a fix to the one you have, but
that is shooting in the dark.

Let's simply investigate the quality you seek. Low Noise comes only
from the antenna's quality of yielding the best dipole performance
possible under the circumstances. As these circumstances often
involve use in the low frequencies, the traditional high elevation
long-wire dipole is usually not an option. Further, if it is, it
rarely allows for rotation. What is usually within the user's skill
or available space renders a dipole that suffers from the proximity of
"things." These "things" disrupt the balance, and hence the
directionality of the dipole; thus noise sensitivity rises (noise
fills in through what should have been nulls in the dipole pattern).
The user still cannot turn the dipole and thus the long-wire in the
garden is a mediocre performer at best, and is usually a
disappointment all around.

Enter the loop.

The traditional loop for low frequency use is in fact quite small. By
being small it suffers less in relation to the proximity of "things."
This, of course, is if you erect it in the same place as that
long-wire disappointment you tugged down. That is, the loop improves
only in comparison; fortunately, it also brings the virtue of being
rotatable. That would be enough, but the snake oil salesmen like to
guild the Lily.

Enter the shielded loop.

The shielded loop solves a problem, certainly. That is the problem of
balance. However, if you use careful crafting of a simple loop, you
don't have any problem to solve.

There are many other details to sort out. That can be left to other
correspondence.

73's
Richard Clark, KB7QHC



Richard, I use a vertical antenna, for transmitting its great, does a fine
job, but for receive, with the noise in the neighborhood, its not the best
option. I have tried to use an ANC-4 noise reducer but the noise isn't
reduced enough to hear the weaker signals.

So, what to do, I followed the instructions for building the loop from W2YR
and KN4LF and from this link
http://www.hard-core-dx.com/nordicdx.../coaxloop.html

As I wrote previous I have 2 good preamps but the signals are still very
weak.

Have you ever built one of these?

If so, did you experience the same problem?

I don't have room for a beverage but if I am unable to solve this loop issue
I will probably have to consider a K9AY array which will force me to move
other antennas around on my 1/3rd of an acre.

On Sat, 17 Nov 2007 10:30:06 -1000, Tony Giacometti
wrote:

Richard, I use a vertical antenna, for transmitting its great, does a fine
job, but for receive, with the noise in the neighborhood, its not the best
option. I have tried to use an ANC-4 noise reducer but the noise isn't
reduced enough to hear the weaker signals.

Hi Tony,

Leaving that aside for others to comment....

So, what to do, I followed the instructions for building the loop from W2YR
and KN4LF and from this link
http://www.hard-core-dx.com/nordicdx.../coaxloop.html

There is a world of opportunity in making a mistake with this monster.
It goes a long way to do something difficult that could be done vastly
easier.

As I wrote previous I have 2 good preamps but the signals are still very
weak.

You state that there is no gap. The page you supply clearly shows
gaps at the top of the two loops. Anything you hear is a function of
the poor shielding. By your description of your construction, you
shouldn't be able to hear anything at all!

Have you ever built one of these?

No, not one of these (there are too many frogs to kiss them all).

I don't have room for a beverage but if I am unable to solve this loop issue
I will probably have to consider a K9AY array which will force me to move
other antennas around on my 1/3rd of an acre.

A solution is vastly simpler than that - and you can still build a
loop. Google for more designs and submit them here for review (the
one you provided rates low on the sanity scale).

73's
Richard Clark, KB7QHC

Tony Giacometti wrote in
news:VvSdnQC_g_Sb0qLanZ2dnUVZ_hKdnZ2d@hawaiiantel. net:

So, what to do, I followed the instructions for building the loop from
W2YR and KN4LF and from this link
http://www.hard-core-dx.com/nordicdx.../coaxloop.html

I think you are describing a scenario where, with the loop+preamp, the
receiver system is limited by internal noise rather than external noise.

So, it is a two band design, and that complicates matters somewhat.

Just concentrating on the 160m loop...

My calcs are that the 160m loop alone, tuned for zero series reactance
(should need ~90pF) and loaded with 50 ohms should have equivalent gain
of around -47dBi.

You would have to consider the preamp NF and gain and receiver NF to
evaluate the system noise floor, and you haven't given those details
(though they may be implied... but I am not familiar with the preamp you
are using).

Without using a preamp, the external noise (based on ITU-R P.372-8
Residiential man made noise) with this loop ought be of about the same
magnitude as the internal noise of a good transceiver, give or take. For
a preamp to improve the situation, it would need a NF significantly
better than the transceiver and sufficient gain to overcome the
transceiver noise.

Owen

Tony Giacometti wrote:

it is a shielded loop and no the gap is there, thats why I am wondering why
its not doing what I thought it would do.

What you've done is to build a truly shielded loop. The notion that a
shield somehow blocks the electric field and lets the magnetic field
through is a folk tale -- an intact shield like the one you built blocks
both electric and magnetic fields. (Good thing, too, or else coax cable
wouldn't do its job.) You've just done an experiment that proves it.

The gap in a so-called "shielded loop" provides a path for current
outside the "shield" to get inside. The net result is that the outside
of the "shield" is just an ordinary loop antenna, and the gap acts like
a feedpoint to get the current inside where it can get to the receiver.
It responds to normal electric and magnetic fields exactly like an
unshielded loop. What the "shield" buys you is improved balance, which
helps prevent the feedline from becoming part of the antenna and picking
up local noise which you can null out if balance is good.

Roy Lewallen, W7EL

Richard Clark wrote:

On Sat, 17 Nov 2007 10:30:06 -1000, Tony Giacometti
wrote:

Richard, I use a vertical antenna, for transmitting its great, does a fine
job, but for receive, with the noise in the neighborhood, its not the best
option. I have tried to use an ANC-4 noise reducer but the noise isn't
reduced enough to hear the weaker signals.

Hi Tony,

Leaving that aside for others to comment....

So, what to do, I followed the instructions for building the loop from
W2YR and KN4LF and from this link
http://www.hard-core-dx.com/nordicdx.../coaxloop.html

There is a world of opportunity in making a mistake with this monster.
It goes a long way to do something difficult that could be done vastly
easier.

As I wrote previous I have 2 good preamps but the signals are still very
weak.

You state that there is no gap.

sorry, but maybe I wasn't clear enough, there IS a gap - just like the one
in the link.


The page you supply clearly shows
gaps at the top of the two loops. Anything you hear is a function of
the poor shielding. By your description of your construction, you
shouldn't be able to hear anything at all!

Have you ever built one of these?

No, not one of these (there are too many frogs to kiss them all).

I don't have room for a beverage but if I am unable to solve this loop
issue I will probably have to consider a K9AY array which will force me to
move other antennas around on my 1/3rd of an acre.

A solution is vastly simpler than that - and you can still build a
loop. Google for more designs and submit them here for review (the
one you provided rates low on the sanity scale).

I did do a search for loops of this type and basically they are all the
same.

I have been told Wellbrook makes good loops, but I don't like the idea of
spending $300-$500 for one at this point.


73's
Richard Clark, KB7QHC

Roy Lewallen wrote in
:

Tony Giacometti wrote:

it is a shielded loop and no the gap is there, thats why I am
wondering why its not doing what I thought it would do.

What you've done is to build a truly shielded loop. The notion that a

I think you guys are reading this the wrong way. Perhaps it should have
been written "it is a shielded loop and no, the gap is there,..."

You know people asking questions don't take much care in expression.

Owen