Has anyone had a "bad", as in less then stellar performance, with a
Wellbrook ALA 1530
loop antenna?

Given the almost sacred refference the Wellbrook is held in I have
debated asking
this question. I have a ALA 1530 that is part of a trade that I am
looking at and
guys I just don't get it. This antenna is reputed to be the cat's meow,
but I have
found it marginal at best. A north country active antenna is nearly
it's match
and the 3rd harmonic of a local MW (770KHz) is S3 on the Wellbrook. A
Lankford Active Dipole stomps it in gain, IP2 and IP3 and for
directivity.

I am wondering if this antenna is defective or if it is a case of the
Emperors New
Clothes. I have tried loops several times in the last 30 years and
always give up
becuase I have never found the reported imunity against local QRM to be
true.
I am building a copy of the WL1030 (http://wl1030.com/), but I don't
understand
the fascination with loops. What am I missing?

For MW DX "big" air loops make sense. Good directivity to null out an
offending
signal. I notice Ron Harding uses McKay 100E with a phaser to achieve
good
nulls. For HF the sky wave "smears" both the desired and unwanted
signals
making a null very iffy.

Receivers used in this test:
R2000
R8B
R390
R392
The R390 and R392 where not tested at my home but at a friend's home
where I have them stored. While I like both the R390 and R392, they are
somewhat awkward to rapidly tune from one frequency to a wildly
seperated
one.

Terry

In article .com,
wrote:

Has anyone had a "bad", as in less then stellar performance, with a
Wellbrook ALA 1530 loop antenna?

Given the almost sacred refference the Wellbrook is held in I have
debated asking this question. I have a ALA 1530 that is part of a
trade that I am looking at and guys I just don't get it. This antenna
is reputed to be the cat's meow, but I have found it marginal at
best. A north country active antenna is nearly it's match and the 3rd
harmonic of a local MW (770KHz) is S3 on the Wellbrook. A Lankford
Active Dipole stomps it in gain, IP2 and IP3 and for directivity.

I am wondering if this antenna is defective or if it is a case of the
Emperors New Clothes. I have tried loops several times in the last 30
years and always give up becuase I have never found the reported
imunity against local QRM to be true. I am building a copy of the
WL1030 (http://wl1030.com/), but I don't understand the fascination
with loops. What am I missing?

For MW DX "big" air loops make sense. Good directivity to null out an
offending signal. I notice Ron Harding uses McKay 100E with a phaser
to achieve good nulls. For HF the sky wave "smears" both the desired
and unwanted signals making a null very iffy.


Receivers used in this test:
R2000
R8B
R390
R392
The R390 and R392 where not tested at my home but at a friend's home
where I have them stored. While I like both the R390 and R392, they
are somewhat awkward to rapidly tune from one frequency to a wildly
seperated one.

I don't know what to tell you about your experience with loop antennas.
My experience and many others is contrary to yours. Loop antennas are
not a fascination just a good design. I've never used the Wellbrook
antennas so I don't know the construction details. Maybe the antenna is
not constructed properly.

Your complaint about IP2 and IP3 concerns the amplifier design not the
antenna design.

--
Telamon
Ventura, California

wrote:
Has anyone had a "bad", as in less then stellar performance, with a
Wellbrook ALA 1530
loop antenna?

Given the almost sacred refference the Wellbrook is held in I have
debated asking
this question. I have a ALA 1530 that is part of a trade that I am
looking at and
guys I just don't get it. This antenna is reputed to be the cat's meow,
but I have
found it marginal at best. A north country active antenna is nearly
it's match
and the 3rd harmonic of a local MW (770KHz) is S3 on the Wellbrook. A
Lankford Active Dipole stomps it in gain, IP2 and IP3 and for
directivity.

I am wondering if this antenna is defective or if it is a case of the
Emperors New
Clothes. I have tried loops several times in the last 30 years and
always give up
becuase I have never found the reported imunity against local QRM to be
true.
I am building a copy of the WL1030 (http://wl1030.com/), but I don't
understand
the fascination with loops. What am I missing?

For MW DX "big" air loops make sense. Good directivity to null out an
offending
signal. I notice Ron Harding uses McKay 100E with a phaser to achieve
good
nulls. For HF the sky wave "smears" both the desired and unwanted
signals
making a null very iffy.

Receivers used in this test:
R2000
R8B
R390
R392
The R390 and R392 where not tested at my home but at a friend's home
where I have them stored. While I like both the R390 and R392, they are
somewhat awkward to rapidly tune from one frequency to a wildly
seperated
one.

Terry

One thing you might do is check the cables connecting the different
components of the Wellbrook. At one point I noticed that my loop wasn't
performing as I thought it should and I discovered that the cable
connecting the receiver to the antenna interface had a poor connection
where it meets the interface box. The intermittent connection became
obvious as soon as I jiggled the cable a bit.

Also, where do you have the loop situated? In my experience the
performance of the loop is seriously degraded when used indoors.

Steve wrote:


One thing you might do is check the cables connecting the different
components of the Wellbrook. At one point I noticed that my loop wasn't
performing as I thought it should and I discovered that the cable
connecting the receiver to the antenna interface had a poor connection
where it meets the interface box. The intermittent connection became
obvious as soon as I jiggled the cable a bit.

Also, where do you have the loop situated? In my experience the
performance of the loop is seriously degraded when used indoors.

Calbe and connectors are good, and have been used to power
the Lankford active dipole I am checking.

I have tried it in a variety of locations.

We even went so far as to drive to the Red River Gorge, an area well
away
from houses, power lines etc.

The preformance just doesn't strike me as being worth the fairly high
cost.

The active dipole beat it every time.

Terry

In article om,
wrote:

Steve wrote:


One thing you might do is check the cables connecting the different
components of the Wellbrook. At one point I noticed that my loop
wasn't performing as I thought it should and I discovered that the
cable connecting the receiver to the antenna interface had a poor
connection where it meets the interface box. The intermittent
connection became obvious as soon as I jiggled the cable a bit.

Also, where do you have the loop situated? In my experience the
performance of the loop is seriously degraded when used indoors.

Calbe and connectors are good, and have been used to power the
Lankford active dipole I am checking.

I have tried it in a variety of locations.

We even went so far as to drive to the Red River Gorge, an area well
away from houses, power lines etc.

The preformance just doesn't strike me as being worth the fairly high
cost.

The active dipole beat it every time.

That was a self defeating test. The idea here is that you will have a
lower noise floor in a locally noisy area with a shielded loop than a
dipole antenna. There is going to be no advantage to using a loop over
a dipole in an electrically quiet area.

A shielded loop is not better at picking up a distant signal than a
dipole but is less sensitive to local noise generators so in an area
with high local noise you would have better signal to noise than a
full size dipole antenna.

I also expect that a shielded loop would be better than a amplified
electrically small dipole although the difference in advantage would be
smaller than the comparison to a full sized dipole. Depending on the
area a electrically small dipole and shielded loop may not have a
significant difference in local noise floor because you managed to get
both far enough from local noise makers due to their small size.

If you found a problem connection from interface to antenna then I
would suspect your findings. As you well know that connection is the
power supply to the antenna amplifier and the RF path back to the
radio.

"The active dipole beat it every time" is a bit vague. Maybe you could
expand a little on that.

--
Telamon
Ventura, California

" That was a self defeating test. The idea here is that you will have a
lower noise floor in a locally noisy area with a shielded loop than a
dipole antenna. There is going to be no advantage to using a loop over
a dipole in an electrically quiet area.

A shielded loop is not better at picking up a distant signal than a
dipole but is less sensitive to local noise generators so in an area
with high local noise you would have better signal to noise than a
full size dipole antenna.

Please see:
http://www.w8ji.com/magnetic_receiving_loops.htm

Dale W4OP

In article kImTg.111$pS3.23@trnddc01,
"Dale Parfitt" wrote:

" That was a self defeating test. The idea here is that you will have a
lower noise floor in a locally noisy area with a shielded loop than a
dipole antenna. There is going to be no advantage to using a loop over
a dipole in an electrically quiet area.

A shielded loop is not better at picking up a distant signal than a
dipole but is less sensitive to local noise generators so in an area
with high local noise you would have better signal to noise than a
full size dipole antenna.

Please see:
http://www.w8ji.com/magnetic_receiving_loops.htm

A nice page written by some amateur drawing wrong conclusions. Following
his logic coax cable would not shield the center conductor either for
example since the coax has to be open on both ends. He quotes a lot of
good information and then spouts conclusion that don't follow.

I don't have the patience to read the whole page but I scanned through
it and for starters he does not seem to distinguish between far and near
field energy. Far field has equal energy in the E and H fields so two
antennas, example dipole and loop, that are strongly couple to one field
and not the other generate the same power. No real difference then
between antennas that are strongly affected by one field and not the
other to far field signal or noise.

Near field is a different story. Near field is what the local noise
makers generate the most of and the electric tends to propagate farther
than the magnetic from the source so you want to use an antenna that is
sensitive to the H field for the same reason you try to get an antenna
as far away from local noise sources as possible. You can see the logic
in that right?

And let's not forget about that very handy null in the loop pattern. I
use that all the time on the AM portable with its built in loop stick
antenna that is not even shielded.

--
Telamon
Ventura, California

Dale Parfitt wrote:
" That was a self defeating test. The idea here is that you will have a
lower noise floor in a locally noisy area with a shielded loop than a
dipole antenna. There is going to be no advantage to using a loop over
a dipole in an electrically quiet area.

A shielded loop is not better at picking up a distant signal than a
dipole but is less sensitive to local noise generators so in an area
with high local noise you would have better signal to noise than a
full size dipole antenna.

Please see:
http://www.w8ji.com/magnetic_receiving_loops.htm

Dale W4OP

Dale [W4OP] - Thanks for the very informative link.
http://www.w8ji.com/magnetic_receiving_loops.htm

Magnetic Loop Antennas Receiving
"Small Receiving Loop Antennas"
http://www.w8ji.com/magnetic_receiving_loops.htm

* Small Loop Antennas are often referred to as "Magnetic Radiators".
Folklore claims a small "Shielded" Loop Antenna behaves like a
sieve, sorting "good magnetic signals" from "bad electrical noise".
http://www.w8ji.com/magnetic_receiving_loops.htm

* Nothing is further from the truth! At relatively small distances a
small Magnetic Loop Antenna is more sensitive to Electric Fields
than a small Electric Field Probe type Antenna.
http://www.w8ji.com/magnetic_receiving_loops.htm

* Field Impedance of the Loop Antenna
http://www.w8ji.com/magnetic_receiving_loops.htm
Loop Antenna Fields - Short Dipole or Vertical Fields - Radiation

* Loop Antenna Shielding and Balance
http://www.w8ji.com/magnetic_receiving_loops.htm

* Examples of Small Loop Antennas
and Analysis of Loop Antenna Construction
http://www.w8ji.com/magnetic_receiving_loops.htm

* Typical Magnetic Loop Antenna
(found on Internet and other places)
http://www.w8ji.com/magnetic_receiving_loops.htm

* Circuit Representations of Shielded Loop Antennas
http://www.w8ji.com/magnetic_receiving_loops.htm

Has anyone had a "bad", as in less then stellar performance, with a
Wellbrook ALA 1530
loop antenna?

Hi Terry,

I have a homebrew version of the Wellbrook shielded loop 7' in diameter. It
is in my woods on a short tower and rotator.
On 160M and 75M it is the same as my 80M inverted vee. It's a good performer
on MW/LW but not any real difference between it and a homebrew voltage probe
antenna with a 4' whip.

Loops are most useful where there is a single noise source that can be
nulled with the loop- other than that, it's a toss up.
There is still the wive's tale making the rounds that shielded loop are
immune to the E field noise - rubbish and well disproven in the literature.

So, in summary, I like mine for being a compact RX antenna for MW/LW, but at
least in my environment, not sure I would go to the trouble next time.

Dale W4OP
for PAR Electronics, Inc.

Dale Parfitt wrote:
Has anyone had a "bad", as in less then stellar performance, with a
Wellbrook ALA 1530
loop antenna?

Hi Terry,

I have a homebrew version of the Wellbrook shielded loop 7' in diameter. It
is in my woods on a short tower and rotator.
On 160M and 75M it is the same as my 80M inverted vee. It's a good performer
on MW/LW but not any real difference between it and a homebrew voltage probe
antenna with a 4' whip.

Loops are most useful where there is a single noise source that can be
nulled with the loop- other than that, it's a toss up.
There is still the wive's tale making the rounds that shielded loop are
immune to the E field noise - rubbish and well disproven in the literature.

So, in summary, I like mine for being a compact RX antenna for MW/LW, but at
least in my environment, not sure I would go to the trouble next time.

Dale W4OP
for PAR Electronics, Inc.

I am begining to think that many people over rate a loop because it has
lower over
all gain and therefore is quiter. Based on my experience with improved
detector and
audio chains I have come to understand that the signal to noise is the
only variable
that really matters. I wish my fancy HiFer beacon/test source had not
been fried
by Thor. Even the 13.xxMHz crsytal was toast! It would be interesting
to run some
real experiments to compare antennas the way I compared detectors and
post detection amplifiers.

BTW I have completly ripped out all of my coax and pulled down my
antennas.
Since I got rid of my desktop PC and I have gone to a laptop I found I
really needed
to redesign my radio desk. Since my antennas and coax have been up for
over 15
years, I decided to redo the whole mess.

Fall is a very good time to errect new antennas and I am going to
reroute all my coax
through 1/2" copper tubing that will be bonded to my perimeter ground
ring. An
electrician friend used his mini Ditch Witch to dig me a couple of
trenches. I hope
to have the antennas back up by Monday evening.

I typically research and build devcies in the summer, think about
antennas in teh
fall and do serious listening over the winter.

Terry