wrote in
:

Telamon,it took me ten years to scroll down to what you were saying.You
need to work on that.
cuhulin


You either got a lazy scroll finger, or your digi-talker doesn't talk
fast.

SC

In article . com,
wrote:

Telamon wrote:
In article . com,
wrote:

Telamon wrote:
In article
. com,
wrote:

Telamon wrote:
In article
. com,
wrote:

Telamon wrote:
In article
.com,
"R390A" wrote:


Telamon wrote:
In article
.c
om,
"R390A" wrote:

To Whom It May Concern: Additions and revisions
have been made to two of my articles about
vertical antennas and the ALA 100 on the
www.kongsfjord.com web site. The articles are
(1) "Measurements Of Some Antennas Signal To Man
Made Noise Ratios In The Daytime MW And LW
Bands," and (2) "Some Of My Favorite Small
Antennas For MW And LW." In the first article an
additional comparison of the ALA 100 was made
with an active whip antenna. The ALA 100 and
active whip had about the same signal to man made
noise ratio. In the second article some
information was added about reducing noise in
active whip antennas due to what are believed to
be ground loops in the DC feed.

The link is dead.
http://www.kongsfjord.no/dl/Antennas/Measurements%2
0Of%20So me%2 0Antenna s
%20Signal%20To%20Man%20Made%20Noise%20Ratio.pdf


Try www.kongsfjord.no and then click on The Dallas
Files.

That link worked.

Looking at your data I'm at a disadvantage not knowing
which are radio stations and which are computer noise
other than KNOE 540 kHz you specifically pointed out.
Another problem for me is the loop antenna gain looks
to be about 10 dB less than the other antennas. While
actually not a problem for signal to noise measurements
it does make the sweep look different to a person that
did not make the measurement.

Antennas in different locations around your house is
not exactly apples to apples comparison.

If your spectrum analyzer has a max hold on the trace
that would be a help in measuring the top of the noise
floor.

A clear difference in S/N would be the last pair on
page three 1500 to 2000 KHz where the ALA-100 looks to
be 22 dB (-42 S to -60 N) compared to the vertical 33
dB (-32 S to -65 N). One problem for me here is I don't
know what the analyzer noise floor itself is at this
point and I can see that the loop has 10 dB less gain
than the other antennas. Assuming that the analyzer
noise floor is -70 dBm and lower would make this
comparison valid. A simple check of just disconnecting
the cable from the analyzer at those settings would
show the instrument noise floor. Using max hold would
make the noise floor less ambiguous.

Due to my disadvantages noted I can't draw any firm
conclusions based on the analyzer pictures.

I'm an audio person, but noise should be measured in
terms of root hertz. Thus the noise floor you see is a
function of the bandwidth of the tracking filter. As you
go narrower, the noise floor should drop.


*************

I have to take exception to the wording you ascribe to
other people such as myself about a "belief in magnetic
field sensitive antennas". I rely on belief only when I
have no other choice as a fall back to no being able to
test a thesis empirically.

An electrically small shielded loop antenna will
respond very poorly to a local electric induction field
and very well to a magnetic one. An electrically small
dipole would be just the opposite in response to
induction fields. This is theoretically and empirically
correct. I have much experience using these types of
antennas monitoring for induction fields and they
behaved as theory predicted.

When poorly designed electronic devices generate
induction fields the electric fields have the tendency
to spread farther from the source than the magnetic
fields. This is a generalization but knowing this leads
to the conclusion that a loop would pick up less of the
locally generated noise most of the time or in other
words it would be an advantage to use over a dipole.

Most people that have local noise problems and purchase
a loop antenna such as the Wellbrook find that their
listening situation is greatly improved.

I use a non-amplified folded dipole and non-amplified
shielded loop. The loop picks up much less of the local
noise and picks up as much signal as the folded dipole
depending on the band.

Notice that belief is not required for any of the
foregoing.

************

You have the right idea about field impedance vs
distance but that relationship is appropriate for
transmitting antennas that are efficient. Here the
subject is inefficient noise sources. Here the
induction fields fall off rapidly compared to an
efficient antenna.

*************

I just noticed that your ALA 100 is pretty big and not
electrically small at SW frequencies. This means it
will also respond to electric fields and being
broadband will raise the noise floor. Your 60 foot
amplified loop is 10 feet bigger than my passive loop.
Why do you need an amplifier with a 60 foot loop?
Normally when I consider an amplified loop it more like
1 to 3 foot in diameter.

Here again, I believe being broadband increases the
integrated noise, but not necessarily the noise measured
per root Hz. The final bandwidth of the filter of the
radio determines the integrated noise.

Say the noise was 1nV/root Hz. Say the filter bandwidth
was 6Khz. Multiply the square root of 6Khz times 1nV/Root
Hz to get 77.5nV.

That's why even if I know the model number of the spectrum
analyzer I can not easily know the instrument noise floor
in the sweep. The sweep settings will modify the noise
floor.

I took another look at the measurement pdf and I think it
likely that the analyzer noise floor at those settings is
lower than the measurement noise in the sweeps and so at
least in the last pair of comparison photos on page 3
clearly show that the ALA-100 has a poorer signal to noise
than the vertical he is comparing it with.

I still don't know about the other sweeps as I don't know
what is a radio station and what is the local noise in the
sweep. When I did work on a range I would turn the DUT on
and off to see what actually popped up on the sweep when
the DUT is turned on. You had to do this on a range where
you can't have a large enough screen room due to cost. I'm
sure the author knows what is being generated by the stuff
in his house and what is a radio station.

It looks to me that although the Wellbrook amplifiers have
very good intermodulation numbers but that the noise floor
may be high. You would have to put in a larger signal into
the Wellbrook to measure the intermodulation products
relative to the other antenna amplifiers in the pdf
document.

Wellbrook does not appear to give a noise figure for the
amplifier. The author of the pdf could easily make that
measurement since he has an analyzer. Maybe noise is coming
in through the power supply connection for the amplifier,
the amplifier has a poor noise floor, or the antenna is
picking it up.


The difficulty in making measurements on the ALA 100 with
test instruments is you need a differential drive. I don't
know if grounding one side is kosher.

Grounding one side would not be acceptable. I would use a
simple test BALUN to drive the input.

-- Telamon Ventura, California

Yeah, but then what are you testing. The ALA 100 or the balun.
Good instrumentation isn't simple.

The BALUN would be simple and you would test it first. It would be
no problem at all.

-- Telamon Ventura, California

Not really. You need the balun to "act" like the wire antenna, which
means you need to characterize the wire antenna first, so you know
the impedance you need for each frequency tested.

There is a reason why Welbrook has no competition. I wish they did
since that would lower the price of the gear. I'm sure ANdy Ikin is
just snickering at this thread.

No you do not want the BALUN to "act" like the antenna wire. The BALUN
is to couple the generators single ended output to the differential
amplifier input so the amplifier can be tested. This is trivial thing to
do to test the amplifier. I'm not going to argue about this.

Amplified loop outdoor antennas have a number of costs associated with
them and I don't expect prices to lower.

--
Telamon
Ventura, California

My webtv hand held remote control thangy and my webtv keyboard thangy
has two (count em,two) scroll functions.Slow and Fast.My webtv scrolls
can scroll up and down just as fast (maybe even Faster) as your puter
can.
cuhulin

I can leave you sittin at the Post.
cuhulin

Guy Atkins wrote:
Hi Dallas,

I've been curious about your noise-reducing antennas some time, so this past
weekend I decided to build one as accurately as possible per your design. I
first got interested these antennas in the early 1990s during some e-mail
exchanges with Denzil Wraight in Germany.

I used the 3:1 turns ratio in the antenna transformer, and 18 ga. twinlead
speakerwire between it and the 1:1 transformer. The top of the 45 ft.
vertical is suspended to a branch in a tall tree, and the bottom end
fastened to a 5-ft. copper pipe in the ground. The antenna is located about
60 feet from the house, and my Wellbrook ALA 100 is 40 feet from the house.

I was quite surprised find not just worse noise from the vertical, but MUCH
worse noise. Signal levels seem good, but the noise is so bad the
readability suffers greatly, compared to the loop. For instance, this
morning past sunrise I was hearing JOAK in Tokyo on 594 kHz with an S-3
signal in Japanese, coming in nicely on the loop. However, the same
frequency on the vertical was just a strong BUZZZZZ of light-dimmer type
QRM. This was the most pronounced of the comparisons, but in most cases of
checking frequencies up through HF, the loop was the outright winner. I
tried to record 594 khz for comparisons, but I was using my modded R-75 and
didn't have the recording software configured properly since my last
DXpedition, and my SDR-1000 isn't fully hooked up at the moment. So, I
wasn't able to make a quick recording before the signal faded with
increasing daylight.

I did find a couple signals on the tropical bands where the vertical
provided a stronger signal with equal noise pickup (so therefore better S/N
than the loop).

However, my main interest right now is foreign MW signals. Do you have any
tips for improving this antenna's noise rejection on MW?

I can only think of two things that might impact the performance here. I
used the same type of binocular core ferrites that W8JI recommends, as I
have a lot of them. You used a traditional torroid form. Also, I don't know
how good the ground needs to be for this antenna to work well; the single
5-ft pipe may not be sufficient (soil here is reasonably good, though, clay
mixed with organic material...it's a forest floor).

Thanks in advance for any ideas!

Guy Atkins
Puyallup, WA
www.sdr-1000.blogspot.com

I have found that a single ground point,ie "standard" 8' AC mains
ground ro, are
at best very marginal. And the lower the frequency, as a general rule,
the "bigger"
the ground should be. Hams often use radials.

Think of the classic dipole. It has two arms. The classic vertical
"monopole"
needs a very good, ie low RF resistance, grounds. At the very least I
would
try for a set of 3 6' ground rods seperated from each other by at least
6'.

I think I may have gone overboard with a whole house perimeter ground
ring,
but I was given the copper tubing and a friend used a small Ditch Witch
to
dig the trench.

Did the improved ground make a difference over the discribed set of 3
rods?
There is a 10W TIS station in Winchester that I couldn't receive on my
70'
"long" wire antenna with a R2000. I tried a, as near as I could build
it, identical
ground set up and wire antenna at about the same height, from a
friend's
home who is about 5 miles closer and who has a lower RF background
noise floor and I think I could detect the carrier in SSB.

Maybe your soil is unusualy conductive and a 5' rod will suffice, but I
suspect
that a better, ie more complete, ground system will help all of your
non
dipole antennas.

And exception to the "good" set of 3 ground rod "rule" is with the
Lankford
Active Antenna, AKA AMRAD, which will operate very nicely on a single
8' ground rod driven so that 2' remain above ground for a mounting
base.

With a Lankford Active Dipole no ground is required. I have tried one
with
and without the 6'/2' ground rod. And it worked very well both ways. At
some frequencies the grounded operation was a little quiter. Of course
with
any active antenna great care should be taken to insure that common
noise
mode noise doesn't go up the braid and enter the antenna. The Dipole
configeration is much less sensitive to common mode, but it attention
to
detail will be rewarded. The best single refference I have found is the
"Common Mode Choke" PDF by W1HIS. I don't have the link handy,
but I have given the link several times.

A call to your local utility and/or a MW broadcaster can often get you
valid
information on local ground conductivity conditions. I did notice that
on the
coldest days last winter, when the temp droped to below 0F, where my
older
ground lost some effficeincy from the ground freezing, my new, super
ground never varried. And this summer during the drier, though to be
fair this
was hardly a dry summer, periods my ground stayed effective.

I am not really into NDB or MW DX but I can report that the improved
ground
really made a lot more NDBs receivable, and I found a lot more garbage
stations on MW. A simpler super ground that we installed for Will, a
new
SWL that I am helping, consisted of a 1/4" copper tube that is about
20'
long and connects his "SW" ground to the AC/Mains/Telco/SatDish ground.
Lowered his noise by several S-units on a DX398 all across LW/MW and
lower
SW bands. He used a funky flat shovel to open a slot about 6" deep. I
would
have prefered deeper, but it was his home, copper and effort.

Terry

Hi Terry,

I tried a 4-foot ground rod because that's what Dallas showed in the antenna
diagram for his article. I do see now that his older article (which he
reproduces as an addendum to the newer version) shows and describes an
8-foot ground rod, however.

I have a Bentonite-enhanced ground rod about 12 feet away from the 4-footer.
I previously to use it for grounding the shield of a EWE antenna feedline,
but it's not currently in use, so I might run a heavy wire to that one and
give it a try. It's a good ground, and I've always had success with
Bentonite enhancement. It's such a hassle to dig the larger hole to hold all
the powdered Bentonite and water slurry, but the results can be worth the
effort.

In Seattle I've bought 50 lbs. of Bentonite for for just $13, but that was a
few years ago. I used to get all I wanted for free, as my wife's home town
in Wyoming has a number of Bentonite processing plants in the area. They
would give away slightly ripped bags of the stuff to anyone crazy enough to
ask for it!

Guy


wrote in message
ups.com...
I have found that a single ground point,ie "standard" 8' AC mains
ground ro, are
at best very marginal. And the lower the frequency, as a general rule,
the "bigger"
the ground should be. Hams often use radials.
SNIP
Terry

Guy Atkins wrote:
Hi Terry,

I tried a 4-foot ground rod because that's what Dallas showed in the antenna
diagram for his article. I do see now that his older article (which he
reproduces as an addendum to the newer version) shows and describes an
8-foot ground rod, however.

I have a Bentonite-enhanced ground rod about 12 feet away from the 4-footer.
I previously to use it for grounding the shield of a EWE antenna feedline,
but it's not currently in use, so I might run a heavy wire to that one and
give it a try. It's a good ground, and I've always had success with
Bentonite enhancement. It's such a hassle to dig the larger hole to hold all
the powdered Bentonite and water slurry, but the results can be worth the
effort.

In Seattle I've bought 50 lbs. of Bentonite for for just $13, but that was a
few years ago. I used to get all I wanted for free, as my wife's home town
in Wyoming has a number of Bentonite processing plants in the area. They
would give away slightly ripped bags of the stuff to anyone crazy enough to
ask for it!

Guy

Before I went completly nuts and put the perimenter ground ring in , I
used clumping
kitty litter, which uses a bentonite and baked/ground clay mixture. I
poured the
kitty litter in to a depth of several inches and added water and
repeated until it was
up to 5 or 6" fro the surface. I also had a capped 1" PVC pipe with
holes drilled
every inch or so that during realy dry summers I would route filtered
grey water from
the washing machine. The ground ring is significantly better as in
lower over all
noise floor, especially for VLF/whistler reception.

The hardest part was convincing the telephone company to use my ground.
They wanted to use a diky 4' ground rod.
Altel oh ya.
Two cans on a string would work as well.

Terry