In the last email on the subject, please forgive me for being a bit cryptic. I'm just so frustrated with what the "memorize and forget" philosophy has gotten us in amateur radio in general. Yes, I know it's become the standard to test well on the standardized tests (public education), but it ain't git'n the job dun. Dave - W?LEV On Sun, Mar 12, 2023 at 7:47?PM W0LEV via groups.io <davearea51a= [email protected]> wrote: Where is the text that went with the attachments?????? Try again:
QUOTE: " But I note that many ¡°internet experts¡± I have read begin their
reports or designs or whatever by stating or thinking they ¡°have ±ð²Ô´Ç³Ü²µ³ó¡± or
¡°²õ³ó´Ç³Ü±ô»å be ±ð²Ô´Ç³Ü²µ³ó¡± common mode impedance without offering a single
measurement, or just thinking the impedance they are worried about is abs
Zcmc, and leave it at that."
Yes, this is due to no real understanding of what they are doing. This is
one major reason I do not recommend consulting amateur YouTube
presentations. As I stated in my original (long....) reply, most of them
truly do not understand what they are attempting to present and many times
are in error.
For one thing, the whole subject of antennas and transmission lines,
including baluns and matching transformers (transformers are NOT baluns) is
one of the most misunderstood and misrepresented aspects in amateur radio
(and a few other online subjects as well). Most of my references (yes,
hard bound thick books on the shelf right in front of me ) are graduate
level texts. These are well above the understanding of likely 97% of the
average amateur in the US. I try my best *not* to present on the
technician level - "this is how you build the widget" mentality. "Don't
worry about how it works. Just take my word, it works.........." This
grates me from the hair on my head to my big left foot toe nail!!! Well,
enough of that rant.......
As far as SWR is concerned, it's important as insurance to keep our output
devices and FETs in our modern amplifiers from reducing themselves back to
their original state: quartz or silicon dioxide. SiO2 is an excellent
insulator and was (and still is) used in frequency control. But it makes a
really bad RF amplifier......!! Have a read of "SWR Meters Make You
Stupid" - attached. I know the author and it's a tongue-in-cheek write-up,
but excellent in content.
Yes, I have measured everything of interest w.r.t. (with respect to) the
CMCs I have built. Those I presently have on the shelf to choose from -
depending on frequency and the complex impedance my feedline/antenna
presents to them in the shack - I have built and measured at least 40
various incantations to come out with 7 on the shelf to choose from at any
given time . Again, there is "no size fits all". I have not to date
presented the results on this forum due to the fact that most amateurs will
not understand the measurements. If they don't understand complex
impedance and use only |Z|, how can they assimilate the measurements?? The
measurements were presented some two years ago on the NANOVNA group
including technician level "how to" make CMRR and through loss measurements
using the NANOVNAs. The procedures should be in the archives of that
group. I'm not going to waist my time explaining something for which the
average amateur has no basis in understanding the rank basics of complex
impedances, the Smith Chart, return loss, and......... Most can't even do
simple algebra (should have been engrained in HS).
As far as the CMRR of the various CMCs, please see the attachment for
measured CMRR values of seven of the chokes as a function of frequency. Of
course, all measurements are made in a rigorous 50-Ohm system. The left
most column is frequency - the amateur bands. The following columns are
the measured CMRRs for the various CMCs in dB as measured on a calibrated
setup using the HP 8753C VNA. The second page presents a key to the seven
chokes which I measured. The fallacy of these measurements is that the
CMRR reflects the choke embedded in a 50-Ohm system. The DM end
(windowline) of the choke is anything but 50-Ohms. Measurements of the
impedance presented by the CMC to the L-network for matching to 50-Ohms is
mostly on the bottom - inductive - side of the smith chart - also included
in the attachments.
I measured the Vp and Z only a few of the CMCs. The Vp's came out around
0.55 and the Zo was between 73 and 103-ohms (if I remember) - calculated
from Zo = ¡Ì[L/C]. I've also included a picture of one of the CMCs. The
loss measurements all came out at or less than 0.6 dB over the seven which
I measured.
I'll also attach a measurement I made documenting the effect of the CMC on
40-meters.
PLEASE: Others read as well. I've continued on the group.io instead of
going private in the hope that others will also learn from reading.
Continuing to learn is the spice of life!!!!
Dave - W?LEV
On Sun, Mar 12, 2023 at 7:42?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:
I hope they (Starlink) doesn't truncate this email, again......
Here it is again.........
QUOTE: " But I note that many ¡°internet experts¡± I have read begin their
reports or designs or whatever by stating or thinking they ¡°have ±ð²Ô´Ç³Ü²µ³ó¡± or
¡°²õ³ó´Ç³Ü±ô»å be ±ð²Ô´Ç³Ü²µ³ó¡± common mode impedance without offering a single
measurement, or just thinking the impedance they are worried about is abs
Zcmc, and leave it at that."
Yes, this is due to no real understanding of what they are doing. This is
one major reason I do not recommend consulting amateur YouTube
presentations. As I stated in my original (long....) reply, most of them
truly do not understand what they are attempting to present and many times
are in error.
For one thing, the whole subject of antennas and transmission lines,
including baluns and matching transformers (transformers are NOT baluns) is
one of the most misunderstood and misrepresented aspects in amateur radio
(and a few other online subjects as well). Most of my references (yes,
hard bound thick books on the shelf right in front of me ) are graduate
level texts. These are well above the understanding of likely 97% of the
average amateur in the US. I try my best *not* to present on the
technician level - "this is how you build the widget" mentality. "Don't
worry about how it works. Just take my word, it works.........." This
grates me from the hair on my head to my big left foot toe nail!!! Well,
enough of that rant.......
As far as SWR is concerned, it's important as insurance to keep our output
devices and FETs in our modern amplifiers from reducing themselves back to
their original state: quartz or silicon dioxide. SiO2 is an excellent
insulator and was (and still is) used in frequency control. But it makes a
really bad RF amplifier......!! Have a read of "SWR Meters Make You
Stupid" - attached. I know the author and it's a tongue-in-cheek write-up,
but excellent in content.
Yes, I have measured everything of interest w.r.t. (with respect to) the
CMCs I have built. Those I presently have on the shelf to choose from -
depending on frequency and the complex impedance my feedline/antenna
presents to them in the shack - I have built and measured at least 40
various incantations to come out with 7 on the shelf to choose from at any
given time . Again, there is "no size fits all". I have not to date
presented the results on this forum due to the fact that most amateurs will
not understand the measurements. If they don't understand complex
impedance and use only |Z|, how can they assimilate the measurements?? The
measurements were presented some two years ago on the NANOVNA group
including technician level "how to" make CMRR and through loss measurements
using the NANOVNAs. The procedures should be in the archives of that
group. I'm not going to waist my time explaining something for which the
average amateur has no basis in understanding the rank basics of complex
impedances, the Smith Chart, return loss, and......... Most can't even do
simple algebra (should have been engrained in HS).
As far as the CMRR of the various CMCs, please see the attachment for
measured CMRR values of seven of the chokes as a function of frequency. Of
course, all measurements are made in a rigorous 50-Ohm system. The left
most column is frequency - the amateur bands. The following columns are
the measured CMRRs for the various CMCs in dB as measured on a calibrated
setup using the HP 8753C VNA. The second page presents a key to the seven
chokes which I measured. The fallacy of these measurements is that the
CMRR reflects the choke embedded in a 50-Ohm system. The DM end
(windowline) of the choke is anything but 50-Ohms. Measurements of the
impedance presented by the CMC to the L-network for matching to 50-Ohms is
mostly on the bottom - inductive - side of the smith chart - also included
in the attachments.
I measured the Vp and Z only a few of the CMCs. The Vp's came out around
0.55 and the Zo was between 73 and 103-ohms (if I remember) - calculated
from Zo = ¡Ì[L/C]. I've also included a picture of one of the CMCs. The
loss measurements all came out at or less than 0.6 dB over the seven which
I measured.
I'll also attach a measurement I made documenting the effect of the CMC on
40-meters.
PLEASE: Others read as well. I've continued on the group.io instead of
going private in the hope that others will also learn from reading.
Continuing to learn is the spice of life!!!!
Dave - W?LEV
On Sun, Mar 12, 2023 at 7:21?PM David Eckhardt <davearea51a@...>
wrote:
Why was my email and the attachments theretoo truncated???????? The whole
email is not present!!!!!!
Dave - W?LEV
On Sun, Mar 12, 2023 at 7:14?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:
QUOTE: " But I note that many ¡°internet experts¡± I have read begin their
reports or designs or whatever by stating or thinking they ¡°have
±ð²Ô´Ç³Ü²µ³ó¡±
or
¡°²õ³ó´Ç³Ü±ô»å be ±ð²Ô´Ç³Ü²µ³ó¡± common mode impedance without offering a single
measurement, or just thinking the impedance they are worried about is
abs
Zcmc, and leave it at that."
Yes, this is due to no real understanding of what they are doing.
This
is
one major reason I do not recommend consulting amateur YouTube
presentations. As I stated in my original (long....) reply, most of
them
truly do not understand what they are attempting to present and many
times
are in error.
For one thing, the whole subject of antennas and transmission lines,
including baluns and matching transformers (transformers are NOT
baluns)
is
one of the most misunderstood and misrepresented aspects in amateur
radio
(and a few other online subjects as well). Most of my references
(yes,
hard bound thick books on the shelf right in front of me ) are
graduate
level texts. These are well above the understanding of likely 97% of
the
average amateur in the US. I try my best *not* to present on the
technician level - "this is how you build the widget" mentality.
"Don't
worry about how it works. Just take my word, it works.........."
This
grates me from the hair on my head to my big left foot toe nail!!!
Well,
enough of that rant.......
As far as SWR is concerned, it's important as insurance to keep our
output
devices and FETs in our modern amplifiers from reducing themselves
back
to
their original state: quartz or silicon dioxide. SiO2 is an
excellent
insulator and was (and still is) used in frequency control. But it
makes
a
really bad RF amplifier......!! Have a read of "SWR Meters Make You
Stupid" - attached. I know the author and it's a tongue-in-cheek
write-up,
but excellent in content.
Yes, I have measured everything of interest w.r.t. (with respect to)
the
CMCs I have built. Those I presently have on the shelf to choose
from -
depending on frequency and the complex impedance my feedline/antenna
presents to them in the shack - I have built and measured at least 40
various incantations to come out with 7 on the shelf to choose from at
any
given time . Again, there is "no size fits all". I have not to date
presented the results on this forum due to the fact that most amateurs
will
not understand the measurements. If they don't understand complex
impedance and use only |Z|, how can they assimilate the measurements??
The
measurements were presented some two years ago on the NANOVNA group
including technician level "how to" make CMRR and through loss
measurements
using the NANOVNAs. The procedures should be in the archives of that
group. I'm not going to waist my time explaining something for which
the
average amateur has no basis in understanding the rank basics of
complex
impedances, the Smith Chart, return loss, and......... Most can't
even
do
simple algebra (should have been engrained in HS).
As far as the CMRR of the various CMCs, please see the attachment for
measured CMRR values of seven of the chokes as a function of
frequency.
Of
course, all measurements are made in a rigorous 50-Ohm system. The
left
most column is frequency - the amateur bands. The following columns
are
the measured CMRRs for the various CMCs in dB as measured on a
calibrated
setup using the HP 8753C VNA. The second page presents a key to the
seven
chokes which I measured. The fallacy of these measurements is that
the
CMRR reflects the choke embedded in a 50-Ohm system. The DM end
(windowline) of the choke is anything but 50-Ohms. Measurements of
the
impedance presented by the CMC to the L-network for matching to
50-Ohms
is
mostly on the bottom - inductive - side of the smith chart - also
included
in the attachments.
I measured the Vp and Z only a few of the CMCs. The Vp's came out
around
0.55 and the Zo was between 73 and 103-ohms (if I remember) -
calculated
from Zo = ¡Ì[L/C]. I've also included a picture of one of the CMCs.
The
loss measurements all came out at or less than 0.6 dB over the seven
which
I measured.
I'll also attach a measurement I made documenting the effect of the
CMC
on
40-meters.
PLEASE: Others read as well. I've continued on the group.io instead
of
going private in the hope that others will also learn from reading.
Continuing to learn is the spice of life!!!!
Dave - W?LEV
On Sun, Mar 12, 2023 at 4:51?PM AG6CX <edwmccann@...> wrote:
Dave -
One last question on your baluns and such
from my inquiry, item 5:
¡°5. Your observed results of Z CMC offered by each CMC choke ? In
form
Z=R
+jX and related Reflection Coefficient Gamma Vector = rho Angle Gamma? Or
»åµþ.¡±
Do you have plots of Z, X and R. Vs frequency of your chokes that
you
might share with us?
I¡¯m interested in how much CMC impedance you think (or know) is
being
introduced by the chokes.
I note that many seminal descriptions of the balun issue begins with
the
colored charts of Steve Hunt, G3TXQ (sk), who opens with a
description
of
the impedance s frequency of various materials.
He concludes with a link describing how he measured, and another to
a
spreadsheet that converts the measurements to Z, R and X.
A pretty complete description.
Some have been unable to recreate the results, and gave offered
their
own
measurements, like Jeff Anderson K6JCA (google and ye shall find),
Jim
Brown K9YC, whose work we have discussed here, and others,
including
Owen
Duffy VK1OD and Tom Rauch W8JI.
But I note that many ¡°internet experts¡± I have read begin their
reports
or designs or whatever by stating or thinking they ¡°have ±ð²Ô´Ç³Ü²µ³ó¡± or ¡°²õ³ó´Ç³Ü±ô»å
be ±ð²Ô´Ç³Ü²µ³ó¡± common mode impedance without offering a single
measurement,
or
just thinking the impedance they are worried about is abs Zcmc, and leave
it at that.
The website of DJ0IP you describe does the same thing. Not a
measurement
beyond SWR. For an estimate of how much impedance? Fall back on
³§³Ù±ð±¹±ð¡¯²õ
coloring book. While it is a collection of interesting bits and
pieces,
the
site is an aggregator of the works of others, but at least offers a
spot
for one-stop shopping. Adherence to the physics and science is not quite as
strict as you maintain.
With regard to figure of merit, there is nothing wrong with looking
hard
at SWR. You will recall an article on searching too hard for the
last
bit
of SWR could be harmful to one¡¯s health! I post an insightful link
to
Owen
Duffy regarding an obsession with chasing phase, but the phase of
what?
Impedance phase or of that presented by reliance on S11 phase, as
the
nifty
RigExpert analyzers present. And as many amateurs seem to confuse.
Again, thanks for your continued contributions to the field!
Looking forward to a description of how much CMC choking you have in
the
baluns installed when you get a minute.
73
Ed McCann
AG6CX
--
*Dave - W?LEV*
--
Dave - W?LEV
--
*Dave - W?LEV*
--
*Dave - W?LEV*
--
Dave - W?LEV
--
*Dave - W?LEV*
--
Dave - W?LEV
-- *Dave - W?LEV* -- Dave - W?LEV
|
