开云体育

*ERROR......ERROR.......SEE THE RED PARAGRAH*

I didn't proof the write-up as I was becoming fatigued typing. Sorry guys
and gals:


Steve, I completely share our frustration! This is the primary reason I
advise and avoid information by hams and other amateurs in the discipline
presented on YouTuBe. Much of the information presented is just downright
in error. BE CAREFUL!!! In general, the vast majority of the amateur
radio community doing these YouTube presentations truly do not understand
the engineering, technical, and physics of the issues they are attempting
to present. YouTube, in this case, is your enemy. But, you've discovered
that, already!! ???

There are a number of experts within this group who can help you through
your questions. I'll attempt to answer your questions in a rigorous and
true to best engineering practices as I can. Several years ago, I also
posted several procedures for measuring what you are seeking using the
NANOVNA. I'll attach those at the end of this (likely to get far too long)
email.

<<<<<<<<<<<<<<<<<

QUOTE: " some folks how long leads (12-24") being used to connect the DUT
to the nano, other say you need to minimize these lengths (<4"). Still
other says it doesn't matter because when you calibrate the Nano it all
comes out in the wash."

Not everything comes out in the cal. I have a home brew fixture I use for
evaluating ferrites and other lumped components. The component is
captivated between a couple of alligator clips. Those are attached to the
center pins of two BNC chassis mount connectors which are mounted on a
small chunk of solid ground plane on a sheet of FR-4 board. Even with
calibration, much above 150 MHz, that fixture does not function correctly -
too many parasitics the cal. does not account for. This is common.

When addressing connecting lead lengths to/from a DUT (Device Under Test)
first consider the frequency. Within our 2300-Meter band (135 kHz - that's
KILOHertz!) where a full free space wavelength is about 1.4 MILES, lead
length isn't much of a concern. At HF, even at 10-Meters where the full
free space wavelength is about 33-feet at 30 MHz, I'd be cautious of
anything over 6 or so inches. At our L-Band allocation, 1.296 GHz, where a
full free space wavelength is about 9-INCHES, even a 1-inch piece of wire
is very significant.

There is no hard and fast set-in-concrete answer to the lead length issue.
Maybe a twentieth of a free space wavelength long might be used as a
guideline. But there is no hard-and-fast "rule".


QUOTE: "Some instructions show what appears to be a metal plate
"shielding" the nano from the DUT. Or maybe this is just a convenient
mounting plate for frame-mount connectors? I haven't seen the explanation
for why this plate is used, not everyone has one, but the K9YC Choke
Cookbook shows a picture of it and I think k(YC has put more thought into
baluns/ununs than almost anybody so I value that picture -- still don't
know why to do it, but see that he is using it in his measurement jig."

Another caution: Not everything in K9YC's Choke Cookbook is technically
sound. It's a good guide, but understand what he and you are presenting
and constructing. I've locked horns with that publications a few times
right along with a few other technoids on the internet. For an excellent
understanding of baluns and unnnuns, I strongly recommend the subject as
treated at the following URL:

On this site all the information is well presented with absolutely minimal
math, is true to the engineering and physics of the issues, and is, well,
just golden. While it's not a technician-level how-to-build-the-wiget,
it's sound information!

The function of the metal plate is an attempt to isolate the NANOVNA or
measurement device from the DUT. Again, consider free space wavelengths.
In reality, the conducting plate only adds yet another error source to be
accounted for. Also, with the NANOVNA by itself - not connected to
ANYTHING, no USB, no charger cables... - at HF it is a very small portion
of a free space wavelength. The leads to/from the DUT pretty much negate
any possible decoupling the conducting plate might offer.

QUOTE: "Some guidance uses just one Nano port, others use both. Some have
PL-259's on both coax ends (for coax-wrapped baluns) which they plug into
SO-230-SMA adaptors straight into the Nano."

The source port, S11, souces RF energy and is capable of measuring various
REFLECTED parameters to anything connected to it, along. Possible
measurement examples are SWR, Return Loss (RL), and complex impedance (R ±
jX, or the Smith Chart).

A 2-Port measurement involves both the source port, S11, AND a RECEIVE
port. Is not doing, the 2-port setup is capable of measuring various
CONDUCTED or THROUGH parameters of a network or device. Possible
measurement examples are filter response, attenuator values, and amplifier
gain.

Each has its own application when it comes to the NANOVNA.

QUOTE: "Others demonstrate measurements with single-conductor wire-wrapped
baluns; still others have double triple, or quad wrapped single conductors
-- which wire ends do you connect to in these cases? All of them, or
should each one individually measure the same?"

As the saying goes, "there are many ways to skin a cat" (please, no offense
to you cat lovers!!). As so with baluns, matching transformers (which are
NOT baluns), unnuns, and the like. Common mode choke or current baluns,
unnuns, linear of toroidal, or wider frequency response, or...... All have
different techniques of winding and choices of circuit equivalent
topologies. Each has its strengths and weaknesses. Doing a serious read
of the DJ0IP reference I gave above will answer many of these questions.

I use toroidal bifilar wound common mode chokes (CMCs) in my antenna feed
system. I have a 450 set of wires fed with parallel conductor transmission
line. In the shack I install the CMC choke between the open wire line and
the input of my home brew single ended (common mode) L-network for matching
what the antenna/transmission line present in the shack to 50 ± j0 ohms. I
use similar chokes wound on both 31 and 43 ferrite material. No single
choke, balun, unnun,...... can properly serve 630 through 6-Meters. Again,
don't be misled by the 4:1 "transformers" indluded in many "antenna
tuners". For one, they don't "tune" the antenna. What's more, they are
only a transformer and NOT a balun and do NOT function well to match either
a higher impedance nor accomplish the transitiion from common mode (coax)
to differential mode (parallel conductor transmission line). There is no
such thing as "one size fits all". K9YC addresses this to a limited
extent. In short, if you go with toroidal cores, 43 material is best at
and above 20-meters. 31 material is best at and below 40-meters.

QUOTe: "Some guides show the use of resistors or capacitors in series or
parallel with the DUT -- are they always needed? What values? Most videos
do not show them being used, but enough do that I wonder if they improve
accuracy. (Kill parasitic capacitance or some such.)"

Two Pointers Here:

1) Resistors are linear and passive devices. They can absorb energy and
transform energy to a different form (current through the resistor into
hear - infrared). They do not change phases within a circuit or
measurement setup. Resistors are ideally not frequency dependent. In the
complex expression for impedance, R ± jX, resistors are the "R" term.

*2)* Capacitors and inductors are reactive. That is to write, they can
and do alter phases within a circuit or measurement setup. They can not
absorb energy or transform energy to a different forms. In the complex
expression for impedance,
R ± jX, reactive components are represented by the " ±jX" term. Capacitive
reactance is designated with the "-" sign and resides in the *LOWER* half
of the Smith Chart. Inductive reactance is designated with the "+" sign
and resides in the *UPPER* half of the Smith Chart.

Reactances can be used for matching sources/loads to each other. You may
see them in some measurement setups for this reason. Loss elements,
resistors, may be introduced to provide attenuation of a signal (maybe from
the outpout of an amplifier) to keep RF levels within proper ranges of the
RECEIVE, S22) port.


QUOTE: "What Nano menu items are selected for measuring the effectiveness
of a balun/unun? Logmag, phase, smith, resistance, reactance, .... The
thing we're actually looking for is Impedance, but the Nano doesn't offer
that directly. What other nano settings are needed? Range offsets, etc??"

1) The SOLE FUNCTION of a balun or unnun is to provide a bilateral
transition between common mode (CM) and differential mode (DM). Coaxial
cable functions as a CM transmission line. Parallel conductor cable
functions as a DM transmission line. A balun is NOT a transformer or
matching device which the suppliers of "antenna tuners" have you believe.

CM energy on the outside surface of a coaxial cable is, as stated, common
mode. Therefore, a proper balun or common mode choke (CMC) of unnun can
and does function to discourage CM currents from flowing on the coax outer
braid. In so doing it 1) keeps the coaxial feedline from becoming a
portion of the radiating structure and, 2) discourages CM energy from
degrading the received noise floor due to close-by RFI sources.

As such an important parameter to measure for baluns, unnuns, and CMCs is
the CMRR or Common Mode Rejection Ration. This can be measured with the
NANOVNA by measuring the total series inductance presented by the CMC,
balun, or unun. This can be accomplished either as a single (reflection)
or dual (transmission) port measurement. Most baluns, CMCs, and unnuns
form a reflective and absorptive "filter" for CM energy. Therefore, the
series inductance is important. And,....remember, that reflective property
is frequency dependent!

Loss through the CMC, balun, or unnun is also a major consideration.
Therefore, the transmission loss through the DUT should be made. This, as
well, is easily acomplished with the NANOVNAs configured in either the
single port (reflection) or dual port (transmission) port.

This has become WAY TOO LONG, But if you read it as well as the DJ0IP
reference, you will be well on your way. And don't forget my write-ups of
a couple of years ago on using the NANOVNA to make these measurements.

Oh, Yes, another excellent reference is *Reflections II Transmission Lines
and Antennas* by Maxwell, published by WorldRadio Books in paperback hard
print or online. I recently bought my copy for $20 on Amazon. It, as well
as the DJ0IP reference will explain many things all about RF and dispell a
plethora of half-truths and snake oil so prevalent in amateur circles.

Good luck!!!

I'm getting fatigued at typing.......???

Dave - W?LEV

On Thu, Mar 9, 2023 at 10:17?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:

Steve, I completely share our frustration! This is the primary reason I
advise and avoid information by hams and other amateurs in the discipline
presented on YouTuBe. Much of the information presented is just downright
in error. BE CAREFUL!!! In general, the vast majority of the amateur
radio community doing these YouTube presentations truly do not understand
the engineering, technical, and physics of the issues they are attempting
to present. YouTube, in this case, is your enemy. But, you've discovered
that, already!! ???

There are a number of experts within this group who can help you through
your questions. I'll attempt to answer your questions in a rigoruous and
true to best engineering practices as I can. Several years ago, I also
posted several procedures for measuring what you are seeking using the
NANOVNA. I'll attach those at the end of the (likely to get far too long)
email.

<<<<<<<<<<<<<<<<<

QUOTE: " some folks how long leads (12-24") being used to connect the DUT
to the nano, other say you need to minimize these lengths (<4"). Still
other says it doesn't matter because when you calibrate the Nano it all
comes out in the wash."

Not everything comes out in the cal. I have a home brew fixture I use for
evaluating ferrites and other lumped components. The component is
captivated between a couple of alligato clips. Those are attached to the
center pins of two BNC chassis mount connectors which are mounted on a
small chunk of solid ground plane on a sheet of FR-4 board. Even with
calibration, much above 150 MHz, that fixture does not function correctly -
too many parasitics the cal. does not account for. This is common.

When addressing connecting lead lengths to/from a DUT (Device Under Test)
first consider the frequency. Within our 2300-Meter band (135 kHz - that's
KILOHertz!) where a full free space wavelength is about 1.4 MILES, lead
length isn't much of a concern. At HF, even at 10-Meters where the full
free space wavelength is about 33-feet at 30 MHz, I'd be cautious with
anything over 6 or so inches. At our L-Band allocation, 1.296 GHz, where a
full free space wavelength is about 9-INCHES, even a 1-inch piece of wire
is very significant.

There is no hard and fast set-in-concrete answer to the lead length issue.
Maybe a twentieth of a free space wavelength long might be used as a
guideline. But there is no hard-and-fast "rule".


QUOTE: "Some instructions show what appears to be a metal plate
"shielding" the nano from the DUT. Or maybe this is just a convenient
mounting plate for frame-mount connectors? I haven't seen the explanation
for why this plate is used, not everyone has one, but the K9YC Choke
Cookbook shows a picture of it and I think k(YC has put more thought into
baluns/ununs than almost anybody so I value that picture -- still don't
know why to do it, but see that he is using it in his measurement jig."

Another caution: Not everything in K9YC's Choke Cookbook is technically
sound. It's a good guide, but understand what he and you are presenting
and constructing. I've locked horns with that publications a few times
right along with a few other technoids on the internet. For an excellent
understanding of baluns and unnnuns, I strongly recommend the subject as
treated at the following URL:

On this site all the information is well presented with absolutely minimal
math, is true to the engineering and physics of the issues, and is, well,
just golden. While it's not a technician-level how-to-build-the-wiget,
it's sound information!

The function of the metal plate is an attempt to isolate the NANOVNA or
measurement device from the DUT. Again, consider free space wavelengths.
In reality, the conducting plate only adds yet another error source to be
accounted for. Also, with the NANOVNA by itself - not connected to
ANYTHING, no USB, no charger cables... - at HF it is a very small portion
of a free space wavelength. The leads to/from the DUT pretty much negate
any possible decoupling the conducting plate might offer.

QUOTE: "Some guidance uses just one Nano port, others use both. Some have
PL-259's on both coax ends (for coax-wrapped baluns) which they plug into
SO-230-SMA adaptors straight into the Nano."

The source port, S11, souces RF energy and is capable of measuring various
REFLECTED parameters to anything connected to it, along. Possible
measurement examples are SWR, Return Loss (RL), and complex impedance (R ±
jX, or the Smith Chart).

A 2-Port measurement involves both the source port, S11, AND a RECEIVE
port. Is not doing, the 2-port setup is capable of measuring various
CONDUCTED or THROUGH parameters of a network or device. Possible
measurement examples are filter response, attenuator values, and amplifier
gain.

Each has its own application when it comes to the NANOVNA.

QUOTE: "Others demonstrate measurements with single-conductor wire-wrapped
baluns; still others have double triple, or quad wrapped single conductors
-- which wire ends do you connect to in these cases? All of them, or
should each one individually measure the same?"

As the saying goes, "there are many ways to skin a cat" (please, no offense
to you cat lovers!!). As so with baluns, matching transformers (which are
NOT baluns), unnuns, and the like. Common mode choke or current baluns,
unnuns, linear of toroidal, or wider frequency response, or...... All have
different techniques of winding and choices of circuit equivalent
topologies. Each has its strengths and weaknesses. Doing a serious read
of the DJ0IP reference I gave above will answer many of these questions.

I use toroidal bifilar wound common mode chokes (CMCs) in my antenna feed
system. I have a 450 set of wires fed with parallel conductor transmission
line. In the shack I install the CMC choke between the open wire line and
the input of my home brew single ended (common mode) L-network for matching
what the antenna/transmission line present in the shack to 50 ± j0 ohms. I
use similar chokes wound on both 31 and 43 ferrite material. No single
choke, balun, unnun,...... can properly serve 630 through 6-Meters. Again,
don't be misled by the 4:1 "transformers" indluded in many "antenna
tuners". For one, they don't "tune" the antenna. What's more, they are
only a transformer and NOT a balun and do NOT function well to match either
a higher impedance nor accomplish the transitiion from common mode (coax)
to differential mode (parallel conductor transmission line). There is no
such thing as "one size fits all". K9YC addresses this to a limited
extent. In short, if you go with toroidal cores, 43 material is best at
and above 20-meters. 31 material is best at and below 40-meters.

QUOTe: "Some guides show the use of resistors or capacitors in series or
parallel with the DUT -- are they always needed? What values? Most videos
do not show them being used, but enough do that I wonder if they improve
accuracy. (Kill parasitic capacitance or some such.)"

Two Pointers Here:

1) Resistors are linear and passive devices. They can absorb energy and
transform energy to a different form (current through the resistor into
hear - infrared). They do not change phases within a circuit or
measurement setup. Resistors are ideally not frequency dependent. In the
complex expression for impedance, R ± jX, resistors are the "R" term.

2) Capacitors and inductors are reactive. That is to write, they can and
do alter phases within a circuit or measurement setup. They can not absorb
energy or transform energy to a different forms. In the complex expression
for impedance,
R ± jX, reactive components are represented by the " ±jX" term. Capacitive
reactance is designated with the "-" sign and resides in the upper half of
the Smith Chart. Inductive reactance is designated with the "+" sign and
resides in the lower half of the Smith Chart.

Reactances can be used for matching sources/loads to each other. You may
see them in some measurement setups for this reason. Loss elements,
resistors, may be introduced to provide attenuation of a signal (maybe from
the outpout of an amplifier) to keep RF levels within proper ranges of the
RECEIVE, S22) port.


QUOTE: "What Nano menu items are selected for measuring the effectiveness
of a balun/unun? Logmag, phase, smith, resistance, reactance, .... The
thing we're actually looking for is Impedance, but the Nano doesn't offer
that directly. What other nano settings are needed? Range offsets, etc??"

1) The SOLE FUNCTION of a balun or unnun is to provide a bilateral
transition between common mode (CM) and differential mode (DM). Coaxial
cable functions as a CM transmission line. Parallel conductor cable
functions as a DM transmission line. A balun is NOT a transformer or
matching device which the suppliers of "antenna tuners" have you believe.

CM energy on the outside surface of a coaxial cable is, as stated, common
mode. Therefore, a proper balun or common mode choke (CMC) of unnun can
and does function to discourage CM currents from flowing on the coax outer
braid. In so doing it 1) keeps the coaxial feedline from becoming a
portion of the radiating structure and, 2) discourages CM energy from
degrading the received noise floor due to close-by RFI sources.

As such an important parameter to measure for baluns, unnuns, and CMCs is
the CMRR or Common Mode Rejection Ration. This can be measured with the
NANOVNA by measuring the total series inductance presented by the CMC,
balun, or unun. This can be accomplished either as a single (reflection)
or dual (transmission) port measurement. Most baluns, CMCs, and unnuns
form a reflective and absorptive "filter" for CM energy. Therefore, the
series inductance is important. And,....remember, that reflective property
is frequency dependent!

Loss through the CMC, balun, or unnun is also a major consideration.
Therefore, the transmission loss through the DUT should be made. This, as
well, is easily acomplished with the NANOVNAs configured in either the
single port (reflection) or dual port (transmission) port.

This has become WAY TOO LONG, But if you read it as well as the DJ0IP
reference, you will be well on your way. And don't forget my write-ups of
a couple of years ago on using the NANOVNA to make these measurements.

Oh, Yes, another excellent reference is *Reflections II Transmission Lines
and Antennas* by Maxwell, published by WorldRadio Books in paperback hard
print or online. I recently bought my copy for $20 on Amazon. It, as well
as the DJ0IP reference will explain many things all about RF and dispell a
plethora of half-truths and snake oil so prevalent in amateur circles.

Good luck!!!

I'm getting fatigued at typing.......???

Dave - W?LEV






On Thu, Mar 9, 2023 at 8:20?PM Steve Johnson <cascadianroot@...>
wrote:

I've been recently trying to piece together all the various conflicting
information on balun and unun measurement with the NanoVNA. The problem

is

not a lack of tutorials, videos, instructions...it is the opposite --

there

are hundreds of such things available. However, they don't agree with

each

other. And, even on this one forum (and other NaoVNA forums), when the
question comes up for a definitive guide, different sets of links are
provided! It appears there ISN'T a definitive guide, rather just a

growing

assortment of good/bad/ugly opinions. So it becomes a problem of "which
advice should I believe?"

To give some examples:

- some folks how long leads (12-24") being used to connect the DUT to the
nano, other say you need to minimize these lengths (<4"). Still other

says

it doesn't matter because when you calibrate the Nano it all comes out in
the wash.
- Some instructions show what appears to be a metal plate "shielding" the
nano from the DUT. Or maybe this is just a convenient mounting plate for
frame-mount connectors? I haven't seen the explanation for why this plate
is used, not everyone has one, but the K9YC Choke Cookbook shows a

picture

of it and I think k(YC has put more thought into baluns/ununs than almost
anybody so I value that picture -- still don't know why to do it, but see
that he is using it in his measurement jig.
- Some guidance uses just one Nano port, others use both. Some have
PL-259's on both coax ends (for coax-wrapped baluns) which they plug into
SO-230-SMA adaptors straight into the Nano.
- Others demonstrate measurements with single-conductor wire-wrapped
baluns; still others have double triple, or quad wrapped single

conductors

-- which wire ends do you connect to in these cases? All of them, or
should each one individually measure the same?
- Some guides show the use of resistors or capacitors in series or
parallel with the DUT -- are they always needed? What values? Most

videos

do not show them being used, but enough do that I wonder if they improve
accuracy. (Kill parasitic capacitance or some such.)
- What Nano menu items are selected for measuring the effectiveness of a
balun/unun? Logmag, phase, smith, resistance, reactance, .... The thing
we're actually looking for is Impedance, but the Nano doesn't offer that
directly. What other nano settings are needed? Range offsets, etc??

So, you see, this is not a simply-answered question. The common
re-occurrence of the question is enough proof of that. And reading

thorough

the boatload of possible linked answers is very time-consuming.

If anyone knows of a guide/video that specifically answers each of the
above questions then please share that one, definitive guide. Is there

any

plan that shows how to build a generic balun/unun/choke test fixture that
can be re-used time after time on an assortment of such devices? And what
sets this recommendation apart from all the others (showing different
things?) Why should I believe the specifically recommended one?

--
*Dave - W?LEV*


--
Dave - W?LEV

--
*Dave - W?LEV*


--
Dave - W?LEV

Dave (W0LEV),

THANK YOU for sharing that! Also, thanks for sharing the attachments!

73, and thanks,
Dave (NK7Z)

ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

Steve, I completely share our frustration! This is the primary reason I
advise and avoid information by hams and other amateurs in the discipline
presented on YouTuBe. Much of the information presented is just downright
in error. BE CAREFUL!!! In general, the vast majority of the amateur
radio community doing these YouTube presentations truly do not understand
the engineering, technical, and physics of the issues they are attempting
to present. YouTube, in this case, is your enemy. But, you've discovered
that, already!! ???

There are a number of experts within this group who can help you through
your questions. I'll attempt to answer your questions in a rigoruous and
true to best engineering practices as I can. Several years ago, I also
posted several procedures for measuring what you are seeking using the
NANOVNA. I'll attach those at the end of the (likely to get far too long)
email.

<<<<<<<<<<<<<<<<<

QUOTE: " some folks how long leads (12-24") being used to connect the DUT
to the nano, other say you need to minimize these lengths (<4"). Still
other says it doesn't matter because when you calibrate the Nano it all
comes out in the wash."

Not everything comes out in the cal. I have a home brew fixture I use for
evaluating ferrites and other lumped components. The component is
captivated between a couple of alligato clips. Those are attached to the
center pins of two BNC chassis mount connectors which are mounted on a
small chunk of solid ground plane on a sheet of FR-4 board. Even with
calibration, much above 150 MHz, that fixture does not function correctly -
too many parasitics the cal. does not account for. This is common.

When addressing connecting lead lengths to/from a DUT (Device Under Test)
first consider the frequency. Within our 2300-Meter band (135 kHz - that's
KILOHertz!) where a full free space wavelength is about 1.4 MILES, lead
length isn't much of a concern. At HF, even at 10-Meters where the full
free space wavelength is about 33-feet at 30 MHz, I'd be cautious with
anything over 6 or so inches. At our L-Band allocation, 1.296 GHz, where a
full free space wavelength is about 9-INCHES, even a 1-inch piece of wire
is very significant.

There is no hard and fast set-in-concrete answer to the lead length issue.
Maybe a twentieth of a free space wavelength long might be used as a
guideline. But there is no hard-and-fast "rule".


QUOTE: "Some instructions show what appears to be a metal plate
"shielding" the nano from the DUT. Or maybe this is just a convenient
mounting plate for frame-mount connectors? I haven't seen the explanation
for why this plate is used, not everyone has one, but the K9YC Choke
Cookbook shows a picture of it and I think k(YC has put more thought into
baluns/ununs than almost anybody so I value that picture -- still don't
know why to do it, but see that he is using it in his measurement jig."

Another caution: Not everything in K9YC's Choke Cookbook is technically
sound. It's a good guide, but understand what he and you are presenting
and constructing. I've locked horns with that publications a few times
right along with a few other technoids on the internet. For an excellent
understanding of baluns and unnnuns, I strongly recommend the subject as
treated at the following URL:

On this site all the information is well presented with absolutely minimal
math, is true to the engineering and physics of the issues, and is, well,
just golden. While it's not a technician-level how-to-build-the-wiget,
it's sound information!

The function of the metal plate is an attempt to isolate the NANOVNA or
measurement device from the DUT. Again, consider free space wavelengths.
In reality, the conducting plate only adds yet another error source to be
accounted for. Also, with the NANOVNA by itself - not connected to
ANYTHING, no USB, no charger cables... - at HF it is a very small portion
of a free space wavelength. The leads to/from the DUT pretty much negate
any possible decoupling the conducting plate might offer.

QUOTE: "Some guidance uses just one Nano port, others use both. Some have
PL-259's on both coax ends (for coax-wrapped baluns) which they plug into
SO-230-SMA adaptors straight into the Nano."

The source port, S11, souces RF energy and is capable of measuring various
REFLECTED parameters to anything connected to it, along. Possible
measurement examples are SWR, Return Loss (RL), and complex impedance (R ±
jX, or the Smith Chart).

A 2-Port measurement involves both the source port, S11, AND a RECEIVE
port. Is not doing, the 2-port setup is capable of measuring various
CONDUCTED or THROUGH parameters of a network or device. Possible
measurement examples are filter response, attenuator values, and amplifier
gain.

Each has its own application when it comes to the NANOVNA.

QUOTE: "Others demonstrate measurements with single-conductor wire-wrapped
baluns; still others have double triple, or quad wrapped single conductors
-- which wire ends do you connect to in these cases? All of them, or
should each one individually measure the same?"

As the saying goes, "there are many ways to skin a cat" (please, no offense
to you cat lovers!!). As so with baluns, matching transformers (which are
NOT baluns), unnuns, and the like. Common mode choke or current baluns,
unnuns, linear of toroidal, or wider frequency response, or...... All have
different techniques of winding and choices of circuit equivalent
topologies. Each has its strengths and weaknesses. Doing a serious read
of the DJ0IP reference I gave above will answer many of these questions.

I use toroidal bifilar wound common mode chokes (CMCs) in my antenna feed
system. I have a 450 set of wires fed with parallel conductor transmission
line. In the shack I install the CMC choke between the open wire line and
the input of my home brew single ended (common mode) L-network for matching
what the antenna/transmission line present in the shack to 50 ± j0 ohms. I
use similar chokes wound on both 31 and 43 ferrite material. No single
choke, balun, unnun,...... can properly serve 630 through 6-Meters. Again,
don't be misled by the 4:1 "transformers" indluded in many "antenna
tuners". For one, they don't "tune" the antenna. What's more, they are
only a transformer and NOT a balun and do NOT function well to match either
a higher impedance nor accomplish the transitiion from common mode (coax)
to differential mode (parallel conductor transmission line). There is no
such thing as "one size fits all". K9YC addresses this to a limited
extent. In short, if you go with toroidal cores, 43 material is best at
and above 20-meters. 31 material is best at and below 40-meters.

QUOTe: "Some guides show the use of resistors or capacitors in series or
parallel with the DUT -- are they always needed? What values? Most videos
do not show them being used, but enough do that I wonder if they improve
accuracy. (Kill parasitic capacitance or some such.)"

Two Pointers Here:

1) Resistors are linear and passive devices. They can absorb energy and
transform energy to a different form (current through the resistor into
hear - infrared). They do not change phases within a circuit or
measurement setup. Resistors are ideally not frequency dependent. In the
complex expression for impedance, R ± jX, resistors are the "R" term.

2) Capacitors and inductors are reactive. That is to write, they can and
do alter phases within a circuit or measurement setup. They can not absorb
energy or transform energy to a different forms. In the complex expression
for impedance,
R ± jX, reactive components are represented by the " ±jX" term. Capacitive
reactance is designated with the "-" sign and resides in the upper half of
the Smith Chart. Inductive reactance is designated with the "+" sign and
resides in the lower half of the Smith Chart.

Reactances can be used for matching sources/loads to each other. You may
see them in some measurement setups for this reason. Loss elements,
resistors, may be introduced to provide attenuation of a signal (maybe from
the outpout of an amplifier) to keep RF levels within proper ranges of the
RECEIVE, S22) port.


QUOTE: "What Nano menu items are selected for measuring the effectiveness
of a balun/unun? Logmag, phase, smith, resistance, reactance, .... The
thing we're actually looking for is Impedance, but the Nano doesn't offer
that directly. What other nano settings are needed? Range offsets, etc??"

1) The SOLE FUNCTION of a balun or unnun is to provide a bilateral
transition between common mode (CM) and differential mode (DM). Coaxial
cable functions as a CM transmission line. Parallel conductor cable
functions as a DM transmission line. A balun is NOT a transformer or
matching device which the suppliers of "antenna tuners" have you believe.

CM energy on the outside surface of a coaxial cable is, as stated, common
mode. Therefore, a proper balun or common mode choke (CMC) of unnun can
and does function to discourage CM currents from flowing on the coax outer
braid. In so doing it 1) keeps the coaxial feedline from becoming a
portion of the radiating structure and, 2) discourages CM energy from
degrading the received noise floor due to close-by RFI sources.

As such an important parameter to measure for baluns, unnuns, and CMCs is
the CMRR or Common Mode Rejection Ration. This can be measured with the
NANOVNA by measuring the total series inductance presented by the CMC,
balun, or unun. This can be accomplished either as a single (reflection)
or dual (transmission) port measurement. Most baluns, CMCs, and unnuns
form a reflective and absorptive "filter" for CM energy. Therefore, the
series inductance is important. And,....remember, that reflective property
is frequency dependent!

Loss through the CMC, balun, or unnun is also a major consideration.
Therefore, the transmission loss through the DUT should be made. This, as
well, is easily acomplished with the NANOVNAs configured in either the
single port (reflection) or dual port (transmission) port.

This has become WAY TOO LONG, But if you read it as well as the DJ0IP
reference, you will be well on your way. And don't forget my write-ups of
a couple of years ago on using the NANOVNA to make these measurements.

Oh, Yes, another excellent reference is *Reflections II Transmission Lines
and Antennas* by Maxwell, published by WorldRadio Books in paperback hard
print or online. I recently bought my copy for $20 on Amazon. It, as well
as the DJ0IP reference will explain many things all about RF and dispell a
plethora of half-truths and snake oil so prevalent in amateur circles.

Good luck!!!

I'm getting fatigued at typing.......???

Dave - W?LEV






On Thu, Mar 9, 2023 at 8:20?PM Steve Johnson <cascadianroot@...>
wrote:

I've been recently trying to piece together all the various conflicting
information on balun and unun measurement with the NanoVNA. The problem is
not a lack of tutorials, videos, instructions...it is the opposite -- there
are hundreds of such things available. However, they don't agree with each
other. And, even on this one forum (and other NaoVNA forums), when the
question comes up for a definitive guide, different sets of links are
provided! It appears there ISN'T a definitive guide, rather just a growing
assortment of good/bad/ugly opinions. So it becomes a problem of "which
advice should I believe?"

To give some examples:

- some folks how long leads (12-24") being used to connect the DUT to the
nano, other say you need to minimize these lengths (<4"). Still other says
it doesn't matter because when you calibrate the Nano it all comes out in
the wash.
- Some instructions show what appears to be a metal plate "shielding" the
nano from the DUT. Or maybe this is just a convenient mounting plate for
frame-mount connectors? I haven't seen the explanation for why this plate
is used, not everyone has one, but the K9YC Choke Cookbook shows a picture
of it and I think k(YC has put more thought into baluns/ununs than almost
anybody so I value that picture -- still don't know why to do it, but see
that he is using it in his measurement jig.
- Some guidance uses just one Nano port, others use both. Some have
PL-259's on both coax ends (for coax-wrapped baluns) which they plug into
SO-230-SMA adaptors straight into the Nano.
- Others demonstrate measurements with single-conductor wire-wrapped
baluns; still others have double triple, or quad wrapped single conductors
-- which wire ends do you connect to in these cases? All of them, or
should each one individually measure the same?
- Some guides show the use of resistors or capacitors in series or
parallel with the DUT -- are they always needed? What values? Most videos
do not show them being used, but enough do that I wonder if they improve
accuracy. (Kill parasitic capacitance or some such.)
- What Nano menu items are selected for measuring the effectiveness of a
balun/unun? Logmag, phase, smith, resistance, reactance, .... The thing
we're actually looking for is Impedance, but the Nano doesn't offer that
directly. What other nano settings are needed? Range offsets, etc??

So, you see, this is not a simply-answered question. The common
re-occurrence of the question is enough proof of that. And reading thorough
the boatload of possible linked answers is very time-consuming.

If anyone knows of a guide/video that specifically answers each of the
above questions then please share that one, definitive guide. Is there any
plan that shows how to build a generic balun/unun/choke test fixture that
can be re-used time after time on an assortment of such devices? And what
sets this recommendation apart from all the others (showing different
things?) Why should I believe the specifically recommended one?

--
*Dave - W?LEV*


--
Dave - W?LEV

While it is true, no calibration is required to see the resonate points of the plate choke. You will see in the log magnitude sweep the “dips” at particular frequencies. However, you have no notion, are those parallel or anti resonate points or series. It is the series ones that are potentially problematic, particularly if they are in band! If you cal just as a one port, for S11 and use the polar chart, then the series and parallel points will be obvious and accurate. The vna has a distinctive advantage over the GDO, in that both the series and parallel points stand out in the polar sweep. When using the GDO, you would short across the RFC terminals to look for the series resonate dip. Not needed with the vna. I just ran an old National R-175 plate choke. As originally released this choke had a nasty fire hazard issue when operated near the 15 meter band. Sure enough, placed on the vna, that series point is clearly visible. It is accompanied by another point but fortunate, not in any ham band. If you want to see nice pretty circle resonance loops, use a lot of points. The 101 points is sort of a sloppy looking circle.

73' Alan

Actually looking for resonances on a plate choke doesn't even "require"
calibration. Since you're only looking for the frequencies of resonances,
no cal. is required. Treat it like you would a grid dip oscillator
(GDO). Attach a coil roughly of the same diameter of the choke. Only two
or three turns of maybe AWG #18 or #16 enameled wire. Attach the coil
across the source port (S11) - one end of the coil to the center pin of the
source port and the other pin to the backshell of the source port
connector. Set up your start/stop frequencies appropriately accounting
for the maximum number of points so you don't miss resonances. Then hold
the coil close and along the same long axis as the choke - loose coupling.
Display return loss (RL) on the NANOVNA. For each resonance frequency on
the choke, the RL will exhibit a dip, much like the old GDO.

The (mostly) unloaded Q will be the 3 dB bandwidth of the RL dip divided by
the frequency at maximum dip in the RT. frequency.

You need to attach a short and large gauge wire directly across the choke
before making measurements.

If you've ever used a GDO in the past, the approach is identical.

Dave - W?LEV

--
Dave - W?LEV

I looked at W8JI's page on plate chokes..... and trying to figure out how he does the test cables and general setup for testing plate chokes...esp to arrive at RP values across 160-10m..and also Q,
I'm experimenting with a bunch of hb plate chokes, and some are loaded types.
My NanoVNA just arrived late last night.... and I went through the toutorial on the files page of this group..and see that this latest version I just got has a ton of new features not on the tutorial.

It's a steep learning curve.

Any tips would be greatly appreciated. I see that I'm gonna need more cables to make this work. Ok, with cable exrensions added, say SMA to uhf female / BNC..... how do u do the open /short / 50 ohm calibration ? Can i just open / short / add 50 ohms to the cable extension ? Chokes will be stood vertical, so a sidewall would have to be used as the grnd return ?

Jim VE7RF

What he said!
Please.
Regards,
Kirk, NT0Z

My book, "Stealth Amateur Radio," is now available from www.stealthamateur.com and on the Amazon Kindle (soon)

It would be a good practice that if you're using a long cable, the calibration frequency step size should be small enough that you don't get a phase wrap between steps. It's like FFT based TDR.

That is, if |(length/lambda1 - length/lambda2)| > 1 you've got a problem.

or (l*f1/300 - l*f2/300) >1, or l * |f1-f2|/300 > 1.

for a 10 meter cable, this is a delta F of 30 MHz -> 10/300*(30) = 1

(you can also think of it this way, if the cable is longer than the wavelength of the step size, you've got a problem)

(Don't forget to add the velocity factor in.. Length, above, is free space)



This is a potential problem if you're using just the NanoVNA with 101 points over a wide range, for instance.

With NanoVNA-Saver (and maybe NanoVNA-App, I don't use it) you can have a lot more points. And conceivably one could modify those apps to have uneven spacing (i.e. closer together at higher frequencies, where the phase changes more quickly)

I've been recently trying to piece together all the various conflicting information on balun and unun measurement with the NanoVNA. The problem is not a lack of tutorials, videos, instructions...it is the opposite -- there are hundreds of such things available. However, they don't agree with each other. And, even on this one forum (and other NaoVNA forums), when the question comes up for a definitive guide, different sets of links are provided! It appears there ISN'T a definitive guide, rather just a growing assortment of good/bad/ugly opinions. So it becomes a problem of "which advice should I believe?"

To give some examples:

- some folks how long leads (12-24") being used to connect the DUT to the nano, other say you need to minimize these lengths (<4"). Still other says it doesn't matter because when you calibrate the Nano it all comes out in the wash.
- Some instructions show what appears to be a metal plate "shielding" the nano from the DUT. Or maybe this is just a convenient mounting plate for frame-mount connectors? I haven't seen the explanation for why this plate is used, not everyone has one, but the K9YC Choke Cookbook shows a picture of it and I think k(YC has put more thought into baluns/ununs than almost anybody so I value that picture -- still don't know why to do it, but see that he is using it in his measurement jig.
- Some guidance uses just one Nano port, others use both. Some have PL-259's on both coax ends (for coax-wrapped baluns) which they plug into SO-230-SMA adaptors straight into the Nano.
- Others demonstrate measurements with single-conductor wire-wrapped baluns; still others have double triple, or quad wrapped single conductors -- which wire ends do you connect to in these cases? All of them, or should each one individually measure the same?
- Some guides show the use of resistors or capacitors in series or parallel with the DUT -- are they always needed? What values? Most videos do not show them being used, but enough do that I wonder if they improve accuracy. (Kill parasitic capacitance or some such.)
- What Nano menu items are selected for measuring the effectiveness of a balun/unun? Logmag, phase, smith, resistance, reactance, .... The thing we're actually looking for is Impedance, but the Nano doesn't offer that directly. What other nano settings are needed? Range offsets, etc??

So, you see, this is not a simply-answered question. The common re-occurrence of the question is enough proof of that. And reading thorough the boatload of possible linked answers is very time-consuming.

If anyone knows of a guide/video that specifically answers each of the above questions then please share that one, definitive guide. Is there any plan that shows how to build a generic balun/unun/choke test fixture that can be re-used time after time on an assortment of such devices? And what sets this recommendation apart from all the others (showing different things?) Why should I believe the specifically recommended one?

Why do you think that your new NanoVNA needs a firmware upgrade? If you purchase a known version, there should be no reason that a new device should immediately need a firmware upgrade.

After you have used the device for some time and have determined that there is a defect or a documented feature that is not working properly, then you can look for an upgrade.

In summary, in response to your questions...
1. "Best" firmware version should have already been installed unless you purchased a knockoff device.
2.? Check the reviews for the product you purchased (this should have been done before your order was placed).
3.? You did not buy your NanoVNA with a case??? Most NanoVNA devices can be purchased with a suitable case.

On Thursday 09 March 2023 10:01:07 am Jim Lux wrote:

One thing that's a bit tricky is that with the usual gold plated
connector, you don't know if it's brass or steel under the plating.

Wouldn't a magnet answer that question?


--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On 3/1/23 6:33 AM, Brian Beezley wrote:

On Wed, Mar 1, 2023 at 05:54 AM, <btomek@...> wrote:

I think both separators should be supported when reading the file.

The compiler may not support comma separators. For example, my compiler yields 1 when evaluating this string: 1,234. You can get around this by evaluating the number character by character, which is complicated if you allow scientific notation in all its variations, or you can replace commas with periods. The latter is easy, but it fails when the code processes a CSV file, which some VNAs generate and which most of my programs are designed to handle. It was easy to accommodate commas in the program that checks S-parameter magnitudes since it does not have to deal with CSV files. Incidentally, the updated program is here:

Getting down in the weeds here, but it's not so much the compiler as the parsing library it uses (which might be different at run time and compile time).

You don't have to do it character by character, you can look for either period or comma, split it there, then convert the two pieces separately. You also have to deal with the (optional) E.

But it's a pain, no matter how you do it. On the other hand, you only have to write the generalized routine once.
And for something like Python, I'll bet someone's already written it, but it might take longer to find it than to just write it.

On 3/1/23 5:54 AM, btomek@... wrote:

I changed the code to accommodate your files. One offending point for
OPEN_CHANGED.s1p occurs at 300 MHz. That may provide a clue::

@Brian - My s1p was generated in NanoVNA-App. Whether there is a period or a comma probably depends on operating system's regional settings.
According to wikipedia more countries use a comma instead of a period.
In NanoVNA-App, the lower left corner says what the decimal separator character is. In NanoVNA device, you can choose what the separator should be: Menu/Config/Expert settings/More/Separator
I think both separators should be supported when reading the file.

For SnP (Touchstone, S1P, S2P, etc.) files it's easy, because the values are space delimited.

What's *not* easy is that most of the libraries won't do it for you. You have to parse the data fields, split it at the delimiter, then convert the left and right side and combine them.



When writing, it should be as the standard specifies. If it specifies.

it does not. (If someone wants to get involved in standards making, this would be a nice thing to add. Just define the "decimal separator", either specify one, or say that it's localized and could be either, or whatever. The spec just says "you can use scientific notation".

is a great explanation


is the spec (linked from the Microwave101 site)

Going back to the test, I wanted to check whether the calibration data from the frequency 888750625 is responsible for the measurement result on 888750625 or maybe for something else, such as a bug on a neighboring result. However, it came out that every single calibration point affects 4 results, which was a surprise to me. The value of the result is not important, because the calibration data at the changed points is random, but such that it deviates significantly from what it was. Hence, the result will also be random, and may be > 1.

On 3/1/23 4:18 AM, Brian Beezley wrote:

On Wed, Mar 1, 2023 at 02:25 AM, <btomek@...> wrote:

Full s1p in attachment.

I'm curious why your Touchstone files use commas rather than periods in decimal numbers. The utilities and programs I write used to check for commas and replace them with periods, but to simplify the code I dropped that check after not encountering any files with commas for a long time. None of that software will work with your files. This includes a utility that checks for |Sij| > 1, which is invalid but occurs in several of your files.

Some software is localized, and when you put out a number, by default it uses comma as the "decimal point". In particular the various MS Visual whatevers can do this for dialogs. What's sort of pernicious is that by default, if you bought and installed Windows in the US, it's turned off, so even if you set a different region, it stays "." for decimal point; but if you bought and installed Windows somewhere else, it's turned on, and the decimal separator (and other stuff) is localize to the region setting.

I've also seen this for thousands separator (. in some EU countries, , in US). And, of course for dates (MM-DD-YY vs YY-MM-DD)

it's been a number of years (~5) since I did any significant coding specifically for the Windows platform, so it might be better now, but....

And BTW, packages like QT (on all platforms) have similar issues. They try to make localization easy, but you always wind up with a heterogenous combination.


(I've been caught by this before..)

On 3/1/23 2:25 AM, btomek@... wrote:

Roger, thank you for reproducing the experiment. We have clarity that it is a Bug after all.
I did an experiment in which I change the calibration data for a 4 specific frequencies by editing a copy of the .cal file in Notepad and I compared the s1p results for the correct cal file and the changed one.

Did you change the frequencies in the cal file, or the actual calibration data, keeping the frequencies the same?

There is probably some function that tries to smooth the calibration data, average it or filter it. Perhaps this function is used for interpolation if the calibration frequencies do not match the measurement frequencies.

In general, yes, there's likely some interpolation function.

I would recommend keeping the firmware version that it comes with until you
have used it for awhile and become very familiar with its operation. Newer
versions of firmware have added many useful features, but all versions have
been very solid in basic operation, including your intended use case of
analyzing antenna vswr performance. So there is no real need to upgrade
until you find a feature you want but don't already have.

And no need to worry about chipset performance if the correct firmware is
loaded.

On Thu, Mar 9, 2023, 4:04 AM John Knight via groups.io <john_knight1=
[email protected]> wrote:

Hi,
I am awaiting delivery of my first nanovna H4. It is going to be used to
examine various types of mobile VHF aerial sytems swr performance.
I have never used one and I do NOT know which version or chipset it is
using until it is delivered.

But while I am waiting for it to arrive I would like to try and understand
the following -
1. Which is the "best" stable version of code that I am likely to require.
2. I read there may be "suspect" chipsets, how do I find out if the unit I
purchased is a lemon or not?
3.Is there a professional looking case for the device available anywhere?

Thanks for looking.

Best regards - John

On 2/28/23 5:14 AM, Bob Ecclestone VK2ZRE wrote:

Hi Don,
Wow, what an insight that document is.
The comment on SMA connectors is very telling :
"These connectors do not work well in applications that require repeated connections; they wear out quickly. They work best as one-time only connectors, or in applications that require very few reconnections."

Well, they're typically rated at 500 mate/demate cycles, which is a lot, compared to some of those tiny "snap on" connector which are more like 5-10 cycles.

And that spec is more like a "what it's practical to test to in a reasonable amount of time, so it's in the MIL spec" - They will last a lot longer with moderate care. It's like the VSWR or loss spec - it's what's practical to test to.

The moral: Get yourself a set of SMA M-F Connector Savers.
Also, DO NOT turn the connector, ONLY TURN THE NUT.
The specified torque for brass SMA connectors is 5 in-lb / 56N-cm.

Very much so - Then you can replace your connector saver every once in a while when it gets dirty, or the center socket gets deformed, or the rim of the thread gets dinged.

One thing that's a bit tricky is that with the usual gold plated connector, you don't know if it's brass or steel under the plating.


from the Amphenol data sheet:
Mechanical
Items
Mating Cycles 500 Min
Coupling Mechanism Threaded
Interface Specification MIL-STD-348
Mating Torque (Stainless Steel Plug) 0.8 - 1.1 N-m (7 - 10 in-lbs)
Mating Torque (Brass Plug) 0.3 - 0.6 N-m (3 - 5 in-lbs)



MIL-STD-348 is here


But it's just the dimensions, no torque or performance specs.

Hi,
I am awaiting delivery of my first nanovna H4. It is going to be used to examine various types of mobile VHF aerial sytems swr performance.
I have never used one and I do NOT know which version or chipset it is using until it is delivered.

But while I am waiting for it to arrive I would like to try and understand the following -
1. Which is the "best" stable version of code that I am likely to require.
2. I read there may be "suspect" chipsets, how do I find out if the unit I purchased is a lemon or not?
3.Is there a professional looking case for the device available anywhere?

Thanks for looking.

Best regards - John

On Tue, Mar 7, 2023 at 04:19 PM, Ezequiel Reinaldi wrote:

Is there a way to measure the impedance of a balun (current type, connecting
mesh to mesh), but not as rejection in dB, but directly as impedance values
using the 2 ports?
As a guide, I have seen this website (),
where it exports the sp1 file and lifts it with Excel to convert to impedance,
but when exporting from the nano-vna, the curves are not displayed correctly,
and I cannot find the fault.

Try this link for discussions on this subject...

/g/nanovna-users/topic/97089104?p=Created%2C%2C%2C20%2C1%2C0%2C0

Roger

Terry, yes, this list has lots of traffic.
To Unsubscribe, use the Unsubscribe link at the very bottom of any one of
the emails you get from the group.

There is also a link to Mute a topic, i.e. the thread that email is part of.

Stan