开云体育

On 3/5/23 9:52 AM, N2MS wrote:

I use my NanoVNA from 0.4 to 150 MHz. I wonder of installing a 10uF coupling capacitor with the 1uF would help the low frequency response. Can anyone recommend a SMD part from Mouser or Digikey?
Thanks,
Mike N2MS

On 03/05/2023 8:22 AM Brian Beezley <k6sti@...> wrote:

I've been looking into the S21 and Y21 methods of calculating an unknown impedance connected between the two VNA ports. The port impedances play a role. I used Micro-Cap to model the NanoVNA-H4 rev 4.3 port networks and calculate their input impedance. I used data sheet values for the semiconductor impedances. Port 1 is on the left in the schematic. Blue/red curves are for port 1 and green/brown are for port 2. Even though the AC-coupling filter corners are only a kHz or two, the phase shift they cause extends much higher. I have seen the effect on measurements at a few hundred kHz.

Brian

Wouldn't that come out in the calibration against presumably flat standards?

Here is a 200 uH homemade plate choke. It was fine fro 160 meter - 40 meter where it was parallel resonate.
Higher than that, no way. A significant number of resonate loops. Quite problematic. This was single layer winding with no attempt to break the windings apart and reduce the parasitic C. The view is crop and hope it is clearer.

G'day Jim,

You are quite right of course.
When I wrote the reply to Don I had only just finished reading his referenced Keysight/Agilent/HP document.
I meant to put in a comment that the document was specifically referring to Metrology grade measurements but my head was still spinning from the degree of detail in the document.
It certainly made extremely interesting reading having spent some time in development labs in past lives.

Connector Savers are a real godsend to the fabulous NanoVNAs and TinySAs currently available to us these days. They are the best accessory you can buy for your instruments.
It is interesting also that HP made a range of Connector Savers and Adapters available and characterised the effect they could/would have on measurements.

Cheers...Bob VK2ZRE

I'm getting emails from last week, just showing up today. How odd.


Looking at the headers

I got it at 19:31 (EST) today (= 0031Z, 10 March)

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Got to Earthlink's mta just now (0031Z on 10 March)

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How very odd...
Is this a groups.io weirdness, or an Earthlink weirdness?

Here is a display for S11 from the vna. Sweep is 1 - 30 MHz, 512 points. A simple SOL cal and then a set of clip leads to the choke.
Choke is standing up right on the tube chassis and the rack panel in place. All is good pass 20 meters... Then things get interesting
as you approach 16 MHz and 21 MHz. Be careful there! A simple mod to the R-175 choke spread the top section of windings
out and moved the self capacitance created so that the resonance that exited was well removed from the HF band. On the
vna easy to see. Not so easy using the GDO. Can be done, just takes time and patience!

Please note. At low frequency as expected the shunt measure of the choke starts at the short side of the chart and rotates CW.
Eventually, parallel resonance occurs. Increase frequency some more and there is where the FUN begins.

On Thu, Mar 9, 2023 at 12:26 PM, Jim VE7RF wrote:

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 see W8JI has a link on his site for testing plate chokes, inductors and traps. Down the page he shows the VNA setup and SOL connections.



Roger

On Thu, Mar 9, 2023 at 10:13 AM, Roy J. Tellason, Sr. wrote:

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?

Answer: it depends, but probably not reliably. Some stainless steels are magnetic and some are not; generally for example 300-series stainless steels are non-magnetic while 400-series are. Asking google "What stainless steel are SMA connectors made of" (admittedly this is lazy person's research) returns that they're made of 303, so they would generally be non-magnetic. However, some stainless steels that are non-magnetic can become locally magnetic where they are cold-worked. For example a typical coin cell battery is made from 304 stainless and if you use a small magnet you'll find that the center of it is not attracted to a magnet but the edge of it, where it has been bent around and crimped to form the seal, is attracted to a magnet.
So in summary, I'd expect this to not be a very reliable method on something as small as an SMA connector that is made from a basically non-magnetic base material.

no .... best is maybe in the nanovna bata tes group (displord modds faster as manufacturer can do a blink)

you maybe will get a unit from the stock and so i is more or less sure that fw is old

....

maybe he want to add his own case with a bigger battery, and sma to n or bnc pigtails or adaptors???

case?? in my view should be metal case

dg9bfc sigi

Am 09.03.2023 um 19:17 schrieb David Rounds:

Yea, there is a corrected version. I biffed it on the Smith Chart - BAD
ENGINEER!!!! That's what I get for not proof reading.....

Dave - W?LEV

--
Dave - W?LEV

*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