Trying to use log mag and not working now.
I think I overload S21 with more then 10db.
What is the fix anyone now?
I¡¯m hoping some simple right at the port
|
For information only:
Ham-Con this year will be both in-person and online. It is scheduled on Feb, 26th, 2022. Before Feb 20th, entrance is $6, after it is $10. See all the information on
Thanks
Bob, k1bif
|
Re: Proper way to measure cable length
Did anyone read my initial reply to this thread? All this was there, but
not using the TDR.
Dave - W?LEV
toggle quoted message
Show quoted text
On Sat, Feb 12, 2022 at 7:04 PM Timothy Cash <cash.tim@...> wrote: This one is very easy to answer as a cable engineer having used both TDR
and OTDR Test Equipment in the past.
All you do is get an exact known length of cable, attach it to your TDR,
dial in a vp UNTIL you get the exact length on the instrument.
That is the vp by virtue of test and measurement.
OR
Follow this guide:
On Sun, Feb 6, 2022 at 11:33 PM lobos305 via groups.io <lobos305=
[email protected]> wrote:
What velocity factor would you use to measure the physical length of a
cable when you don't know the cable type?
Pat
--
Tim Cash | Senior RF/Optical Systems Engineer
cash.tim@...
--
*Dave - W?LEV*
*Just Let Darwin Work*
|
Re: Proper way to measure cable length
This one is very easy to answer as a cable engineer having used both TDR and OTDR Test Equipment in the past. All you do is get an exact known length of cable, attach it to your TDR, dial in a vp UNTIL you get the exact length on the instrument. That is the vp by virtue of test and measurement. OR Follow this guide: On Sun, Feb 6, 2022 at 11:33 PM lobos305 via groups.io <lobos305= [email protected]> wrote: What velocity factor would you use to measure the physical length of a
cable when you don't know the cable type?
Pat
-- Tim Cash | Senior RF/Optical Systems Engineer cash.tim@...
|
Re: Proper way to measure cable length
Hi Bob,
What I wrote about the 150m is not a calculation of a cable length. I was showing that the electrical length is 200m for a physical length of 150m. :-)
About the quality of the nanoVNA H3.2 that I have: you have to be careful. There's no temperature compensation for example. But on the other hand, I was able to measure resistance <0.5 ohm with good accuracy in the HF range and I also tested the nano on 10kohms. Spot on. But I needed some calculus to get there.
In several articles I have explained how to measure those kind of impedances with the nano. The ways to do that are well known in the professional world, but not to hamradio guys/galls of which I am one ;-)
Arie
Op 12-2-2022 om 01:47 schreef Bob Ecclestone:
toggle quoted message
Show quoted text
For the newbies amongst us, you will find if you MULTIPLY the Electrical Length by the Velocity Factor *(VF) you will get the correct Cable Length.
RF slows down as it travels along a cable compared to its speed in free space, about 300,000,000Kms/sec or 300m per microsecond.
In the example Arie gives, The Cable Length would be 150 * 0.78 = 117m (not ~200m). Hopefully enough
|
Re: Proper way to measure cable length
On Tue, Feb 8, 2022 at 02:16 AM, Arie Kleingeld PA3A wrote:
As an example:
- the measured frequency = 11.7 MHz
- a full wavelength for this frequency = 300 / 11.7 = 25,64m
- a quarter of this is: 25,64 / 4 = 6,41m
So the electrical length of the 5m line = 6,41m and physical length = 5m
Therefore the VF = 5 / 6,41 = 0.78
Now measure the unknown length of transmissionline the same way to find
the frequency where the line is a quarter wavelength long.
Sweep S11 starting at a low frequency for example 500 kHz for a long
transmissionline ** to find the quarterwave frequency. Calculate the
quarter wavelenght in meters; divide it by the VF that you found above
and then you will know the length of the line.
(** A quarter wavelength at 500 kHz is 600m / 4 = 150m and taking into
account the VF, the electrical length will be 150/0,78 = nearly 200m,
should be enough :-)? )
Boy, the guys at CERN should have bought a NanoVNA and used some fancy math instead of building the Large Hadron Collider! That way they could achieve 1.28C for 10's of Euros instead of Billions! (Calculated Cable Length 200 / Electrical length 150 = 1.28) Sorry Arie, easy enough mistake to make. I joined the group a short while ago and am very impressed by the wealth of knowledge and advice out there. So thanks to all contributors. When I saw this post, I was sure someone would reply straight away, but nobody did. I am only doing so to help those who are new to Amateur Radio and/or transmission line theory. The method for determining the Velocity Factor (VF) in the example above is correct. (And very well explained) For the newbies amongst us, you will find if you MULTIPLY the Electrical Length by the Velocity Factor *(VF) you will get the correct Cable Length. RF slows down as it travels along a cable compared to its speed in free space, about 300,000,000Kms/sec or 300m per microsecond. In the example Arie gives, The Cable Length would be 150 * 0.78 = 117m (not ~200m). Hopefully enough :-) Cheers...Bob VK2ZRE
|
Re: Screen reader compatible nanovna software for sight impaired
Hey Daniel:
Yes, there is an accessible piece of software for the NanoVna built by a member of this list Bruce KC1FSZ.
I am also a blind op and now use Bruce's software very effectively with my NanoVNA V4.
You or your friend can get the software here:
It uses a program to allow an interface to HTML and you can use a regular web browser to access the sweep functions for SWR and impedance. Bruce is still developing it to include more of the NanoVNA functions.
I use NVDA and google chrome to access it and everything works very well indeed.
73
Colin VA6BKX
toggle quoted message
Show quoted text
On 2022-02-10 3:35 p.m., Daniel Young wrote: Hello I have a white stick operator friend who has a talking kenwood radio, uk amplifier screen reader compatible linear.
He would like to know if there is any suitable windows software.
I tried NVDA Screen reader he uses and it seems tabbed and reading results in NanoVNA-APP.exe reporting OneOfEleven and not the buttons- which is a shame
Any suggestions gratefully received
|
Screen reader compatible nanovna software for sight impaired
Hello I have a white stick operator friend who has a talking kenwood radio, uk amplifier screen reader compatible linear.
He would like to know if there is any suitable windows software.
I tried NVDA Screen reader he uses and it seems tabbed and reading results in NanoVNA-APP.exe reporting OneOfEleven and not the buttons- which is a shame
Any suggestions gratefully received
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
Great, thanks!
toggle quoted message
Show quoted text
On Feb 10, 2022, at 2:01 PM, Arie Kleingeld PA3A <pa3a@...> wrote:
Hi Andy,
I understand that you are talking about a crystal radio being an LC-circuit, a diode plus capacitor and a headset?
You could measure the imput impedance of that receiver. Thing is that a strong signal of a VNA could drive the diode that it would take current. Then the VNA probably will see another impedance that when the diode was not conducting.
That is what the article was about and why I made that simple attenuators to prevent that. And also wanted to test how well my nanoVNA would cope with that.
Those simple crystal receivers usually are used in MF-range, well I did once in a while. The antenna ( most times a piece of wire) will have a pretty high impedance (resistance and also capacitive reactance) if you measure it. The input impedance of the receiver will be far off 50 ohms so thinking about 50 ohms -matching procedures is not the way to go.
Tapping the antennawire into the coil (directly of via a coupled loop) and tuning the C of the LC circuit is the way I would choose and see what happens. If you hear a lot of bandnoise when you connect the antenna and you can hear the stations you expect, you are on the right path.
That article by the way was one in a series of seven. English versions were all published in the Communicator.
73,
Arie PA3A
Op 10-2-2022 om 15:14 schreef Andrew Kurtz via groups.io:
Hi Arie, read your article with great interest. I understand my nanoVNA, I think, and I understand complex algebra and Z = R + jX. But I get VERY confused by standard radio or ham talk. I made a crystal radio over the past 2 years, and never understood why or how it would be 50 ohms. I always wanted to measure my Z, but I think the main thing the antenna signal is ¡°looking at¡± is my diode, since my tank circuit has near-infinite resistance and thus is almost an open circuit. Are you suggesting I can simply plug my nanoVNA in where my antenna usually goes and get a receiver input impedance? Also, you spent a bunch of time on an attenuator, but later (I think) you concluded you didn¡¯t need it. Why would I want one? Any other suggestions for a naive beginner? I am thinking about matching Z from antenna to receiver, but I can¡¯t measure either, and when I guess at values and then design a little LC circuit to match impedances, I find it will resonate at darn near my target f, sending my desired signal to ground!
Andy
On Feb 10, 2022, at 5:43 AM, Arie Kleingeld PA3A<pa3a@...> wrote:
Coming back on the title, how to measure...
I wrote an article about that a couple of months ago, measuring the input impedance of a Elecraft K3 receiver.
It was published in the SARC Communicator sept- Oct 2021. This is the link:
See page 43
73,
Arie PA3A
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
That was the situation when I tried that concept. Thunderstorms etc. :-)
Arie
Op 10-2-2022 om 21:32 schreef W0LEV:
toggle quoted message
Show quoted text
Unless you live in an extremely RFI prone and RFI polluted area, you won't
hear "antenna noise" on a crystal set.
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
Unless you live in an extremely RFI prone and RFI polluted area, you won't
hear "antenna noise" on a crystal set.
Further, the crystal set runs on voltage so the high-Z antenna is quite
appropriate, but not for the 50-ohm system of the NANOs.
The one I finally built a decade or so ago for fun, used taps on the
primary coil of the LC tuned network for the detector. That enables
adjustment of the trade-off between recovered audio and selectivity (tuned
Q). I coupled the antenna to the main coil of the LC network through a
much smaller (inductance) coil to allow best selectivity of the main
inductor. Here in N. Colorado in the evening when the D-Layer dissolves,
I've detected as many and separated up to 23 stations using a 480-foot long
doublet. That's in the presence of our nemesis blowtorch at 760 kHz out of
Boulder which at times measures as much as -30 dBm into 50-ohms (spectrum
analuzer).
To better understand resonance, I believe everyone starting in ham radio
should build his/her own crystal radio. It's an excellent
teaching/learning tool!
Dave - W?LEV
toggle quoted message
Show quoted text
On Thu, Feb 10, 2022 at 7:01 PM Arie Kleingeld PA3A <pa3a@...> wrote: Hi Andy,
I understand that you are talking about a crystal radio being an
LC-circuit, a diode plus capacitor and a headset?
You could measure the imput impedance of that receiver. Thing is that a
strong signal of a VNA could drive the diode that it would take current.
Then the VNA probably will see another impedance that when the diode was
not conducting.
That is what the article was about and why I made that simple
attenuators to prevent that. And also wanted to test how well my
nanoVNA would cope with that.
Those simple crystal receivers usually are used in MF-range, well I did
once in a while. The antenna ( most times a piece of wire) will have a
pretty high impedance (resistance and also capacitive reactance) if you
measure it. The input impedance of the receiver will be far off 50 ohms
so thinking about 50 ohms -matching procedures is not the way to go.
Tapping the antennawire into the coil (directly of via a coupled loop)
and tuning the C of the LC circuit is the way I would choose and see
what happens. If you hear a lot of bandnoise when you connect the
antenna and you can hear the stations you expect, you are on the right
path.
That article by the way was one in a series of seven. English versions
were all published in the Communicator.
73,
Arie PA3A
Op 10-2-2022 om 15:14 schreef Andrew Kurtz via groups.io:
Hi Arie, read your article with great interest. I understand my nanoVNA, I think, and I understand complex algebra and Z = R + jX. But I
get VERY confused by standard radio or ham talk. I made a crystal radio
over the past 2 years, and never understood why or how it would be 50
ohms. I always wanted to measure my Z, but I think the main thing the
antenna signal is ¡°looking at¡± is my diode, since my tank circuit has
near-infinite resistance and thus is almost an open circuit. Are you
suggesting I can simply plug my nanoVNA in where my antenna usually goes
and get a receiver input impedance? Also, you spent a bunch of time on an
attenuator, but later (I think) you concluded you didn¡¯t need it. Why would
I want one? Any other suggestions for a naive beginner? I am thinking
about matching Z from antenna to receiver, but I can¡¯t measure either, and
when I guess at values and then design a little LC circuit to match
impedances, I find it will resonate at darn near my target f, sending my
desired signal to ground!
Andy
On Feb 10, 2022, at 5:43 AM, Arie Kleingeld PA3A<pa3a@...>
wrote:
Coming back on the title, how to measure...
I wrote an article about that a couple of months ago, measuring the
input impedance of a Elecraft K3 receiver.
It was published in the SARC Communicator sept- Oct 2021. This is the
link:
See page 43
73,
Arie PA3A
--
*Dave - W?LEV*
*Just Let Darwin Work*
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
Hi Andy,
I understand that you are talking about a crystal radio being an LC-circuit, a diode plus capacitor and a headset?
You could measure the imput impedance of that receiver. Thing is that a strong signal of a VNA could drive the diode that it would take current. Then the VNA probably will see another impedance that when the diode was not conducting.
That is what the article was about and why I made that simple attenuators to prevent that. And also wanted to test how well? my nanoVNA would cope with that.
Those simple crystal receivers usually are used in MF-range, well I did once in a while. The antenna ( most times a piece of wire) will have a pretty high impedance (resistance and also capacitive reactance) if you measure it. The input impedance of the receiver will be far off 50 ohms so thinking about 50 ohms -matching procedures is not the way to go.
Tapping the antennawire into the coil (directly of via a coupled loop) and tuning the C of the LC circuit is the way I would choose and see what happens. If you hear a lot of bandnoise when you connect the antenna and you can hear the stations you expect, you are on the right path.
That article by the way was one in a series of seven. English versions were all published in the Communicator.
73,
Arie PA3A
Op 10-2-2022 om 15:14 schreef Andrew Kurtz via groups.io:
toggle quoted message
Show quoted text
Hi Arie, read your article with great interest. I understand my nanoVNA, I think, and I understand complex algebra and Z = R + jX. But I get VERY confused by standard radio or ham talk. I made a crystal radio over the past 2 years, and never understood why or how it would be 50 ohms. I always wanted to measure my Z, but I think the main thing the antenna signal is ¡°looking at¡± is my diode, since my tank circuit has near-infinite resistance and thus is almost an open circuit. Are you suggesting I can simply plug my nanoVNA in where my antenna usually goes and get a receiver input impedance? Also, you spent a bunch of time on an attenuator, but later (I think) you concluded you didn¡¯t need it. Why would I want one? Any other suggestions for a naive beginner? I am thinking about matching Z from antenna to receiver, but I can¡¯t measure either, and when I guess at values and then design a little LC circuit to match impedances, I find it will resonate at darn near my target f, sending my desired signal to ground!
Andy
On Feb 10, 2022, at 5:43 AM, Arie Kleingeld PA3A<pa3a@...> wrote:
Coming back on the title, how to measure...
I wrote an article about that a couple of months ago, measuring the input impedance of a Elecraft K3 receiver.
It was published in the SARC Communicator sept- Oct 2021. This is the link:
See page 43
73,
Arie PA3A
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
Hi Dave
And that port is designed to look at a 50 Ohm load, not look like a 50 Ohm load!
Sweeping the front end of most radios just gives you an idea of their preseclection.? ? ?Kent WA5VJB
toggle quoted message
Show quoted text
On Thursday, February 10, 2022, 10:51:56 AM CST, W0LEV <davearea51a@...> wrote: They don't try.? It's that simple.? I've measured only one "vintage" radio of some 30 that put S-9 close to -73 dBm.? That was the Swan 100MX.? Of course, the rest of the S-Meter response is wonkered as is the Kenwood TS-2000. The ability to indicate proper S-Units vs. input power has been around since cell phones.? There is an 80 dB dynamic range requirement to properly measure the received strength for cell phones to properly operate.? It's the RSS output from the "IF" chip, or equivalent.? This could have easily been incorporated into our radios long....long ago, but they didn't. Today, with the SDR receivers, it's a no-brainer and they are pretty accurate (at least for my Icom 7300, 7610, Airspys, and RSP). Dave - W?LEV On Thu, Feb 10, 2022 at 2:06 AM Max via groups.io <kg4pid= [email protected]> wrote: ? I believe it. My very old (now) Icom 2100 single band VHF radio is even
worse. I've seen the meter go from S1 to S9 with only a 6 to 7 db increase
in power from the other end! Just asking, is it really that hard to measure
signal strength with even the least bit of accuracy in a radio? Or it they
just didn't try?
Max KG4PID
? On Wednesday, February 9, 2022, 07:36:03 PM CST, W0LEV <
davearea51a@...> wrote:
? Input regarding Kenwood S-Meters.? I have and have rigorously measured the
S-Meter input power vs. S-meter indication.? It's off the wall for that
radio, if there were a wall!!? At some points below S-9, as little as 1 dBm
difference produces an additional S-Unit increase/decrease.? S-9 is no
where near -73 dBm.? However, above S-9, it's not bad for every 10 dB
increase in input power.? If it's not a modern SDR, the S-Meter doesn't
mean squat - even the Collins S-Line!!!!!!
With S-9 at -73 dBm, that would be +34 dBuV in a non-reactive 50-ohm
system.? 20 over S-9 would be 40 dB (voltage) over that or +74 dBuV.? To be
rigorous, the given value of 100 eBuV is incorrect to be rigorous.? What's
more, what does Kenwood mean by "dBuVEMF"???? What the dickens does the
added "EMF" refer to????
Dave - W?LEV
On Wed, Feb 9, 2022 at 5:25 AM VK2CZ DAVID <16240244c1@...> wrote:
During Kenwood transceiver bench alignments, they specify 100dBuVEMF as
the S9+20 outer marker.? This equates to -1dBm.? As an anecdote, during a
contest with multi-transmitters, we saw around 3Volts of RF at one receiver
(tuned to a different band of course), and it survived quite happily. Best
I can make out, the NanoVNA only outputs like -10dBm.. ??
--
*Dave - W?LEV*
*Just Let Darwin Work*
-- *Dave - W?LEV* *Just Let Darwin Work*
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
They don't try. It's that simple. I've measured only one "vintage" radio of some 30 that put S-9 close to -73 dBm. That was the Swan 100MX. Of course, the rest of the S-Meter response is wonkered as is the Kenwood TS-2000. The ability to indicate proper S-Units vs. input power has been around since cell phones. There is an 80 dB dynamic range requirement to properly measure the received strength for cell phones to properly operate. It's the RSS output from the "IF" chip, or equivalent. This could have easily been incorporated into our radios long....long ago, but they didn't. Today, with the SDR receivers, it's a no-brainer and they are pretty accurate (at least for my Icom 7300, 7610, Airspys, and RSP). Dave - W?LEV On Thu, Feb 10, 2022 at 2:06 AM Max via groups.io <kg4pid= [email protected]> wrote: I believe it. My very old (now) Icom 2100 single band VHF radio is even
worse. I've seen the meter go from S1 to S9 with only a 6 to 7 db increase
in power from the other end! Just asking, is it really that hard to measure
signal strength with even the least bit of accuracy in a radio? Or it they
just didn't try?
Max KG4PID
On Wednesday, February 9, 2022, 07:36:03 PM CST, W0LEV <
davearea51a@...> wrote:
Input regarding Kenwood S-Meters. I have and have rigorously measured the
S-Meter input power vs. S-meter indication. It's off the wall for that
radio, if there were a wall!! At some points below S-9, as little as 1 dBm
difference produces an additional S-Unit increase/decrease. S-9 is no
where near -73 dBm. However, above S-9, it's not bad for every 10 dB
increase in input power. If it's not a modern SDR, the S-Meter doesn't
mean squat - even the Collins S-Line!!!!!!
With S-9 at -73 dBm, that would be +34 dBuV in a non-reactive 50-ohm
system. 20 over S-9 would be 40 dB (voltage) over that or +74 dBuV. To be
rigorous, the given value of 100 eBuV is incorrect to be rigorous. What's
more, what does Kenwood mean by "dBuVEMF"??? What the dickens does the
added "EMF" refer to????
Dave - W?LEV
On Wed, Feb 9, 2022 at 5:25 AM VK2CZ DAVID <16240244c1@...> wrote:
During Kenwood transceiver bench alignments, they specify 100dBuVEMF as
the S9+20 outer marker. This equates to -1dBm. As an anecdote, during a
contest with multi-transmitters, we saw around 3Volts of RF at one receiver
(tuned to a different band of course), and it survived quite happily. Best
I can make out, the NanoVNA only outputs like -10dBm.. ??
--
*Dave - W?LEV*
*Just Let Darwin Work*
-- *Dave - W?LEV* *Just Let Darwin Work*
|
Thank You
?Larry.
Joe
toggle quoted message
Show quoted text
On 2/10/2022 10:03 AM, Larry Rothman wrote: Yes
On Thursday, February 10, 2022, 09:59:26 a.m. EST, Joe WB9SBD<nss@...> wrote:
Simple question
OK NanoVNA-H4 Unit is off and is charging via the USB cable.
Red light is flashing I assume meand charging
when it is steady and not flashing does that mean it is fully charged?
Joe
|
Yes
toggle quoted message
Show quoted text
On Thursday, February 10, 2022, 09:59:26 a.m. EST, Joe WB9SBD <nss@...> wrote:
Simple question
OK NanoVNA-H4 Unit is off and is charging via the USB cable.
Red light is flashing I assume meand charging
when it is steady and not flashing does that mean it is fully charged?
Joe
|
Simple question
OK NanoVNA-H4 Unit is off and is charging via the USB cable.
Red light is flashing I assume meand charging
when it is steady and not flashing does that mean it is fully charged?
Joe
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
Hi Arie, read your article with great interest. I understand my nanoVNA, I think, and I understand complex algebra and Z = R + jX. But I get VERY confused by standard radio or ham talk. I made a crystal radio over the past 2 years, and never understood why or how it would be 50 ohms. I always wanted to measure my Z, but I think the main thing the antenna signal is ¡°looking at¡± is my diode, since my tank circuit has near-infinite resistance and thus is almost an open circuit. Are you suggesting I can simply plug my nanoVNA in where my antenna usually goes and get a receiver input impedance? Also, you spent a bunch of time on an attenuator, but later (I think) you concluded you didn¡¯t need it. Why would I want one? Any other suggestions for a naive beginner? I am thinking about matching Z from antenna to receiver, but I can¡¯t measure either, and when I guess at values and then design a little LC circuit to match impedances, I find it will resonate at darn near my target f, sending my desired signal to ground!
Andy
toggle quoted message
Show quoted text
On Feb 10, 2022, at 5:43 AM, Arie Kleingeld PA3A <pa3a@...> wrote:
Coming back on the title, how to measure...
I wrote an article about that a couple of months ago, measuring the input impedance of a Elecraft K3 receiver.
It was published in the SARC Communicator sept- Oct 2021. This is the link:
See page 43
73,
Arie PA3A
|
Re: Proper way to measure cable length
Hi dear friends!!!
What kind is your nanovna???
I has purchase few days ago a SAA 2 V2.2 but I cant find this option...
Can You help me please???
Em 07/02/2022 15:39, DiSlord escreveu:
toggle quoted message
Show quoted text
In my firmware exist option
Measure->Cable
User need select correct frequency range (minimum/maximim frequency depend from cable length on smitch chart must rotate by 180 degree)
As can see in this mode Nano measure impedance, length (need set correct velocity factor) and loss (at marker point, use s11 logmag / 2)
|
Re: Using NanoVNA to measure receive antenna port impedance
#measurement
Coming back on the title, how to measure...
I wrote an article about that a couple of months ago, measuring the input impedance of a Elecraft K3 receiver.
It was published in the SARC Communicator sept- Oct 2021. This is the link:
See page 43
73,
Arie PA3A
|
Alan Brown
Arie Kleingeld PA3A
