Re: Back to Back transformer Measurement on SDR-Kits Test board
As a double check I would calibrate at the end of the cable using the supplied S-O-L Then hook up to the SDR board with load and see how it compares to Cal Load. A perfect 50 ohm SM resistor is hard to find.
Very interesting writeup and beyond where I am at the moment. I'm having to learn all over again about how to setup the NanoVNA.
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Sorry, its not the KARN, its the ANNE-50X+. Someone else mentioned another model from Minicircuits. Pick whatever has the best guaranteed performance over the range you want. Ignore the typical performance - that is based on a sample of 1 from Mincircuits, which is a pretty crap way of getting a typical set of data to me, but I was told by a Minicircuits employee that "typical" means one random one taken from the production line. Dr David Kirkby Ph.D C.Eng MIET Email: drkirkby@... Web: Kirkby Microwave Ltd (Tel 01621-680100 / +44 1621-680100) Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT. On Tue, 9 Jun 2020 at 18:23, Dr. David Kirkby < drkirkby@...> wrote: On Tue, 9 Jun 2020 at 18:13, Wes Plouff <ac8jf@...> wrote:
I received my NanoVNA-H4 from AliExpress in just 10 days, and am happy
with my purchase. However, the 50 ohm SMA calibration load goes
intermittently open. The cap rotates even when the load is screwed firmly
to the VNA port connector, so I think the part is defective. The
calibration load from my hugen NanoVNA works properly on the H4.
What are good sources for a replacement part that have good performance
to 1.5 GHz, are reasonably priced, and ship from the USA? Am I stuck buying
an entire calibration kit? Thanks for any advice.
A Minicircuits KARN-50X+ is a pretty decent male load. Mechanically they
are good, and do not rotate as you screw them in. However, unless you
either pay lots of money, or pay someone to measure one for you, there's
never any guarantee of what it will be like. But Minicircuits have a
specification, and 99.999% of their devices meet that specification. You
may find another Minicircuits load with a better guaranteed performance to
a few GHz.
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On Tue, 9 Jun 2020 at 18:13, Wes Plouff <ac8jf@...> wrote: I received my NanoVNA-H4 from AliExpress in just 10 days, and am happy
with my purchase. However, the 50 ohm SMA calibration load goes
intermittently open. The cap rotates even when the load is screwed firmly
to the VNA port connector, so I think the part is defective. The
calibration load from my hugen NanoVNA works properly on the H4.
What are good sources for a replacement part that have good performance to
1.5 GHz, are reasonably priced, and ship from the USA? Am I stuck buying an
entire calibration kit? Thanks for any advice.
A Minicircuits KARN-50X+ is a pretty decent male load. Mechanically they are good, and do not rotate as you screw them in. However, unless you either pay lots of money, or pay someone to measure one for you, there's never any guarantee of what it will be like. But Minicircuits have a specification, and 99.999% of their devices meet that specification. You may find another Minicircuits load with a better guaranteed performance to a few GHz.
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Re: NanoVNA firmvare, compiled by DiSlord #firmware with MiniSD support
#firmware
Thanks DiSlord, I installed miniSD reader and 32.768 kHz xtal on PC 14 and PC15 on my H4 as per your instruction.
The screenshots, s1p and s2p can be saved now on the SD card. I used the NanoVNA H4 v0.93.3 beta_SD Card
LSE_Clock.dfu firmware.
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This model from Mini-Circuits is a good quality unit:
About $7.
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I received my NanoVNA-H4 from AliExpress in just 10 days, and am happy with my purchase. However, the 50 ohm SMA calibration load goes intermittently open. The cap rotates even when the load is screwed firmly to the VNA port connector, so I think the part is defective. The calibration load from my hugen NanoVNA works properly on the H4.
What are good sources for a replacement part that have good performance to 1.5 GHz, are reasonably priced, and ship from the USA? Am I stuck buying an entire calibration kit? Thanks for any advice.
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Re: Back to Back transformer Measurement on SDR-Kits Test board
Thanks Erik, I reread the page I got that from and ya, I got it backwards.
" If S11=0 dB, then all the power is reflected from the antenna and nothing is radiated"
I see it now.
Thanks, Mikek
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Re: Back to Back transformer Measurement on SDR-Kits Test board
On Tue, Jun 9, 2020 at 09:07 AM, Mikek wrote:
I read that Ch0 10db/ -20.89db is the return loss, so, looking into the first
transformer,
it Is high (not 0db) because the 1.41uH is 8.9¦¸ at 1MHz and that causes most
of the -20.89 return loss?
Return loss is determined by how much the the thing connected to CH0 is deviating from pure 50ohm. The more perfect the thing, the higher the return loss (e.g. no echo from bad impedance matching) So -20dB is a very good match and indeed is measures 50.7¦¸ 1.41uH -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
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Back to Back transformer Measurement on SDR-Kits Test board
I have the Test board from SDR-Kits as shown in the Attachment.
I've had inconsistent results measuring two back to back 50 ohm to 100 ohm transformers.
At one point I measured -0.4db loss for two and now consistently -2.78db At 500kHz to -3.16db at 4MHz,for two transformers.
Does -1.5db loss for 10 turns wound over 7 turns on a #43 binocular core sound about correct, or would you expect lower?
Here's what the display reads,
Ch0 10db/ -20.89db Ch1 LogMag 10db/ -2.77db
CH0 Smith 1.0FS 50.7¦¸ 1.41uH CH1 Phase 90*/ -3.051*
1MHz
What I think I know about those numbers, is, if I divide the -2.77 in half, that is a single transformer's loss,
Looking into the first transformer it does look like 50.7¦¸ with just a bit of inductance at 1MHz..
Looks like a slight phase shift, maybe caused by that bit of inductance.
I read that Ch0 10db/ -20.89db is the return loss, so, looking into the first transformer,
it Is high (not 0db) because the 1.41uH is 8.9¦¸ at 1MHz and that causes most of the -20.89 return loss?
Is that correct?
I posted the Test board to verify my cal procedure.
Cal-Calibration
Insert open 7E to 7F, push- Open
Insert short 7E to 7F, push- Short
Insert 50 ohm 7E to 7F, push- Load
Insert 50 ohm 1E to 1F, push- Isolate
Install wire from D1 to D7, push- Thru
Push-Done
Push Back
Push Save
Pick a slot-Save1
When I finish the cal, with the thru wire still in, I have the following readings.
CH0 10db/ -48.46 CH1 LogMag 10db/ 0.00db
CH0 Smith 1.0FS 50.3¦¸ 5.71nH Ch1 Phase 30*/ -0.002
Anything I need to change?
What does CORRECTION do?
If it's in the wrong position I get 68db loss on my transformers, but I have no clue what it's doing.
I think I learned a lot while formulating my question! It forced me to look things up! :-)
Thank you for your help, Mikek
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Whose firmware are you using?
Edy555 and Hugen's firmware is more conservative and does not push the limits of the device.
DiSlord's firmware is cutting edge and pushes the device's capabilities.
You need to chose what you want - or just install the F/W from each and experiment to see which one your device works best with.
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On Tuesday, June 9, 2020, 9:50:06 a.m. EDT, Trevor Clarke <pythonpimp@...> wrote:
I've got a NanoVNA from Aliexpress so I'm not entirely sure who actually manufactured it but when I use the latest firmware to get the extended frequency range I see loads of noise in most of the UHF. I cal 2m and 70cm ranges (either as a single sweep or two different collections). Using either the build-in interface or NanoVNA saver I get a pretty flat 50ohm response on the 2m range (and expected responses with open and short) after calibration but the 70cm range is an unusable mess. The analog front ends don't have cans on them and I'm not sure if that's something installed on "official" hardware builds or is missing from my particular one. That's the obvious place I see for noise introduction. Is this a known problem? Ideas where the noise might be coming from? Should I build cans for the front ends and see if that helps?
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I've got a NanoVNA from Aliexpress so I'm not entirely sure who actually manufactured it but when I use the latest firmware to get the extended frequency range I see loads of noise in most of the UHF. I cal 2m and 70cm ranges (either as a single sweep or two different collections). Using either the build-in interface or NanoVNA saver I get a pretty flat 50ohm response on the 2m range (and expected responses with open and short) after calibration but the 70cm range is an unusable mess. The analog front ends don't have cans on them and I'm not sure if that's something installed on "official" hardware builds or is missing from my particular one. That's the obvious place I see for noise introduction. Is this a known problem? Ideas where the noise might be coming from? Should I build cans for the front ends and see if that helps?
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Re: Telling the good from the bad
For a nonaVNA-V2/SAA-2 there are in my relative unexperienced view two easy to do measurements that tell a lot about the performance (of course after calibration) 1: Connect the ports with a 60dB attenuator. If the S21 is nice and flat up to above 3.5GHz you can be happy. If you remove the connection and you see the S21 dropping (a lot) you can even be happier 2: Connect two 50 ohm loads to a Tee and connect the tee to port 1 (CH0). If the S21 is a constant 25ohm (+/- 1ohm) with a only a phase rotation with increasing frequency that you can remove by adding a port 1 delay you can be happy. If this pure rotation continues above 3.5GHz you can be very happy. -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
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Hi Dale,
Nice to know that:) I think it was Mark Twain who said "reports of my death were greatly exaggerated" :) When my father was around about 30 years old anther man with the same name and close in age was killed in a car wreck. People who knew my father were astonished when he walked into the coffee shop.
73,
Bill KU8H
bark less - wag more
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On 6/8/20 9:14 PM, Dale Miller wrote: On 6/8/2020 11:16 AM, Bill Cromwell wrote:
Hi,
There was a trade school franchise known as "RETS" for Radio Electronics Television School. I attended some of their classes then after my time in the Navy. I doubt they are still in business. Another franchise I knew about "CIE" is long out of business. Good luck with your search.
73,
Bill? KU8H
bark less - wag more
CIE is still in business.
I took there courses while I was in the Army back in the late 80's early 90's.
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The compiler toolchain puts things like date stamps into the binary files. Every time you build you will get a different file, and this is not a problem.
There are options to disable it, or you can convert the binary to a format that doesn't have the variable data, I recall (but it's been years since I wanted to do that).
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On 6/8/2020 11:16 AM, Bill Cromwell wrote: Hi,
There was a trade school franchise known as "RETS" for Radio Electronics Television School. I attended some of their classes then after my time in the Navy. I doubt they are still in business. Another franchise I knew about "CIE" is long out of business. Good luck with your search.
73,
Bill? KU8H
bark less - wag more
CIE is still in business. I took there courses while I was in the Army back in the late 80's early 90's. -- All the Best & 7 3s Dale Miller, KC2CBD Cookeville, Tennessee Putnam County TN ARES Emergency Coordinator Vice President Cookeville Repeater Association Ham Operator since 1997 (Extra) stpatrick2@... Registered Linux User: #317401 Linux since June 2003 Registered Ubuntu User #26423 -- -- All the Best & 7 3's Dale Miller, KC2CBD Cookeville, Tennessee Putnam County TN ARES Emergency Coordinator Vice President Cookeville Repeater Association Ham Operator since 1997 (Extra) kc2cbd@... Registered Linux User: #317401 Linux since June 2003 Registered Ubuntu User #26423
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On Mon, Jun 8, 2020 at 04:40 PM, Clifford Heath wrote: No. You just have to know *how* to look. Always asking before properly looking
is lazy.
People who know the answers get tired of helping lazy people, because they
know perfectly well that lazy people won't bother to *learn* the material
anyway, so they'll be back next week with a different request for help. Well said. Roger
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On Fri, Jun 5, 2020 at 10:51 AM, BruceN wrote: ... It reminds me of the day, way
back in the day, when I asked someone where I could find documentation
regarding the Unix operating system. This was before the Internet (over 50
years ago). If you worked on Unix over 50 years ago, I'd like to see the evidence of that. Unix was only created 50 years ago this year. It was certainly unavailable outside Bell Labs. <> When it became available, it came with full online manuals and source code. I know this, because I used those manuals and that source code to learn Unix, port it, and write new drivers. The answer was "you just gotta know". This was the wrong answer at any time. I learned Unix from reading the manuals and the source code, like everyone else in those days. The problem now is not a lack of information, but an excess of information, presented in many different forms. Not all those forms will suite all learning styles, and not all is equally correct and coherent. Then, as now, it is critical to learn how to learn - and that includes finding sources for the information you need that is presented at the right level and in the right way for you to make the next step. There are basic techniques for this, and you should learn them. Simple things like searching Wikipedia, often using what you find to formulate better search terms. When the answers to your questions are "read this wiki" or "read that wiki",
the answer is just the same as: "you just gotta know where to look". No. You just have to know *how* to look. Always asking before properly looking is lazy. People who know the answers get tired of helping lazy people, because they know perfectly well that lazy people won't bother to *learn* the material anyway, so they'll be back next week with a different request for help. Meanwhile, I'm going to take a pointer from this thread to improve my understanding of group delay.
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There are excellent textbooks available which cover basic theory in a very understandable way. Some even reinforce the textbook with companion videos. One I can recommend is by Neil Storey - "Electronics: A Systems Approach, 6th Edition "
Here are the relevant links to the book ...
Author site:
Amazon - preview book -
Watch the companion videos -
Roger
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Hi,
There was a trade school franchise known as "RETS" for Radio Electronics Television School. I attended some of their classes then after my time in the Navy. I doubt they are still in business. Another franchise I knew about "CIE" is long out of business. Good luck with your search.
73,
Bill KU8H
bark less - wag more
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On 6/8/20 8:22 AM, Lee wrote: Regarding "In the days before the Internet it was a real struggle to find a textbook or magazine article which covered a subject of interest. "
There is also an element of luck to find a textbook, magazine article or YouTube that works for each individual. The is so much information that you can find but often not at the level at which you can absorb it. Good teachers are probably good teachers when they can figure out what the student is misunderstanding and help them with a variety of explanations. Self study will always be prone to the student becoming blocked by something that simply re-reading the same text again does not fix.
In 1976 between my high school Jr and SR years I took some free summer school classes at the North St. Paul vocational school in the sequence they had for "Radio and Television Repair" where the instructional material was hands on and the theory was well explained. There I learned some circuit analysis including superposition and Thevenin resistance, Thevenin voltage sources and Norton current sources and the transformation between them.? The bench work that followed the theory was very well defined, and explained to well reinforce the theory. Anyone trying to self teach would do well by such course material.
I am a B. S Physicist who has a carrier in electronic circuit design and have been VERY well served by what I learned that summer.? I have in the past year or so contacted that school to ask if they have any record of who produced that instructional material but they do not.
I would love to get copies to share with the younger technicians with whom I work. When I asked them, they did not remember if they had been taught about Norton and Thevenin transformations. I can tell by how they talk about circuits that they think only in terms of voltage and a current source is alien to them.
Would anyone know who would have been publishing vocational school instructional material in the mid 1970s for Radio and Television Repair?
I do not think it was this:
-----Original Message----- From: Roger Need via groups.io
Sent: Friday, June 05, 2020 6:39 PM
To: [email protected]
Subject: Re: [nanovna-users] Definition of terms
On Fri, Jun? 5, 2020 at 01:53 PM, David Eckhardt wrote:
No, it isn't "you just gotta know".? Those of us who actually spend the
time and make the effort to find an engineering sound? reference online
which everyone can access to answer the question(s), simply mean to help
and give you a sound answer without your invoking any number of search
engines and avoiding snake oil so prevalent on the www.? Chances are we've
"been there, done that" in our training/careers.? There are sources online
that put things much clearer and more succinctly than our own wording.
Chances are, we know where to look for clear and concise and engineering
sound answers which all can access and learn if they choose to pursue the
URL's.
I agree with much of what you have said.? In the days before the Internet it was a real struggle to find a textbook or magazine article which covered a subject of interest.? Nowadays there is a plethora of material available including videos and online courses which can answer most questions with a little effort.
As a bench engineer and electronics/computer science teacher I found that one can only acquire and retain a solid technical? understanding by hands-on experimentation, personal study and investigation. Just receiving the answers to a question does not result in good retention of technical material.? As they say "no gain without a little pain".
This does not mean that folks like me and other knowledgeable members of this group do not want to help.? On the contrary most of us here to share and learn from each other.? But I hope that most with a question will at least Google a bit and try and read some of the excellent material available on the Internet before asking basic questions.
Roger Need
.
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Re: Telling the good from the bad
The best way to find out the quality of a device is to measure a previously known load / attenuator / antenna / filter and compare the result with what you should have received. If it matches, your device is working. I can not offer a better option.
For example, connect a 30 dB attenuator between ports 0 to 1. Look at what you see in the measurement, what is the noise level.
If everything matches perfectly, the appliance works. Try another attenuator.
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Dr. David Kirkby, Kirkby Microwave Ltd
Dale Miller - KC2CBD
Roger Need