Re: New owner of nanovna-H and H4, However pondering the next step in precision
Siegfried Jackstien - Thanks for the recommendation, I will research these.
John Gord - Re maintaining a consistent length between O, S, L - the three now provided with the nanoVNA are just RPSMA caps... therefore they should meet this criteria?
Thanks for the details on the article, Should be able to find it.
Donald S Brant Jr - Thanks for the recommendation, I'll research LibreVNA
Also, you're right re making your own...a matter of confidence vs doubt... I guess buying multiple kits then testing them all to see the alignment may help put faith in the chosen kit?
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
Don't downplay the accuracy of the NANOVNAs. I have compared several offerings from the NANOVNAs with the HP 8753C with the associated S-Parameter test set using HP cal. standards. The agreement, within each other's limitations, is astounding. Sure, the cal. standards that come with the NANOs are not the quality of those from HP, but not bad at all, especially in the HF to low VHF range. I seriously doubt you will find anything more "accurate" within your targeted price range. If you want to increase your upper price limit to $10 or $12 killobucks, then, yes, you can do better. You "might" find a used 8753C, but beware. I have a friend who went that route for $4k, and the display does not behave properly. Dave - W?LEV On Thu, Aug 4, 2022 at 4:30 AM Siegfried Jackstien < siegfried.jackstien@...> wrote: KC901
Different range (and so price) available
Between 1000 and 2000 bucks or so
Much more professional and accurate as all the Nanos... And still portable
use (with a bit bigger display)
So i recommend those if you really want to spent more for a better unit
Dg9bfc sigi
Am 04.08.2022 03:32 schrieb "0root via groups.io" <hntpro@...
:
Hi John
Good guess at both my range of interest(indeed below 900MHz) and the
education side... I have very limited techniques as im new to it all.
Im going to try and find that article you mention, if not il try to buy
an
old hard copy of the mag on ebay.
Re the loads, you are referring to the three calibration connectors
provided correct?
Would making my own finer tuned ones be a realistic task? as in
components, pricing, and skill?
If not if you know anywhere to buy some finer tuned I would appreciate the
link
Thanks for the help!
-- *Dave - W?LEV* *Just Let Darwin Work* -- Dave - W?LEV
|
Re: At which point do we take the value of impedance to tune an antenna?
On Thu, Aug 4, 2022 at 05:32 AM, Arie Kleingeld PA3A wrote: Lets put it simple without too many formulas. There has been a lot of
math to come to the SWR formulas but we can think about it. Lots of things to tell about that subject. The following might be
interesting for you:
Arie, Thank you for posting your paper. I suggest that you correct the text below to state that this formula is only true when the reactance X is 0. I have seen on many occasions people thinking that the magnitude of impedance |Z| can be used in this formula. For example if the complex impedance is 40 + j30 then |Z| =50 and the SWR is 2.0 (when the reference impedance is 50 +j0 ohms). Someone misusing the formula would think |Z|/50 = 1.0 for the SWR which is incorrect. Roger
|
Re: At which point do we take the value of impedance to tune an antenna?
On Wed, Aug 3, 2022 at 06:52 PM, Kenneth Hendrickson wrote: On both charts, 25+j0 and 100+j0 need to be swapped. They are wrong as
labeled.
Thanks for the correction. I put these together quickly and should have proofread them for errors. Here are the corrected versions showing several complex impedance values that all result in an SWR of 2.
|
Re: At which point do we take the value of impedance to tune an antenna?
Hi Russ,
Lets put it simple without too many formulas. There has been a lot of math to come to the SWR formulas but we can think about it.
The reflection coefficient is the percentage of reflected voltage from a load. From that and the still going forward voltage we get those standing waves. At some points along the transmissionline the voltages add-up, at other points the substract. If we measure the ratio of the substracted voltages and the added voltages then we get the SWR.
So: From voltages as you well stated.
In the general case the reflectioncoefficient can be a percentage plus an phase shift. That is what the Smith chart shows.
Lots of things to tell about that subject. The following might be interesting for you:
the first ten pages of this presentation will tell you what you want to know.
73
Arie PA3A
Op 3-8-2022 om 17:52 schreef Russ:
toggle quoted message
Show quoted text
On Tue, Aug 2, 2022 at 05:26 PM, Jerry Stuckle wrote:
The VSWR is based on impedance - which is a combination of resistance and
reactance.
Can you explain this in more detail. I thought VSWR was based on voltage.
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
You can certainly make a homemade short or open, but characterizing it accurately is another thing entirely. Without accurate characterization a standard is useless.
73, Don N2VGU
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
I am happy with my LibreVNA, but I also bought a better calibration kit than was provided. The quality of the kit and accuracy of the standards' characterization will directly affect the accuracy of the results. I use it in my professional practice, most recently to characterize a MIL SATCOM IF processing unit I designed for a client for a client. Jan's software support is excellent and he is making ongoing improvements.
73, Don N2VGU
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
Oroot,
At frequencies up to 1GHz or so, it is certainly practical to make your own Open, Short, and Load. Ideally, the three standards should be the same length, which becomes more critical at higher frequencies because the wavelength gets shorter.
Search for something like "homemade 50 ohm load vna" to get some ideas on what others have done.
The QEX article is available online to ARRL members. Perhaps a nearby friend who is a member could print the article for you. Failing that, the author of the article is Gary Cobb, and his email is g3tmg@.... He might be willing to email you a copy of the article. The title is "Improved Low-loss Measurements with a NanoVNA".
--John Gord
toggle quoted message
Show quoted text
On Wed, Aug 3, 2022 at 06:32 PM, 0root wrote:
Hi John
Good guess at both my range of interest(indeed below 900MHz) and the education
side... I have very limited techniques as im new to it all.
Im going to try and find that article you mention, if not il try to buy an old
hard copy of the mag on ebay.
Re the loads, you are referring to the three calibration connectors provided
correct?
Would making my own finer tuned ones be a realistic task? as in components,
pricing, and skill?
If not if you know anywhere to buy some finer tuned I would appreciate the
link
Thanks for the help!
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
Correction
Between 1400 and 4000
But that one goes to 20 gig hz!!!
Greetz sigi dg9bfc
Am 04.08.2022 06:30 schrieb Siegfried Jackstien <siegfried.jackstien@...>:
toggle quoted message
Show quoted text
KC901
Different range (and so price) available
Between 1000 and 2000 bucks or so
Much more professional and accurate as all the Nanos... And still portable
use (with a bit bigger display)
So i recommend those if you really want to spent more for a better unit
Dg9bfc sigi
Am 04.08.2022 03:32 schrieb "0root via groups.io"
<hntpro@...>:
Hi John
Good guess at both my range of interest(indeed below 900MHz) and the
education side... I have very limited techniques as im new to it all.
Im going to try and find that article you mention, if not il try to buy
an
old hard copy of the mag on ebay.
Re the loads, you are referring to the three calibration connectors
provided correct?
Would making my own finer tuned ones be a realistic task? as in
components, pricing, and skill?
If not if you know anywhere to buy some finer tuned I would appreciate the
link
Thanks for the help!
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
KC901
Different range (and so price) available
Between 1000 and 2000 bucks or so
Much more professional and accurate as all the Nanos... And still portable use (with a bit bigger display)
So i recommend those if you really want to spent more for a better unit
Dg9bfc sigi
Am 04.08.2022 03:32 schrieb "0root via groups.io" <hntpro@...>:
toggle quoted message
Show quoted text
Hi John
Good guess at both my range of interest(indeed below 900MHz) and the
education side... I have very limited techniques as im new to it all.
Im going to try and find that article you mention, if not il try to buy an
old hard copy of the mag on ebay.
Re the loads, you are referring to the three calibration connectors
provided correct?
Would making my own finer tuned ones be a realistic task? as in
components, pricing, and skill?
If not if you know anywhere to buy some finer tuned I would appreciate the
link
Thanks for the help!
|
Re: Launch of a new product by Deepelec (DeepSDR 101)!
Hello,
I did a surch the project,
:
DeepSDR Radio DSP Digital Demodulation Shortwave AM FM MW SSB CW HAM Receiver
Clyde KC7BJE
|
Re: At which point do we take the value of impedance to tune an antenna?
On both charts, 25+j0 and 100+j0 need to be swapped. They are wrong as labeled.
toggle quoted message
Show quoted text
On Wednesday, August 3, 2022, 06:42:32 PM EDT, Roger Need via groups.io <sailtamarack@...> wrote:
Time is well spent learning a bit about the Smith Chart.
You can plot a complex? impedance and then draw a circle that intersects the point and get the SWR.? You can also measure the distance and get the reflection coefficient and gamma.
A picture is worth a thousand words so here is a plot on a Smith Chart of several complex impedances that all result in a SWR of 2 and a reflection coefficient of 0.333 ( a Reflection Loss of 9.54 dB).? The 40 + j30 from the earlier discussion is one of these.
Roger
|
Re: Launch of a new product by Deepelec (DeepSDR 101)!
Kadir, what does it offer that nanovna-h doesnt?
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
Hi John
Good guess at both my range of interest(indeed below 900MHz) and the education side... I have very limited techniques as im new to it all.
Im going to try and find that article you mention, if not il try to buy an old hard copy of the mag on ebay.
Re the loads, you are referring to the three calibration connectors provided correct?
Would making my own finer tuned ones be a realistic task? as in components, pricing, and skill?
If not if you know anywhere to buy some finer tuned I would appreciate the link
Thanks for the help!
|
Re: Launch of a new product by Deepelec (DeepSDR 101)!
I, for one, really appreciated hearing about this new product although it may have been in the wrong forum.
I don't know where else Kadir might have announced it that I would have seen it. Perhaps there is an SDR forum for such news.
Doug.
toggle quoted message
Show quoted text
On 03/08/2022 21:13, Kadir Mari?o Abreu wrote: I apologize for the inconvenience caused, it will not be repeated, thank you.
-- */If you forward this email, please delete the forwarding history which also includes my email address. When sending emails, please BCC so as to hide all addresses. Thanks for helping to prevent Scammers and Spammers from mining addresses and spreading viruses./ 73 Doug Kearney VA3DKA * *Ottawa, ON *
--
This email has been checked for viruses by Avast antivirus software.
|
Re: Launch of a new product by Deepelec (DeepSDR 101)!
I apologize for the inconvenience caused, it will not be repeated, thank you.
|
Re: New owner of nanovna-H and H4, However pondering the next step in precision
Oroot,
Assuming the frequency range of interest is 900MHz and below, your best investment for better accuracy in RL/VSWR and attenuation is probably educating yourself in best technique.
As an example, the recent QEX magazine (July/Aug 2022) has an article on using the NanoVNA to accurately measure low loss devices like short cables and RF relays.
Another investment might be in a better Load standard for the connector type you use most. The supplied standard load is fine for most purposes, but for measuring very high RL the NanoVNA is capable of taking advantage of a better load. You can probably make your own Short and Open for any connector type you use at HF/VHF/UHF frequencies.
--John Gord
toggle quoted message
Show quoted text
On Wed, Aug 3, 2022 at 04:55 PM, 0root wrote:
Hey all, first post here.
I currently own and love the nanovna-h and h4, I was sure to buy them from the
alibaba store zeenko as this is apparantly hugens chosen manufacturer.
However, if I wanted to get more precision - specifically in the areas of
Return Loss / VSWR and attenuation readings - what would be the next device up
to get - within the region of $100 - $2000 and no higher...
I see alot of siglent stuff, but the reviews are not too appetizing
|
Re: At which point do we take the value of impedance to tune an antenna?
An excellent learning tool by just jumping in is SimSmith: There is also an excellent tutorial (and a lot more) by W?QE at: Dave - W?LEV On Wed, Aug 3, 2022 at 10:42 PM Roger Need via groups.io <sailtamarack= [email protected]> wrote: Time is well spent learning a bit about the Smith Chart.
You can plot a complex impedance and then draw a circle that intersects
the point and get the SWR. You can also measure the distance and get the
reflection coefficient and gamma.
A picture is worth a thousand words so here is a plot on a Smith Chart of
several complex impedances that all result in a SWR of 2 and a reflection
coefficient of 0.333 ( a Reflection Loss of 9.54 dB). The 40 + j30 from
the earlier discussion is one of these.
Roger
-- *Dave - W?LEV* *Just Let Darwin Work* -- Dave - W?LEV
|
New owner of nanovna-H and H4, However pondering the next step in precision
Hey all, first post here.
I currently own and love the nanovna-h and h4, I was sure to buy them from the alibaba store zeenko as this is apparantly hugens chosen manufacturer.
However, if I wanted to get more precision - specifically in the areas of Return Loss / VSWR and attenuation readings - what would be the next device up to get - within the region of $100 - $2000 and no higher...
I see alot of siglent stuff, but the reviews are not too appetizing
|
Re: At which point do we take the value of impedance to tune an antenna?
Time is well spent learning a bit about the Smith Chart.
You can plot a complex impedance and then draw a circle that intersects the point and get the SWR. You can also measure the distance and get the reflection coefficient and gamma.
A picture is worth a thousand words so here is a plot on a Smith Chart of several complex impedances that all result in a SWR of 2 and a reflection coefficient of 0.333 ( a Reflection Loss of 9.54 dB). The 40 + j30 from the earlier discussion is one of these.
Roger
|
Roger Need
Arie Kleingeld PA3A
Donald S Brant Jr
Clyde Lambert
