Re: NanoVNA firmvare, compiled by DiSlord
#firmware
On Sun, May 10, 2020 at 02:39 PM, CT2FZI wrote:
From your findings, using 201 points what would be the best bw?
Would it make sense to calibrate using a lower bw and for daily usage increase the bw for the same frequency range?
========================================
Luis,
I used to calibrate at 30 Hz and then switch to a higher bandwidth during testing for best results. DiSlord's 0.8.4.6 -H4 firmware automatically changes to a 30 Hz bandwidth during calibration so it saves me a step.
DiSlord has optimized the firmware to the degree that 201 points is the standard setting for me. Some devices I test produce inconsistent results if I use too fast of a sweep rate. Being able to slow down the sweep rate by choosing a lower bandwidth is another feature of DisLord's firmware that I appreciate.
- Herb
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Re: NanoVNA firmvare, compiled by DiSlord
#firmware
On Wed, May 6, 2020 at 10:58 PM, hwalker wrote: =========================================================
Kurt,
The reply I sent to you in message
/g/nanovna-users/message/13118 regarding the patch DiSlord
made to the Hardware.py module of NanoVNA-Saver is how he created the
screenshot. You can also use the screenV.py script that Oristo posted.
Substituting the Hardware.py module in NanoVNA-Saver 0.2.2 with DiSlord's
patched HardWare.py will, in addition to grabbing screenshots from the
NanoVNA-H4, also allow you to grab 201 pts per segment and make use of the
lower bandwidiths in DiSlord's firmware modification.
- Herb
Hi Herb! From your findings, using 201 points what would be the best bw? Would it make sense to calibrate using a lower bw and for daily usage increase the bw for the same frequency range? Cheers and thanks in advance.
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Re: NanoVNA Saver 0.2.2-1 TDR curves values
Rudi,
NanoSaver uses FFT methods to compute what would happen if you sent an impulse (sharp voltage spike) down the attached line. One trace represents the computed reflection of that impulse from irregularities on the line, like poor connections or changes if line impedance (say, 50 ohms to 75 ohms). The other trace attempts to show the impedance of the line as a function of distance. Unfortunately, the impedance trace does not quite work properly yet: it always shows increasing impedance. A 50 ohm line follwed by a 75 ohm line will show the expected step up in impedance, but a 75 ohm line followed by a 50 ohm line does not show a step down, instead it shows a step up. The developers are working on correcting this.
The firmware on the NanoVNA itself does this correctly. See my message 12494 on how to set up the NanoVNA to show the reflection of a step wave into the cable and read out the impedance along the line.
--John Gord
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On Sun, May 10, 2020 at 04:49 AM, Rudolf Schaffer wrote:
Hello,
Very pleased to be accepted in this group.
My dumb 1st question: What is the 2 curves values i get when doing a TDR ?
Coaxial length is correctly displayed (i'm very satisfied with the accuracy)
but i'm not clear
with the 2 curves definitions.
Thank you for your help.
Best 73,
Rudi, HB9ARI
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Re: NanoVNA Saver 0.2.2-1 TDR curves values
Hi Larry,
Thank you for your kind message.
I will use these information to find an answer to
this 1st question and future too !
Best regards,
Rudi
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Le 10.05.2020 ¨¤ 16:33, Larry Rothman a ¨¦crit?: Hi Rudi,
Welcome to the forum!
Please use the WIKI and FILES sections - they contain a lot of good technical and practical information.
Use the search function as well on forum messages - search the hashtags.
There are a couple of printable manuals in the FILES section and links to several in the WIKI.
The user guide that I edit has a section on TDR and shows examples.
Refer to the links at the bottom of any forum email you receive.
Cheers,larry
On Sunday, May 10, 2020, 7:49:55 a.m. GMT-4, Rudolf Schaffer <rudolf.schaffer@...> wrote:
Hello,
Very pleased to be accepted in this group.
My dumb 1st question: What is the 2 curves values i get when doing a TDR ?
Coaxial length is correctly displayed (i'm very satisfied with the accuracy) but i'm not clear
with the 2 curves definitions.
Thank you for your help.
Best 73,
Rudi, HB9ARI
|
Re: Test fixture question
Your explanation agrees with my logic... There is a mistake in the
drawing attached, the 33 pF capacitors appear marked 33 nF, not 33 pF.
That?s it.
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On 5/9/20, hwalker <herbwalker2476@...> wrote: On Sat, May 9, 2020 at 11:34 AM, Bill Buoy wrote:
... "Now to the point of this. The capacitor value (33nF/0.033uF) seems very
large for use at all but very low frequencies. Virtually all of the similar
designs lack this capacitor entirely. So am I missing something?" ....
=============================================
I posted about the ACMP Xtal testing project using the NanoVNA at Github (
) a while back. Last change was about 4 month's ago so not much progress
since then.
According to the schematic posted at the Github (see attached) the fixture
presents a capacitive load of 19 pf with the values used.
- Herb
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Re: NanoVNA Saver 0.2.2-1 TDR curves values
Hi Rudi,
Welcome to the forum!
Please use the WIKI and FILES sections - they contain a lot of good technical and practical information.
Use the search function as well on forum messages - search the hashtags.
There are a couple of printable manuals in the FILES section and links to several in the WIKI.
The user guide that I edit has a section on TDR and shows examples.
Refer to the links at the bottom of any forum email you receive.
Cheers,larry
toggle quoted message
Show quoted text
On Sunday, May 10, 2020, 7:49:55 a.m. GMT-4, Rudolf Schaffer <rudolf.schaffer@...> wrote:
Hello,
Very pleased to be accepted in this group.
My dumb 1st question: What is the 2 curves values i get when doing a TDR ?
Coaxial length is correctly displayed (i'm very satisfied with the accuracy) but i'm not clear
with the 2 curves definitions.
Thank you for your help.
Best 73,
Rudi, HB9ARI
|
Re: Test fixture question
Hi Herb Thank you for the schematic As alan victor mentioned in the next comment here, the test fixture is in not to recommend as a general test fixture designed for one specific frequency as the Shunt C to the crystal will be frequency dependent. What this fixture is trying to accomplish is to measure the antiresonans frequency (the high one) and the series resonance and derive the crystal parameters thereof knowing the circuit components and including these in the calculation. I have done a lot of crystal measurement with the VNWA which have an function to measure the Rs, Ls Cs and Cp and deliverer the result in a spreadsheet for as many XTAL you like. No need for a 15 ohm test fixture at all just plain 50 ohm input output sources. For the VNWA you can use S11 or S21 as you wish. In general for S21 it is a good idea to insert 2x 10dB attenuator attached directly to the input and output of the test adaptor. I would be interesting to see how this application could be modified to cope with this setup. For high precision the VNWA has a feature to measure the crystal using S21 12 term error correction but that is only if you own a VNWA I have made a 50 ohm environment test adaptor Version 5 as seen on the images allowing to add shunt (e.g. 30pF) and series components L or C to shift the series resonance slightly. I also made an even more universal version 5. If anyone interested I have Eagle Layout and gerber files so PM me to kurt@... and I can send it Kind regards Kurt -----Oprindelig meddelelse----- Fra: [email protected] < [email protected]> P? vegne af hwalker Sendt: 10. maj 2020 00:46 Til: [email protected]Emne: Re: [nanovna-users] Test fixture question
On Sat, May 9, 2020 at 11:34 AM, Bill Buoy wrote:
... "Now to the point of this. The capacitor value (33nF/0.033uF) seems very large for use at all but very low frequencies. Virtually all of the similar designs lack this capacitor entirely. So am I missing something?" ....
=============================================
I posted about the ACMP Xtal testing project using the NanoVNA at Github ( ) a while back. Last change was about 4 month's ago so not much progress since then.
According to the schematic posted at the Github (see attached) the fixture presents a capacitive load of 19 pf with the values used.
- Herb
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Re: Test fixture question
Wouldn?t it rather be 33 pF, the standard parallell load for FT243 crystals?
73 de Jose, CO2JA
PS: In russian 33 §á§¶ is 33 pF... just in case...
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On 5/9/20, Kurt Poulsen <kurt@...> wrote: Hi Bill
Sound as an interesting project. I visited the gitbug and found not much
description about the text fixture. I suppose you found it via KiCad. It
must be a bug it will not work up 150MHz as claimed.
I did such an test fixture years ago
Test Fixture for DG8SAQ VNWA and N2PK
VNA.pdf
And calibrated at the DUT position not and not as I think the gitbug
application does in the input/output side which introduces error as the two
attenuators are included and not without amplitude variation and phaseshift
variation over the frequency range. However is the application (as said
there is not much info how to use the application) is measuring S21 only and
calibration done by a shorting wire substituting the DUT then attenuators
are waved and part of the calibration. Then watch out as isolation should
not be done neither SOL.
That is what I can conclude but let me hear what you experience or have you
found a usage guide for the gitbug application.
Kind regards
Kurt
-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Bill
Buoy
Sendt: 9. maj 2020 20:35
Til: [email protected]
Emne: [nanovna-users] Test fixture question
I am building a test fixture for use with my nano-VNA. The primary purpose
is to test/characterize a group of crystals for use in a crystal ladder
filter in a couple of receiver projects I am using to stay busy through this
crazy time we are experiencing. It is based on a simplified version of the
IEC444 fixture as implemented by AE1C.
One of the suggested fixtures is found on github, in the project by
Battosai42. In the supporting hardware for his amcp program, the impedance
matching is done with a pi attenuator as shown in the (crude) text schematic
below. For simplicity, only the input side is shown. The output is a mirror
image.
O----+-----( 66.2 ohms )-----+---------------------+------[DUT]--
| | |
| | |
(159 ohms) (14.2 ohms) (33 nF)
| | |
| | |
O---+-----------GND-----------+---------------------+----------------
Now to the point of this. The capacitor value (33nF/0.033uF) seems very
large for use at all but very low frequencies. Virtually all of the similar
designs lack this capacitor entirely. So am I missing something? I have seen
nothing of this in other designs discussed on the web, in QEX, or other
discussions. Perhaps someone here can enlighten me, as well as the group.
Thanks for your consideration.
73,
Bill
P.S.
As soon as the design is complete, I plan to post the files here and make
the boards available through OshPark.
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NanoVNA Saver 0.2.2-1 TDR curves values
Hello,
Very pleased to be accepted in this group.
My dumb 1st question: What is the 2 curves values i get when doing a TDR ?
Coaxial length is correctly displayed (i'm very satisfied with the accuracy) but i'm not clear
with the 2 curves definitions.
Thank you for your help.
Best 73,
Rudi, HB9ARI
|
Don't know anything about Hugen, but the GigaParts "-H" is a good one.
Comes with all the accessories, including installed battery.
$69 USD I think.
*Bob Kircher, K7QXY*
Tigard, OR
(503) 789-3983 (cell)
Please be sure your contacts lists show kircherbob@... for my address.
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On Sat, May 9, 2020 at 5:58 PM Birdman <ccarrara@...> wrote: On Fri, May 8, 2020 at 03:15 PM, Paul W8SBH wrote:
My "H" model from Gigaparts seems to be what you are looking for. T
--
Paul
W8SBH Wow, Gigaparts is carrying the new one? Is that the actual Hugen built
unit?? or just a good knockoff....? or?
Thanks
--
Regards,
Chris
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Re: Test fixture question
I use a crystal test fixture that I built for the Poor Ham Scalar Network Analyzer (PHSNA) and I used it very much with good success with the nanoVNA also. It consist on two 50 to 12,5 Ohm broadband transformers with resistive attenuators at both ends to insure correct loading and adequate drive level for the crystal. It could be useful to have the capability of replacing the crystal with a variable resistor, either with a switch or a plug in resistor, to find the equivalent series resistance, but it could be calculated with the appropriate functions included in the the software / firmware without that resistor. I have been talking with the nanoVNA Saver author about this and he plans to include specific crystal measurement functions in a future version. The PHSNA group is plenty of these test fixtures. An example is here: /g/PHSNA/files/Crystal%20Test%20Fixture/Crystal%20Test%20Fixture%20Overview.pdfI built mine without the optional amplifier and without the variable resistor also, so I did it without a PCB, just the input and output connectors, a socket for the crystal, the transformers and the two Tee pads. If anyone is interested I can upload info and pictures to the group. Regards, Ignacio? EB4APL
El 10/05/2020 a las 2:20, alan victor escribi¨®: It appears that this fixture is specific to the crystal under investigation. The fixture is providing a total load R of 25 ohms series from each side. Is possible if you transform the shunt C to its series equivalent from each side of the fixture, the total C load is 19 pF. A check on this requires knowing the test frequency. Seems like a stretch but you need to check if that is the case by transforming the network from its parallel to series form.
If you desire to build a general purpose test set for xtals, and obtain their parameters, this fixture is inappropriate. You can stay in the 50 ohm system or to improve measurement accuracy, transform 50 ohms to a lower Z. Either 12.5 or 6.25 ohms is done with a transformer. Hence loss, S21 will get you Rs from a voltage divider and loaded Q is obtained from a 3 dB BW measure, hence unloaded Q is obtained from the 20 log ratio of Q's and loss. The motional L and C parameters as well the holder C are obtained from some additional freq response measures.
Alan
--
El software de antivirus Avast ha analizado este correo electr¨®nico en busca de virus.
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Hi tuckvk3cca
I had that problem before; I set up the smith chart on the left hand side.
I looks to me like the square shape of the smith chart does not line up
properly
with the right hand edge, so that it tries to align that side, but can't
b/c the edges don't line up.
Cheers
Colin
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On Sun, 10 May 2020 at 06:39, Paul Brodie <techo@...> wrote: On Sat, May 9, 2020 at 09:49 AM, tuckvk3cca wrote:
Nanovna Saver
Try an earlier version of Nanovna Saver.
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Hi Truck, there may be a problem with the operating system, such as the screen size you choose or the frame rate you choose. If this helps, check to see if the /g/nanovna-users/message/10419 post is up on your machine. NanoVNA-Saver requires a minimum of windows7 because VC ++ can be installed on it. You can see what is installed among the installed files. What you need is in it: I hope it helps in the solution 73, Gyula HA3HZ -- *** nothing is permanent only change ( ) ***
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Re: Test fixture question
My guess is the 33 nF is 33 pF, a typo. Transfer to a series may give 39 pF and hence the double loaded C is 19 pF. Again the fixture is specific and not generic test set.
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On Fri, May 8, 2020 at 03:15 PM, Paul W8SBH wrote: My "H" model from Gigaparts seems to be what you are looking for. T
--
Paul
W8SBH Wow, Gigaparts is carrying the new one? Is that the actual Hugen built unit?? or just a good knockoff....? or? Thanks -- Regards, Chris
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Re: TDR setup for NanoVNA
#tdr
I want to compliment whomever created the NanoVNA TDR firmware additions. I started with the the NanoVNA-Saver TDR and became confused because it does not work the way that I remembered a TDR should work. So I went into the basement and made my own very simple "poor-man's TDR" with a reed relay driven by an old function generator, a 50 ohm resistor, a used D cell battery and a 15 year old 300 MHz digital oscilloscope. This worked great and would easily give me the characteristic impedance and length of various pieces of coax that I had in the basement and with the different terminations. As Herb Walker has mentioned there is still some work to be done debugging the TDR of NanoVNA-Saver so I started testing the NanoVNA-H4 firmware TDR. It took me a little while to independently come up with the setup that John Gord very correctly stated in /g/nanovna-users/message/12494 , but once I understood how to set things up I became very pleased. After many tests, I was convinced that the NanoVNA-H4 TDR firmware worked exactly like my poor-mans TDR for every configuration of loads. I even found a small capacitive discontinuity in the middle of a 200 foot length of 75 ohm buried coax. Both the NanoVNA-H4 TDR and the poor-mans TDR agreeded perfectly on the location and the magnitude of this discontinuity. Looks like the lawn care crew drove a heavy lawn mower over the cable and compressed it a bit. Thank you for doing a great job on the NanoVNA TDR firmware--whomever you are!!! Larry Weber K9ZBU
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Re: Test fixture question
It appears that this fixture is specific to the crystal under investigation. The fixture is providing a total load R of 25 ohms series from each side. Is possible if you transform the shunt C to its series equivalent from each side of the fixture, the total C load is 19 pF. A check on this requires knowing the test frequency. Seems like a stretch but you need to check if that is the case by transforming the network from its parallel to series form.
If you desire to build a general purpose test set for xtals, and obtain their parameters, this fixture is inappropriate. You can stay in the 50 ohm system or to improve measurement accuracy, transform 50 ohms to a lower Z. Either 12.5 or 6.25 ohms is done with a transformer. Hence loss, S21 will get you Rs from a voltage divider and loaded Q is obtained from a 3 dB BW measure, hence unloaded Q is obtained from the 20 log ratio of Q's and loss. The motional L and C parameters as well the holder C are obtained from some additional freq response measures.
Alan
|
Re: Test fixture question
On Sat, May 9, 2020 at 11:34 AM, Bill Buoy wrote:
... "Now to the point of this. The capacitor value (33nF/0.033uF) seems very large for use at all but very low frequencies. Virtually all of the similar designs lack this capacitor entirely. So am I missing something?" ....
=============================================
I posted about the ACMP Xtal testing project using the NanoVNA at Github ( ) a while back. Last change was about 4 month's ago so not much progress since then.
According to the schematic posted at the Github (see attached) the fixture presents a capacitive load of 19 pf with the values used.
- Herb
|
Re: [nanoVNA] A practical case identifying ferrite materials
In the same spirit of sharing, let me also share this wonderful software developed by DL5SWB:
"Using the mini Ring Core Calculator application will make it easier for amateur radio enthusiasts to calculate inductors, numbers of turns, wire lengths, and many other factors related to both powdered iron and ferrite toroids. In addition, the program will also enable you to calculate parameters for air wound coils used in the construction of linear amplifiers, low pass filters and antenna matching units."
Free!!!!
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CT2FZI
Jose Amador
Kurt Poulsen
Bob Kircher
Gyula Molnar
Chris K2STP
