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Re: NanoVna Parts
Is true its handy to have that switch working, but you can still fully
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operate the nanovna without it. Everything from the touchscreen can be done, including drag and drop the markers... Cheers! LL On Thu, 8 Aug 2019 at 10:21, <jimcking@...> wrote:
Anyone know where to get parts for these. I broke the Multifunctional |
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Re: Annotated nanoVNA menu diagram
Hi Oristo
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This looks great! Really helpful. I have spotted a couple of differences between it and what I'm seeing with the 2 trace antenna analyser firmware on my Nano. I believe the 2 trace version uses a clearer larger font, so the format menu structure is slightly different. Here's what I'm seeing on my Nano: The Trace menu only has Trace 0 and Trace 1. The Format menu ends with "More" directly after "SWR". Clicking the "More" button brings up another menu with "Polar" & "Linear" on. With "Reference position" my default setting is shown as 7 000 for LOGMAG and changing it to 8 000 moves the trace reference (shown by a small marker at left of screen) up one grid space, to the top of the screen. With SWR the trace is off the bottom of the screen when 1:1. Changing the reference position to 180 brings the trace up onto the bottom of the screen. Regards Mike On Thu, 8 Aug 2019, 00:52 Oristo, <ormpoa@...> wrote:
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Re: Measurement challenge
Fahnestock clips take me back to Jr. High School Electric shop, where I got my ham radio license in 1956.
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Stuart. K6YAZ On Aug 7, 2019, at 6:27 PM, Larry Rothman <ac293@...> wrote: |
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Re: Battery size
Hello All !
with my unit the charging is limited to just under 500ma regardless even tho the charger is I am using is good for twice that much. So far I am pretty impressed with this little gizmo ! Next step is to compare how close the measurements are with my 8711 & 8712. got a good deal on my nano, $49 with free shipping ! 73 N8AUM |
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Re: Problem with shorts and load in cal kits
Dave,
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I solved this to some extent by cutting screwdriver slots in the back of the short and load, allowing the contacts to be held (somewhat) steady while the nut is tightened. It is a bit awkward to co-ordinate everything while tightening. I am thinking of soldering a lever arm to the back of the short to provide a better handle, but that might not be such a good idea for the load with its unknown internal construction. --John On Wed, Aug 7, 2019 at 03:23 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:
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Re: Some basic load measurements
The error mathematics for a one port VNA measurement with SOL is interesting to investigate. Given the assumption that the short and load are handled as ideal with reflection coefficients of -1 and 1, then a finite return loss load is considered. The effect of the finite return loss on the accuracy of the measurement is most pronounced as the DUT has a gamma approaching zero! In other words as you attempt to measure a device which is MATCHED the measurement error rises significantly. If you expect to measure devices say within a SWR circle of 1.5:1 or greater, you may be working very hard to obtain an improvement that is very minuscule. Most of the devices I believe we generally encounter do not have return losses less than 20 dB. I'll see if I can find or provide the mathematics behind this premise.
Alan |
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Re: Some basic load measurements
There appears to be TWO different loads provided with the NanoVNA instrument. I reported this in an earlier message. The 50 ohm termination with the white gecko unit was pretty poor and demonstrated a 18 dB return loss at 900 MHz. That has since been degraded to 16 dB after about 3 weeks of using it. When I first measured it NEW it showed a series inductance of approximately 500 pH.
The termination kit 50 ohm with the black VNA unit is considerable better. I measured about 44 dB RTL across the 50 kHz to 900 MHz range. I would consider that quite good. Again as a point of reference, the APC -7 precision connectors provided by Keysight are 53 dB return loss DC-to- 5 GHz. These are the so called sexless connector. Very nice. I think you should be pleased with a 40 dB + RTL. Far more important, after you find such a wonderful and precise load, take care of it. As soon as you use it and if you allow the center pin to rotate just ONCE, your return loss will be shot! A bit of gold will be scraped off the center pin to rest upon the dielectric. Do that a few times and watch the trail of parasitic L/C begin to build. The return loss is out the window. Regards, Alan ________________________________ From: [email protected] <[email protected]> on behalf of Peter Gottlieb <hpnpilot@...> Sent: Thursday, August 8, 2019 1:52 AM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Some basic load measurements I made some further measurements using the 8753 setup. I did the OSL cal on one port and looked at both the Smith chart as well as S11. I didn't bother with the cheap BNC load. I used averaging (16) to get more stable measurements. The Smith chart was of little use as each load showed up as a tiny one pixel dot almost exactly in the middle. However, it does display reactance values. All the values here are from the 8753. Load R Z contrib ohms value S11 @ 900 MHz OSL 50.000 0.0000 0.0000 H -76 dB (noisy) Nano 49.184 0.4255 76.942 pH -40.673 dB Narda 50.438 -33.203 m 5.3205 nF -47.356 dB Tiny 49.389 0.5977 105.58 pH -40.678 dB Note the resistance values on the 8753 differ from the DC resistance somewhat, even normalizing to the OSL value. You can clearly see the OSL becomes the definition of 50 ohms and the S11 is at the analyzer noise floor. tuckvk3cca pointed out how the 1.02 SWR corresponded to a 40 dB return loss and he is spot on. The Narda shows the best return loss at 900 MHz of better than 47 dB. What would be considered a high quality load? The one that comes with the NanoVNA is not terrible considering the other tiny one I have, which has a NSN number on it, is very similar. Not that having a NSN number infers anything spec particular, but at least it will have a minimum set of specs so somebody thought about it. I note that the very small SMA terminations are slightly capacitive while the 1.5" long Narda termination (it probably has some power rating) is slightly inductive. These variations are too small to see on the Smith chart at regular scale. Peter On 8/6/2019 10:43 PM, Peter Gottlieb via Groups.Io wrote: Resending from website as it didn't seem to go through as a message. Also my pasted table from Excel lost formatting so I tried to fix it to be more readable. |
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Re: Measurement challenge
Wow, I have not seen those since I was a child, say age 13!
Yes, I suppose they would work fine! What I had in mind and what I am currently having pretty good success with is a Pomoma grabber cable to a BNC connector. I am calibrating in a BNC environment. I adapt from SMA to BNC. Built a BNC short, open and have a commercial hp 50 ohm termination. Not pretty, but 50 kHz to 30 MHz so far reasonably effective. I will try to photo the test set and results. [cid:42067b24-ec64-4b89-9b13-5fef48015439] ________________________________ From: [email protected] <[email protected]> on behalf of Larry Rothman <ac293@...> Sent: Thursday, August 8, 2019 1:27 AM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Measurement challenge Alan, Alligator clips are so yesterday... I've got some great Fahnestock clips for you! ;-) |
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Test drivers wanted.
Anybody wish to volunteer to perform the task of loading and comparing firmware¡¯s and/or versions/release levels?
It would be nice to avoid the judgmental pitting of one against any all others; so I think what is needed and most welcomed by most of us at this stage of our collective level of knowledge and understanding; is a general, but informed, overview with useful comments of how each behaves... not a detailed blow by blow walk through of every operation. The intent is to establish a sense of stability (bugginess), ergonomic improvements, feature adds/changes, and general user observations to guide users with meaningful and relevant information when assessing if and when a change or upgrade might better serve their own needs. Not doing so relegates the task to all of us flailing through the exercise on our own. The redundancy of this approach is likely to escalate into multiple divergent and opinionated threads causing the task of making an informed decision unachievable. That said... If you feel you can take this on before we become overwhelmed with firmwares coming at us from every direction, you will certainly be of high value to the group; both by those that are new to VNA¡¯s, and those who are seasoned, experienced, and most able to contribute in a focused manner to educate and advance our understanding and utility of the NanoVNA in particular, and VNA¡¯s in general. -- 73 Gary, N3GO |
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Re: Some basic load measurements
I made some further measurements using the 8753 setup.
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I did the OSL cal on one port and looked at both the Smith chart as well as S11. I didn't bother with the cheap BNC load.? I used averaging (16) to get more stable measurements. The Smith chart was of little use as each load showed up as a tiny one pixel dot almost exactly in the middle.? However, it does display reactance values. All the values here are from the 8753. Load??????? R??????????????? Z contrib ohms???? value S11 @ 900 MHz OSL???????? 50.000????????? 0.0000???????????????? 0.0000 H -76 dB (noisy) Nano????? 49.184????????? 0.4255???????????????? 76.942 pH -40.673 dB Narda???? 50.438 ? ? ?? -33.203 m? ?????????? 5.3205 nF -47.356 dB Tiny??????? 49.389 ???????? 0.5977 ???????????????? 105.58 pH -40.678 dB Note the resistance values on the 8753 differ from the DC resistance somewhat, even normalizing to the OSL value.? You can clearly see the OSL becomes the definition of 50 ohms and the S11 is at the analyzer noise floor. tuckvk3cca pointed out how the 1.02 SWR corresponded to a 40 dB return loss and he is spot on.? The Narda shows the best return loss at 900 MHz of better than 47 dB. What would be considered a high quality load?? The one that comes with the NanoVNA is not terrible considering the other tiny one I have, which has a NSN number on it, is very similar.? Not that having a NSN number infers anything spec particular, but at least it will have a minimum set of specs so somebody thought about it. I note that the very small SMA terminations are slightly capacitive while the 1.5" long Narda termination (it probably has some power rating) is slightly inductive.? These variations are too small to see on the Smith chart at regular scale. Peter On 8/6/2019 10:43 PM, Peter Gottlieb via Groups.Io wrote:
Resending from website as it didn't seem to go through as a message. Also my pasted table from Excel lost formatting so I tried to fix it to be more readable. |
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Re: Problem with shorts and load in cal kits
Dr. David Kirkby from Kirkby Microwave Ltd
On Thu, 8 Aug 2019 at 02:08, Gary O'Neil <n3go@...> wrote:
Good observation Dave; Yes, I had thought about a video on that. I have a video camera, but since I am a Unix person I had problems getting the data off of the card reader. I tried a virtual machine, but that didn¡¯t work. I only have the one video on YouTube, which I took with my mobile whilst doing the task and fighting hayfever. Connector savers will not impact the calibration quality, whereas any attempt to improve the mechanical properties of the short will cause problems Dave -- Dr. David Kirkby, |
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Re: Problem with shorts and load in cal kits
Good observation Dave;
Alan¡¯s suggestion to use SMA Male-Female adapters to protect the connectors on the NanoVNA would be prudent also. Both also give us something to scrounge for and haggle a bargain at our next hamfest. :-) The care and feeding of RF connectors in general might be a useful topic for your next YouTube video. As you know improper use of RF connectors can be equally destructive as using connectors of marginal quality. -- 73 Gary, N3GO |
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Re: Annotated nanoVNA menu diagram
Looks real good. I think it needs a button to get you back to the main page. I guess the browser back is the only way to do that
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Thanks Frank On 8/7/2019 8:09 PM, Stuart Landau via Groups.Io wrote:
Terrific addition to our knowledge of the NanoVNA. |
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Re: Measurement challenge
Or turn that around: how sloppy can you be with HF construction techniques and still have reasonable results?
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Peter On Aug 7, 2019, at 8:29 PM, alan victor <avictor73@...> wrote: |
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Re: Measurement challenge
Yes, that is an excellent test. If you make use of a somewhat narrow sweep so with 101 data points you can obtain the required resolution, you can find the +/- 45 degree phase shift points for S21. This will pull out the -3 dB bandwidth. I'll have to see if I can conduct such a test.
However, for now I have been conducting a much simpler measurement challenge. That is after CAL, obtaining a reasonable accurate measurement of inductors and capacitors thru the HF region, say 30 MHz max. I tend to be a bit lazy and like alligator clips, clip in the unknown and take a measurement. If you are not too sloppy you can get away with this! But I offer this up as a query... How simple you can put together a test set for measurement of components after doing a careful cal and get reasonable results? ________________________________ From: [email protected] <[email protected]> on behalf of tuckvk3cca <tuckvk3cca@...> Sent: Wednesday, August 7, 2019 10:49 PM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Measurement challenge A good exercise is to use your VNA to measure the very high unloaded Q of Toroid coils. I have good success with J. Oppenheimer's KN5L method for toroids with Q up to 230 using a single turn sense coil throigh the toroid connected to the VNA. Above all the measurement's agreement with theoretical values for Q and phase shifts is a good check of your calibration.Accurate measurement of unloaded high Q is by no means trivial. See the link to his webpage below: from my Samsung Galaxy smartphone. -------- Original message --------From: alan victor <avictor73@...> Date: 07/08/2019 21:45 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] Measurement challenge I am not talking about calibration. THE CALIBRATION BY WHATEVER METHOD YOU DESIRE IS NOW DONE. Complete. Now we desire to measure some components. We are now in a position to use the NanoVNA as a component analyzer. Go measure... Alan |
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Re: Annotated nanoVNA menu diagram
Terrific addition to our knowledge of the NanoVNA.
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Thank you very much, Stuart K6YAZLos Angeles, USA -----Original Message-----
From: Oristo <ormpoa@...> To: nanovna-users <[email protected]> Sent: Wed, Aug 7, 2019 4:52 pm Subject: [nanovna-users] Annotated nanoVNA menu diagram That URL involves neither JavaScript nor cookies. It is my first CSS learning exercise and certainly buggy. For example, branches wrap badly on narrow displays. It displays OK on an iPad, but hovering requires a mouse.. Hovering a mouse pointer over some text boxes should pop up tooltip hints. Underlined TEXT have hyperlinks to longer descriptions in a plain HTML text file on the same website. TRACE and FORMAT entry annotations are yet to do. I will also investigate iPad support.. |
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Annotated nanoVNA menu diagram
That URL involves neither JavaScript nor cookies. It is my first CSS learning exercise and certainly buggy. For example, branches wrap badly on narrow displays. It displays OK on an iPad, but hovering requires a mouse.. Hovering a mouse pointer over some text boxes should pop up tooltip hints. Underlined TEXT have hyperlinks to longer descriptions in a plain HTML text file on the same website. TRACE and FORMAT entry annotations are yet to do. I will also investigate iPad support.. |
CT2FZI
Oristo
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