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I just got one for $50 out of curiosity. To put it bluntly, I'm pretty baffled. Not sure if it is because of bugs or the user. But I often get nonsensical values displayed. At the moment it is set to sweep from 10-20 MHz. But with both ports unterminated I get an SWR of 1.18 which seems absurdly low. However it does go to 1.0 if I put a 50 ohm load on it.
I've downloaded the FW update stuff and manuals via the group file folder link.
How does one tell if it is actually sweeping? Is there UI feedback?
Mine is not shielded. Is there any documentation on adding shielding?
How does one access the console port? Is that a USB tty on Linux? If so, what are the port settings.
Also where does one find the source code?
Thanks,
Reg
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Did you do the full calibration? It sounds like something there didn¡¯t fully ¡°take.¡±
If you select a SWR plot you should see a graph and the left will be 10 and the right 20 mhz.
You don¡¯t really need the shielding.
Peter
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On Aug 30, 2019, at 8:09 PM, Reginald Beardsley via Groups.Io <pulaskite@...> wrote:
I just got one for $50 out of curiosity. To put it bluntly, I'm pretty baffled. Not sure if it is because of bugs or the user. But I often get nonsensical values displayed. At the moment it is set to sweep from 10-20 MHz. But with both ports unterminated I get an SWR of 1.18 which seems absurdly low. However it does go to 1.0 if I put a 50 ohm load on it.
I've downloaded the FW update stuff and manuals via the group file folder link.
How does one tell if it is actually sweeping? Is there UI feedback?
Mine is not shielded. Is there any documentation on adding shielding?
How does one access the console port? Is that a USB tty on Linux? If so, what are the port settings.
Also where does one find the source code?
Thanks,
Reg
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Welcome to the forum, Reg.
All your answers are in the wiki and files sections of the forum.
You're seeing weird reasons because you should run a calibration before using the device. It's documented in the files section. There is also a long thread on calibration as well.
Have a look at some of the photos that have been uploaded, showing how shields have been added.
There are 2 versions basically: ch and aa
Ch is the 4 trace f/w and aa is the 2 trace antenna analyser f/w
Again, most of what you're looking for is here.
Enjoy your new toy!
Larry
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Don't forget to SAVE to 0 after you calibrate the unit.
When the unit is turned on, it recalls memory 0 calibration.
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Larry,
Thanks. I did a recalibration and it now is producing sensible answers. I'm still a bit confused by the UI, but that may be old FW or PEBKAC.
I did not see anything about shields when I looked through the files section, but I'll look again.
I'm quite excited by this as it is the RF version of the $20 LCR meter and the $10 DMM. I have an 8753B/84046A, VNWA and xaVNA so I didn't need this. But I remember all too well being a poor student trying to build a 40 M DC receiver and failing for lack of T&M gear. I had a VOM, DMM and 5 MHz recurrent sweep Heathkit IO-18 scope. Not exactly a recipe for success building RF band pass filters :-(
It will be very interesting to see what I find when I submit it to the tender mercies of my test bench ;-)
At this point my biggest concern is the limited flash of the MCU. I can think of a lot of features to add. But that may be better done in a PC program.
David Kirkby talked me into buying this. I'm really glad he did. I spent some time working on designing one, but abandoned the project when I realized there were a lot of other people doing the same thing. Edy555 has done a fantastic job.
#$%^&*!!! I was just tightening the short on CH0 with a Suhner torque wrench when both the ground pins on the SMA PCB connector broke off!!! Fortunately I have a bunch of replacements, but it does not give me much confidence in their quality :-(
sigh.....
Reg
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Hi Reg, DO NOT USE A TORQUE WRENCH.
Oh well... lesson learned.
DO GET SOME CONNECTOR SAVERS.
That is SMA female to male adapter. If you continue to attach DUTs to the
SMA connector directly on the VNA it will deteriorate
Alan
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@reg
let that be a lesson to you. the fancy Suhner torque wrench is for a fully panel mounted SMA connector. esp. the kind with a screw fastener at all four corners.
here on the nanovna, you have a SMA connector mount on a PCB edge held in place mostly by the strength of the solder.
you're not assembling flight hardware. just use your fingers instead, okay?
- 30 -
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I've been doing a *lot* of TDR testing of RF connectors using a Tek 11801 sampling scope with an SD-24 TDR head. Torquing the SMA connectors to spec is *very* important to getting repeatable results. I have been watching the reflection at the connectors disappear as the wrench goes "click".
I think part of the problem with the nanoVNA is the ground pins were only soldered on one side. I'll use bulkhead connectors when I put it in a metal case hammer formed from 0.018" galvanized steel sheet. I have a bunch of scraps from a local HVAC shop. I just need a block of wood the right size.
Have Fun!
Reg
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On Saturday, August 31, 2019, 3:54:45 AM CDT, alan victor <avictor73@...> wrote:
Hi Reg, DO NOT USE A TORQUE WRENCH.
Oh well... lesson learned.
DO GET SOME CONNECTOR SAVERS.
That is SMA female to male adapter. If you continue to attach DUTs to the
SMA connector directly on the VNA it will deteriorate
Alan
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¡°Torquing¡± SMA connectors gives a repeatable penetration of the center pin into the female. That is important and more and more important as you move higher in frequency. The value of torque used is not particularly important so long as it is consistent from calibration to measurement to permanent installation. I believe there are recommended settings for SMAs.
I can understand torquing for TDR measurements at microwave frequencies. But using it for Return Loss measurements at 450 MHz is probably overkill with emphasis on ¡°kill¡± in this case. It is not necessary¡.. finger tight is fine and will save wear and tear on the connectors. 99.9% of casual SMA users get by just fine with finger tight connections.
Anyone intending to use this wonderful device to make repeatable measurements plus or minus 0.01 dB at 900 MHz is probably just kidding themselves and torqued or not, will likely be disappointed in the results. But it was $50! Not $50,000!
I have said it before¡. there is a wide, wide range of technical expertise and capability represented on this board. Those with a high level of knowledge on the art of VNAs will contribute best by gauging their input, comments, and recommendations to the hobby user and not to the user interested in doing TDR calibrations of an SMA connector at 4 GHz.
End of rant¡¡ thanks for reading.
WA8TOD
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On Aug 31, 2019, at 8:11 AM, Reginald Beardsley via Groups.Io <pulaskite@...> wrote: I've been doing a *lot* of TDR testing of RF connectors using a Tek 11801 sampling scope with an SD-24 TDR head. Torquing the SMA connectors to spec is *very* important to getting repeatable results. I have been watching the reflection at the connectors disappear as the wrench goes "click". I think part of the problem with the nanoVNA is the ground pins were only soldered on one side. I'll use bulkhead connectors when I put it in a metal case hammer formed from 0.018" galvanized steel sheet. I have a bunch of scraps from a local HVAC shop. I just need a block of wood the right size. Have Fun! Reg On Saturday, August 31, 2019, 3:54:45 AM CDT, alan victor <avictor73@...> wrote: Hi Reg, DO NOT USE A TORQUE WRENCH. Oh well... lesson learned. DO GET SOME CONNECTOR SAVERS. That is SMA female to male adapter. If you continue to attach DUTs to the SMA connector directly on the VNA it will deteriorate Alan
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Hello Torque lovers...
Here is a compromise solution and works "well" .
I don't want to torque anyone off but try SMA spinner nuts.
It will also prevent or at least assist keeping the center pin
from rotating and depositing gold shavings onto the dielectric.
Frank S who makes the Nanovna cases also has these available.
Alan
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I'd use the cables that came with the unit and only finger tighten them.
You might want to flow some more solder to the ground attachments on the SMA connectors, it's possible that they were not soldered very well when the unit was made. Since I don't see myself needing to use the VNA at frequencies higher than the 2 meter band, I'm not too worried about miss-matches with the connectors, and I don't see the need to tighten them any better than I can do with my bare hands.
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On 8/31/19 4:54 AM, alan victor wrote: Hi Reg, DO NOT USE A TORQUE WRENCH.
Oh well... lesson learned.
DO GET SOME CONNECTOR SAVERS.
That is SMA female to male adapter. If you continue to attach DUTs to the
SMA connector directly on the VNA it will deteriorate
Alan
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Here is what Alan is talking about:
The "kit" includes all in the picture (except my cable) for $12.50 plus shipping (so far $3.09 to CA)
Case, 4 screws, anti glare screen protector 2 SMA "knobs" 3 small cal kit knobs
If interested, contact me at
frank@...
Thanks
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On 8/31/2019 9:24 AM, alan victor wrote: Hello Torque lovers...
Here is a compromise solution and works "well" .
I don't want to torque anyone off but try SMA spinner nuts.
It will also prevent or at least assist keeping the center pin
from rotating and depositing gold shavings onto the dielectric.
Frank S who makes the Nanovna cases also has these available.
Alan
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The prongs on one side of the board were not soldered at all. I've (I hope) almost finished fabricating a case from 0.018" galvanized steel and will replace the factory SMA connectors with bulkhead mount units. Of course, I've had to make the same part 3-4 times, so I may get to make them again, but I'm hoping I can make the LCD cutout and punch the screw and SMA holes without starting over yet again.
FWIW You can get all the small scraps of 0.018" galvanized steel you want from any HVAC shop just by asking. It solders well and provides both E & H field shielding. If you standardize on an enclosure you can build a brake which will bend a close fitting U box very quickly. If you have unbent blanks cut to size they take up no space until you bend them.
I'm using a Harbor Freight 3 in 1 sheet metal machine and getting beat up for lack of a proper back gauge and experience.
I tried hammer forming, but was not happy with the result. Getting the metal to shrink at the corners takes some practice. But it is a *lot* stiffer. I need to try using a hydraulic press and hardwood dies or rubber forming.
Have Fun!
Reg
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Reg,
I uploaded photos and a template for a housing and N to SMA bulkhead adapter a week ago. I'm just waiting for my adapters to come in. Do a search on the word bulkhead and you'll find my posts.
It's a simple housing and I've already bent my prototype out of thin aluminum.
I made a suggestion that member Hex &Flex add a section to the end of his housing design to hold the adapters. That would make for an ideal device.
Regards
Larry
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I bent up a housing out of 28 gauge galvanized steel (HVAC duct scrap). I tried hammer forming, but was not happy with how that turned out. I might take a crack at hammer forming aluminum, but I didn't want to heat galvanized with a torch and give myself zinc poisoning. So I went with a simple two piece U design.
I got the back cover which holds the connectors 1/16" too long, so I'm going to do it over for the 4th or 5th time. The Harbor Freight 3 in 1 metal machine doesn't have a decent backgauge so it is *very* difficult to set the shear accurately. And to make matters worse, I'm a complete novice at sheet metal. But there's only one way to learn. Keep doing it until you get it right.
I thought about putting N connectors on, but decided to stick with the SMA. I've got an 8753B/85046A. I'm not expecting this to get a lot of use. I bought it more out of curiosity than anything else. If I did use it for serious work, I'd run SMA cables to a fixture.
It's not got enough memory to add much software functionality and I wasn't able to find a pin compatible part with more memory.
Have Fun!
Reg
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This is a housing I was considering. Will need some machining. Was thinking of putting a larger screen and full size connectors on it.
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On Aug 31, 2019, at 6:28 PM, Reginald Beardsley via Groups.Io <pulaskite@...> wrote:
I bent up a housing out of 28 gauge galvanized steel (HVAC duct scrap). I tried hammer forming, but was not happy with how that turned out. I might take a crack at hammer forming aluminum, but I didn't want to heat galvanized with a torch and give myself zinc poisoning. So I went with a simple two piece U design.
I got the back cover which holds the connectors 1/16" too long, so I'm going to do it over for the 4th or 5th time. The Harbor Freight 3 in 1 metal machine doesn't have a decent backgauge so it is *very* difficult to set the shear accurately. And to make matters worse, I'm a complete novice at sheet metal. But there's only one way to learn. Keep doing it until you get it right.
I thought about putting N connectors on, but decided to stick with the SMA. I've got an 8753B/85046A. I'm not expecting this to get a lot of use. I bought it more out of curiosity than anything else. If I did use it for serious work, I'd run SMA cables to a fixture.
It's not got enough memory to add much software functionality and I wasn't able to find a pin compatible part with more memory.
Have Fun!
Reg
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That's a *lot* cheaper and *much* nicer than the one I'm making. I still need to make the holes. The ones for the switches are pretty scary.
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On Saturday, August 31, 2019, 6:41:53 PM CDT, Vince Rooney <vince@...> wrote:
This is a housing I was considering. Will need some machining. Was thinking of putting a larger screen and full size connectors on it.
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I was thinking bigger all around. Better switches. Just use the board.
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On Aug 31, 2019, at 9:40 PM, Reginald Beardsley via Groups.Io <pulaskite@...> wrote:
That's a *lot* cheaper and *much* nicer than the one I'm making. I still need to make the holes. The ones for the switches are pretty scary.
On Saturday, August 31, 2019, 6:41:53 PM CDT, Vince Rooney <vince@...> wrote:
This is a housing I was considering. Will need some machining. Was thinking of putting a larger screen and full size connectors on it.
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Dr. David Kirkby from Kirkby Microwave Ltd
On Sun, 1 Sep 2019 at 00:41, Vince Rooney <vince@...> wrote: This is a housing I was considering. Will need some machining. Was
thinking of putting a larger screen and full size connectors on it.
I think N people will probably do this N different ways. But certainly I agree about the use of larger connectors and decent quality switches. B However, unlike yourself I intended making the enclosure, which will allow me to have a thin top section for the screen. I think perhaps a die cast box might have a lid a but thicker than desirable. However, I would be interested in how you get on. Although it will be quite heavy, some L-shaped aluminium angle is available 1/4¡± thick. I would use that as the bottom and front where a couple of N connectors would be mounted. The sides of the 1/4¡± aluminium could be drilled and tapped to allow the sides panels to be mounted - probably 1.5 mm thick aluminium. That will allow me to have a thin top section where the screen is, but more substantial sections everywhere else. I don¡¯t know if you have seen the Keysight FieldFox range, but they have the ability to add a strap, which I think would be unnecessary on the NanoVNA, but the mounts for the strap form another use. They mean if the unit was dropped, the connectors would not get damaged. Dave.
<>
On Aug 31, 2019, at 6:28 PM, Reginald Beardsley via Groups.Io <pulaskite= [email protected]> wrote:
I bent up a housing out of 28 gauge galvanized steel (HVAC duct scrap).
I tried hammer forming, but was not happy with how that turned out. I might
take a crack at hammer forming aluminum, but I didn't want to heat
galvanized with a torch and give myself zinc poisoning. So I went with a
simple two piece U design.
I got the back cover which holds the connectors 1/16" too long, so I'm
going to do it over for the 4th or 5th time. The Harbor Freight 3 in 1
metal machine doesn't have a decent backgauge so it is *very* difficult to
set the shear accurately. And to make matters worse, I'm a complete novice
at sheet metal. But there's only one way to learn. Keep doing it until you
get it right.
I thought about putting N connectors on, but decided to stick with the
SMA. I've got an 8753B/85046A. I'm not expecting this to get a lot of use.
I bought it more out of curiosity than anything else. If I did use it for
serious work, I'd run SMA cables to a fixture.
It's not got enough memory to add much software functionality and I
wasn't able to find a pin compatible part with more memory.
Have Fun!
Reg
--
Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@... Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales. Company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
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to Frank S,
I am interested in ur "kit" but cannot find ur contact info, sri as I am still noobie lol
pls contact me @ n8aum-at-yahoo-com
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kb3cs
Warren Allgyer
