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Re: nano VNA-H will not connect via USB to control apps on Win10 - help please
SteveH
Hi Brian,
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Have you tried a different USB cable?? I use the same cable that I use with my Android cell phone and it works perfectly.? I use Win 10 and I never had to install different drivers... NanoVNA connected right out of the box.? I'm not saying that this will absolutely solve your problem, but sometimes we jump to the conclusion that the problem is much more complicated and difficult than it actually is...? ; ) Good Luck! Steve N0GWC On 8/29/23 8:32 PM, Brian Stokes wrote:
I posted this query on Jul 17 #33483 |
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Re: nano VNA-H will not connect via USB to control apps on Win10 - help please
I don't think you need to add any drivers on Win 10... (Pretty sure, I didn't, anyway. But it's been quite a while.)
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You might try going into Device Manager, select View / Show Hidden Devices, and remove the hidden COM devices (they'll be shown in gray.) Disconnect your nanoVNA first... You could even watch devices and you plugin your nanoVNA, and see what's actually going on. (It actually starts as a USB device, and the driver makes it into a COM device.) Paul On 8/29/23 18:32, Brian Stokes wrote:
I posted this query on Jul 17 #33483 |
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nano VNA-H will not connect via USB to control apps on Win10 - help please
Brian Stokes
I posted this query on Jul 17 #33483
There were no helpful replies. I have tried installing every USB driver I can find for the nanoVNA but none of them makes the nanoVNA appear in the list of USB devices. Have installed Cypress driver and 64 bit ST virtual COM port app. No new COM ports appear when VNA is connected nor when virtual COM port app installed. Device manager shows new 'Unknown USB device (device descriptor request failed)' when VNA-H is connected and powered up. Cable appears to be good since Device manager sees the VNA. Tried several apps, VNA-QT, nanoVNA sharp 1.03, nanoVNAsaver, none will connect. PC is Win 10. Thanks for your help. |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
For large, high-Q coils, some crystal set builders use a styrofoam cake dummy like this:
Styrofoam is as close to air as anything solid I know of. It may be tedious to set up, but if you can support whatever you're measuring with fishing line you should be able to eliminate all support interaction. But you still have to worry about other stuff in the room. One time I was trying to accurately measure the Q of a large coil with my HP 4342A Q meter. I was astounded to find that I had to remove myself several feet and crouch down to eliminate interaction with my body. Even then I wasn't sure I got rid of it all. I couldn't read the meter from any farther away. Brian |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
On 8/29/23 1:55 PM, W0LEV wrote:
Large styrofoam blocks are the "standard" in professional communities. AtWe use blocks covered with static dissipative film (Amstat, etc.) The surface resistance is sufficiently high that it doesn't load the RF system, but it also prevents the charge that inevitably accumulates on foam from destroying your electronics. |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
Large styrofoam blocks are the "standard" in professional communities. At
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home, with all the RF test equipment, I use either corrugated boxes or an empty 50-gallon rubbish can. I could buy large styrofoam blocks from Hobby Lobby (at least they used to carry them), but I'd have trouble storing them with wifie. Dave - W?LEV On Tue, Aug 29, 2023 at 7:56?PM Brian Beezley <k6sti@...> wrote:
Corrugation should lower the dielectric constant and loss of any material-- *Dave - W?LEV* --
Dave - W?LEV |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
Corrugation should lower the dielectric constant and loss of any material roughly in proportion to its air content. So corrugated cardboard should have better specs than the uncorrugated cardboard specs I quoted. However, the electric field of the object under test will be maximum where it touches the support. It's there where the dielectric properties of the support matter. Increasing the size of a supporting box is unlikely to reduce the effect of lossy box material.
Using lossy materials with high dielectric constant is fine for casual measurements. But it pays to use something more transparent to electric fields when the measurement is important. This also applies to the magnetic field. Avoid anything ferromagnetic or conductive nearby. Brian |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
One can easily MEASURE the ¦År of the corrugated box material. Build a
parallel plate capacitor using aluminum foil, single or double-sided FR-4 PCB, or some other creative set of flat conductors. Measure the capacitance using the NANOVNA (Smith Chart) with only air between the plates. Then slip in and fill the volume between the plates with your unknown material. Again measure the capacitance. Since the capacitance is a linear function of ¦År, the ¦År of the unknown material is the ratio of the two measurements, unknown over air measurements of the two capacitances. What's more, you can measure the ¦År as a function of frequency as well. Dave - W?LEV On Tue, Aug 29, 2023 at 7:23?PM W0LEV via groups.io <davearea51a= [email protected]> wrote: Possibly the ¦År rating of the corrugated paper, itself, is well above-- *Dave - W?LEV* -- Dave - W?LEV |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
Possibly the ¦År rating of the corrugated paper, itself, is well above
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unity, which I seriously doubt. But a large box is pretty much all air with an ¦År miniscually larger than unity. Dave - W?LEV On Tue, Aug 29, 2023 at 7:03?PM Brian Beezley <k6sti@...> wrote:
On Tue, Aug 29, 2023 at 11:41 AM, W0LEV wrote:--I used to use cardboard to support things until I found these 1 MHz specs *Dave - W?LEV* --
Dave - W?LEV |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
On Tue, Aug 29, 2023 at 11:41 AM, W0LEV wrote:
I used to use cardboard to support things until I found these 1 MHz specs for cardboard with a density 0.5 ounces per cubic inch: dielectric constant 6, loss tangent 0.04. By contrast, styrofoam type 103.7 has a dielectric constant of 1.03 and a loss tangent of 0.000021. At 3 GHz the loss tangent is 0.0001. Brian |
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Re: US Manufacturers?
When I worked on GPS initial design we had a rigorous spec for the noise
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temperature of several of the receivers. This was in the late 1970's. We could not make the spec with anything from the US at the time but could using an NEC part from Japan. At the time this was a national security issue with the fear of "hijacked' devices from the Soviet Union or elsewhere with unwanted "codes" embedded in them. This was WELL before the present-day fakes so common from China. We ultimately had to get a letter from the Pentagon, yes, the Pentagon (!!), to use the NEC part. I saw the letter. Be glad this issue is just political and not linked to national security. Dave - W?LEV On Tue, Aug 29, 2023 at 6:38?PM Jim Lux <jimlux@...> wrote:
On 8/28/23 11:23 AM, drfuka@... wrote:--Howdy,project that is regulated by The Build America Buy America Act and NDAA889 *Dave - W?LEV* --
Dave - W?LEV |
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Re: US Manufacturers?
I was just speaking with a fellow who does such work and, unsurprisingly, his first question to me was "How many initially and per year and what is the budget?".
It might wind up cheaper renting a Keysight/Anritsu/Copper Mountain commercial unit once all of the qualified vendor paperwork (which is also not free) gets settled. Of course none of them are made in USA either. 73, Don N2VGU |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
Dry discarded corrogated shipping boxes also work well.
Dave - W?LEV On Tue, Aug 29, 2023 at 12:25?PM Donald S Brant Jr <dsbrantjr@...> wrote: On Tue, Aug 29, 2023 at 04:12 AM, Bob Ecclestone VK2ZRE wrote:--I have found that blocks of Styrofoam are excellent for this use; *Dave - W?LEV* -- Dave - W?LEV |
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Re: US Manufacturers?
On 8/28/23 11:23 AM, drfuka@... wrote:
Howdy, The Buy American Act probably falls in the exception: "the items to be procured or the materials from which they are manufactured must be present in the United States in sufficient and reasonably available commercial quantities of a satisfactory quality. The provisions of the act may be waived if the head of the procuring agency determines the act to be inconsistent with the public interest or the cost of acquiring the domestic product is unreasonable. " The items to be procured aren't present in the US. In my government funded job, we buy things from foreign mfrs all the time: Think Rhode+Schwarz test equipment, SpaceWire test equipment, or even more mundane, fancy RF cables. Yes, you have to fill out a form saying why you can't get it from a domestic supplier. NDAA889 is potentially more troubling, but I think it covers only "Telecommunications Equipment and Services" and the NanoVNA doesn't fall into that bucket. |
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Re: Not available at Ali Express / Zeenko
Order from R&L Electronics:
* No connection other than ordered quite a number of Chinese electronics including the NANOVNAs and TinySAs / Ultra. My credit card issued on my CU will not deal with AliExpress. . . . nor will I. Dave - W?LEV On Tue, Aug 29, 2023 at 5:55?PM Manfred Mornhinweg <manfred@...> wrote: I placed a lot of orders on AliExpress over several years, including the-- *Dave - W?LEV* -- Dave - W?LEV |
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Re: Not available at Ali Express / Zeenko
I placed a lot of orders on AliExpress over several years, including the NanoVNA, TinySA, etc. Most of the time it worked fine. Until recently! AliExpress sent my last three orders through a little bad logistics company called BlueExpress, that doesn't serve my area, and these orders never arrived. The tracking says "delivery attempt failed", and in e-mail communication with that logistics company they told me that they are holding the parcels, and want me to travel to a distant city to pick them up!
I complained to AliExpress, requesting refunds, and they refused, falsely claiming that the parcels are waiting in my local post office. Of course they are NOT there, and after asking BlueExpress by e-mail, they told me that they do not deliver to post offices. I forwarded that e-mail to AliExpress, and then they judged that it was all my fault, and closed the case with no refund, and no further appeal possible. I lost my money and my time. So AliExpress is no longer an option for me. It would be good for sellers in China to offer their goods on more places. Too many just concentrate on AliExpress. But AliExpress is giving trouble to too many people lately. We need sales sites that give the buyer and seller options for shipping, that allow choosing the actual company that will do the shipping. For me the postal service works fine, but AliExpress doesn't offer that anymore. Just "Standard" or "Economy" shipping, and AliExpress chooses which shipping company to use - and for my last three orders they chose one that can't deliver to me! Sorry to let my steam off here in the forum - but I think the matter is of interest to possible future buyers of NanoVNAs, and certainly to the maker! |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
On Tue, Aug 29, 2023 at 04:12 AM, Bob Ecclestone VK2ZRE wrote:
I have found that blocks of Styrofoam are excellent for this use; polystyrene is a pretty good dielectric and the foam is 99% air so even better. 73, Don N2VGU |
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Re: NanoVNA for 120 ohm Twin wire Balanced lines
Hi Arun,
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I can vouch for Mini Circuits transformers. I had Mini Circuits build some custom 100 Ohm balanced hybrid splitters for a VDSL broadband startup project in Australia. We used 100 Ohm Cat5 cable for the "last mile" and these were used to split one physical VDSL port into two isolated VPN ports. The splitters consisted of one of their standard 50 Ohm unbalanced hybrid splitters with 50-100 Ohm balancing transformers on each of the three ports, all in a 16 pin DIL package. Excellent performance over 1MHz-30MHz, better than 26dB between output ports if I recall. It is your choice, but the general consensus on these forums seems to be to use a centre tapped balanced secondary. You can then chose to connect the centre tap to the 50 Ohm unbalanced port ground or not. You will need to make up an appropriate cable termination jig and to make up your own O-S-L-T terminations for calibration at your chosen test impedance. Be aware that how you support the cable will affect the measurements. Just be consistent about how you support and orient the cable if you intend to compare various results. If you intend to use one of the NanoVNA computer apps, then a ferrite decoupled USB cable is also highly recommended to minimise counterpoise effects. Regards...Bob VK2ZRE On 29/08/2023 5:01 am, Arun wrote:
Has anyone used a NanoVNA to characterize a Twin wire twisted Balanced line like say a CAN bus line or an ISO-SPI balanced 120 ohm line? |
Paul - AI7JR
Donald S Brant Jr
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