Re: Increasing measurement range (ohms) ?
Thanks. I had a blue one on order but have a green one on order too, now.
At least they're cheap !
toggle quoted message
Show quoted text
On Tue, Nov 19, 2019 at 12:44 PM Oristo <ormpoa@...> wrote: Hi Adrian -
A green (not blue) ~US$10 reflection bridge
e.g. from eBay
with matched SMA references (want a matched pair to calibrate nanoVNA
CH1)
Why is a green reflection bridge better than a blue one ?
(Presumably it's not just a matter of preferred colour ..)
Blue are bad clones of transverters-store design and are wired wrong.
|
Re: Increasing measurement range (ohms) ?
Hi Adrian - A green (not blue) ~US$10 reflection bridge
e.g. from eBay
with matched SMA references (want a matched pair to calibrate nanoVNA CH1) Why is a green reflection bridge better than a blue one ?
(Presumably it's not just a matter of preferred colour ..)
Blue are bad clones of transverters-store design and are wired wrong.
|
Looking at the datasheet I'm wondering if I am not mixing up two devices. Can't find anything there. Bridge design was a the green ebay resistive 3GHz bridge module driven through the REF and DUT inputs and INPUT was used to observe balance. I only remember I could not get good balance but it was a very quick test and you may be more persistent . -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
|
Re: Increasing measurement range (ohms) ?
On Sat, Nov 16, 2019 at 5:59 PM Oristo <ormpoa@...> wrote:
A green (not blue) ~US$10 reflection bridge
e.g. from eBay
with matched SMA references (want a matched pair to calibrate nanoVNA CH1)
Why is a green reflection bridge better than a blue one ? (Presumably it's not just a matter of preferred colour ..)
|
Gabriel,
Nice analysis. It will be interesting to see what actual changes make it into hugen's upcoming pcb modification where he intends the bring out the UART interface lines for users to experiment with. I know he is seriously considering a change to the FM9688 to lower USB noise. I would like to see component value changes to better match port 1 to 50 ohms.
- Herb
|
Thanks Larry
Jos
Op 18-11-2019 om 20:23 schreef Larry Rothman:
toggle quoted message
Show quoted text
That's the LiIon battery protection circuit - don't touch it.It prevents the battery from being overcharged or discharging too much.Read up on battery protection circuits here:?
On Monday, November 18, 2019, 2:14:56 p.m. GMT-5, Jos Stevens <jrs@...> wrote:
Hi all
Under the battery (3.7V - 450mAh) of my nanovna-H is taped a tiny pcb
with 2 IC's, 2 resistors and a capacitor (all SMD), is there anyone who
knows what this is ?
Jos
Op 18-11-2019 om 10:49 schreef DL8AAP:
Doesn't work on my Linux Mint 18.3 cinnamon with Python 3.6.
Python has to be updated to 3.7. I tried that before, but other apps stopped working then. So I rolled back to 3.6
Carsten
|
Gabriel Did you take into account the fixed time offset between the + and - outputs of the ADF435x? I could not get good bridge balance but this was in a experimental setting -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
|
Re: Increasing measurement range (ohms) ?
Hello,
There is a trick that is used by people that work on particular frequencies for example in power microwaves 2450MHz.(oven-people)
They use a lambda/4 line at that frequency with a typical 50 Ohm VNA to measure high impedances.
Lambda/4 is a transformer: one side is the low -z end the other the side the high-z end.
Of course the lambda/4 is first characterised ( Q, bandwith, etc.).
I really can't remember nor find the reference to it. It's too long ago, sorry.
Jan ON4MMW
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of alan victor Sent: 18 November 2019 23:17 To: [email protected]Subject: Re: [nanovna-users] Increasing measurement range (ohms) ? Hello KV5R, sure. Good questions and good points. I'll try to go through your note step by step question with a response. ================== Rather than constructing, would something like an inexpensive "QRP Antenna Tuner" be a useful accessory for the nano? It's just a stepped inductor and air-variable capacitor, with box and connectors, with a moderate impedance matching range. ================== YES. AGREE. However, the motivation in building your own is to use the VNA in making certain that the self resonate frequency of each of the matching components are WELL above the application or TEST frequency. Otherwise you are dealing with a frequency dependent L or C. Ideally the L or C maintains a C value or an L value that over its entire variable range is spot on the same value, say at 1 MHz or at 30 MHz! Not all L's and C's behave in that manner! Particularly LARGE HV variable caps have a pretty significant parasitic inductance. Hence their C value will shift quite a bit with frequency despite, you never mechanical change their value! Now normally we don't care about this affect, but if were trying to use the matching network as an instrument, then we may need to take care about this subtle aspect. ======================== Understood. But I think a more typical use-case would be measuring at the end of the feed-line (typically low-loss open-wire parallel "ladder line"), as for high-Z non-resonant antennas, the feed-point impedance is rarely meaningful, and the transmission line impedance varies with length and frequency. I suppose one might measure it at the feed-point if the desire is to design a tuning stub or other Z-match device at the feed-point. ========================== YES! I tend to look right at the antenna feed point. Yes, the series lines and stubs will further modify this Z. But that is part of the MATCHING PROBLEM. Our first challenge is to find the accurate Z at the antenna driving point. So that's where the little high performance matchbox tuner comes in. If we adjust this tuner to obtain a super return loss at its 50 ohm port where our VNA is connected, then the TUNER contains the information we seek, namely the antenna impedance! =================================== I'm not understanding how to connect and use the nano to determine the L and C values of this little L-network. I assumed one would need an LC meter for that. ============================================ WELL, you are not. However, you are using the VNA to assist in the construction of this well performing tuner whose readout of C and L values (assume a simple L network) are ACCURATE. So you need to carefully characterize the C and L's used in the tuner construction to eliminate as much parasitic from their design. Remember, we are not designing a tuner to handle any power! We are designing a tuner to have stable impedance characteristics. Hence small array of C's or piston caps and an array of tapped air wound L's would be suitable. Recall, the tuner is being driver by the nanovna which has feeble power! ================================================== Knowing the L and C values required to achieve the good return loss permits you to calculate the antenna Z. ================================================== WHEN the L and C's of the tuner are set to produce a high performance return loss as measured by the vna, then in essence, if the tuner were terminated (where the vna was positioned) with 50 ohms and we were to look into the TUNER where the antenna was connected, we would see the ANTENNA Z CONJUGATE. Wow, that's a mouth full. The best was to see this is to do an example problem and a simulator like LT Spice is a nice tool to learn. Or there are other SMITH GRAPHIC programs that are quite helpful to assist in this process. Standby and I will see what I can assemble. Alan
|
Hi Herb,
at that time, during the further development of EU1KY AA, DH1AKF conducted frequency extension experiments where the bridge circuit levels were modified. Simultaneously, he modified the firmware to create mods by DH1AKF, which was followed by further modifications to KD8CEC. I think it's worth reviewing the changes, even though the measurement circuitry is different. More info can be found on their website, which I have followed, so I have links there too. Can you see here:
Hope I could help something.
73, Gyula HA3HZ
|
Group members who are into hardware experimentation might be interested in trying some of the latest improvements reported by Pmax65 at, " ".
He is reporting improvements in the reflectometric bridge section that result in better operation out to 1500 MHz. It would be nice if more than one person saw similar improvements and reported back their own findings. His attached plots look cleaner than the ones Erik reported during his own experimentation, which I consider the baseline.
- Herb
|
Re: Is the NooElec nanoVNA any good?
On Mon, Nov 18, 2019 at 07:49 PM, Roger Need wrote:
"Sound like NooElec is selling an older version board. Anyone know what is the version number of the PCB? (3.1? latest is 3.3) Is this a NanoVNA-H or a
clone?"
====================================================================
Roger,
According to hugen, "Looking at the images shared by the group users, the version sold by Nooelec should be the version I sold in September. I don't know where they bought the version and sold it, but it was made by me."
This is from message number #6802.
- Herb
|
Re: BH5HNU NanoVNA-F Aliexpress site no longer there?
Dear Conrad, I'm a member of NanoVNA-F development team, because of BH5HNU's personal problem, the hamelec aliexpress store is no longer selling product now, but we'll reopen a new store soon, it maybe takes 2-3 weeks. You can get newest infor from our own groups: /g/nanovna-f When the new store open we'll release claims at that group at the first time.
On Mon, Nov 18, 2019 at 11:52 PM, Conrad, PA5Y wrote:
Hello all, I was going to place an order for the NanoVNA-F today and the link
that I have for the BH5HNU version is down. I would like to buy from a
reputable source and I know that huygen is the developer. So can anybody
advise me where to buy the genuine article?
Regards
Conrad PA5Y
|
Re: Is the NooElec nanoVNA any good?
Sound like NooElec is selling an older version board. Anyone know what is the version number of the PCB? (3.1? latest is 3.3) Is this a NanoVNA-H or a clone?
|
Re: BH5HNU NanoVNA-F Aliexpress site no longer there?
On Mon, 18 Nov 2019 at 17:43, hwalker <herbwalker2476@...> wrote:
Dave,
Yes, Hugen's product is the 2.8" NanoVNA-H, and BH5HNU's is the 4.3"
NanoVNA-F. BH5HNU has been so busy with orders and production that he
hasn't had a chance to devote a lot of time to documentation and software
development. Because the NanoVNA-F and NanoVNA-H have a lot of
crossover, not only in how they operate, but in user's who own both
models, ssome NanoVNA-F owners join the discussions on this board looking
for information.
It leads to confusion at times because the NanoVNA-H's firmware is more
advanced than the NanoVNA-F. The NanoVNA-F owner then begins to wonder why
a feature described in the NanoVNA's operating manual isn't available on
his device.
Herb
Yes, I got the feeling that the -F version was a bit less advanced. I have the standard model, and will eventually upgrade, but I will make a decision about what to upgrade to later. -- 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
|
Re: Increasing measurement range (ohms) ?
Here is a picture story presented as 5 figures which hopefully will clear some questions. In the five figures we start with a circuit representation of a dipole which is a bit unusual as it has a resonant port Z of 500 ohms, pix_1. And it is set to achieve this at 7.1 MHz. If the VNA were connected to such an antenna the super VNA would demonstrate a S11 reflection plot contour vs. frequency on the Smith Chart shown in blue, see pix_2. For now, pay no attention to the plot in RED. We now add our simple L tuner shown in pix_3. And we connect our VNA to the 50 ohm match port and tune to achieve the best return loss possible. See pix_3, the tuner with antenna and pix_4, the return loss. We have achieved a return loss of over 40 dB. If we were to return this tuner network back to calculation what we would find is a conjugate S11 impedance profile that at a single frequency, namely 7.1 MHz that is exactly our antenna Z at this point, portrait of this Z is shown in RED in pix_2. Note it exactly crosses the antenna Z of 500 ohms. If the antenna Z at some other frequency point were complex, the same occurrence would occur. Again, at one specific frequency a real and complex point would occur synonymous with the tuner achieving best return loss at that single frequency. It is worthy to note, that if the tuner were allowed to be more complex, add more elements, that the trajectory of this plot shown in RED would match with higher fidelity over a broader range of frequencies. I hope this clarifies some of the points.
Alan
|
Re: BH5HNU NanoVNA-F Aliexpress site no longer there?
Thanks for the clarification!
For some reason the Version 2 devs think that they can only offer
a $50. price-point device with a small display.
For some reason they don't see that offering a "B" (or some other
nomenclature) version - at a higher price - makes good business
sense.
Indeed - someone could offer one without a display at all - and
just provide a micro-HDMI connector (like the Raspberry Pi4).
IMHO, YMMV ... David KD4E
toggle quoted message
Show quoted text
Isn't there a 3rd path - the "2"? "H" has the best firmware but older
hardware & small display, "B" larger display & some hardware updates, but
older firmware, "2" about to release newer hardware & firmware but small
display. Sure wish they'd combine efforts.
===============================================================
David,
Currently we have the following products being sold:
1. 2.8" NanoVNA (Hugen's MOD of edy555's original open source project). All 2.8" devices marketed as" NanoVNA" are also clones of the open source project.
2. 2.8" NanoVNA-H (Hugen added the "-H" suffix to his product to distinguish it from other clones being sold.) His NanoVNA-H product also has a plastic case, has the diode mounted for battery voltage monitoring, has proper USB-C terminators and the firmware has been upgraded to at least ver 0.2.3.2. Cost is still around the US $50.00 range.
3. 4.3" NanoVNA-F (BH5HNU's NanoVNA with a larger screen, different operating system and different firmware.)
Version 2 NanoVNA's probably won't appear on the scene until into the New Year. There is not a lot of incentive for cooperation. Each product designer has a small window to re-coop his or her efforts before the cloner's reverse engineer their pcb designs and cut their profits.
- Herb
|
Re: errors of "error" models
|
On Mon, Nov 18, 2019 at 02:01 PM, Larry Rothman wrote:
ip5303
Thanks Larry. I had looked at a lot of posts regarding "battery" but had not seen a report of similar behavior. I will take your advice.
|
Re: BH5HNU NanoVNA-F Aliexpress site no longer there?
Hello Erwin, I am quite happy at number 2 ? Good to see you here.
73
Conrad PA5Y
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of DK5EW, wini via Groups.Io Sent: 18 November 2019 17:58 To: [email protected]Subject: Re: [nanovna-users] BH5HNU NanoVNA-F Aliexpress site no longer there? Hi Conrad, nice to meet you here so I guess I'm the 1. and you are the 2. 144MHz EME guy in the group :-) I was lucky to buy 3 pieces of the -F version before he closed the shop but you may have read that his new shop is open soon. Take care Conrad and always good deep decode. 73's Erwin/DK5EW
|
Re: BH5HNU NanoVNA-F Aliexpress site no longer there?
My mistake David.
Conrad
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Dr. David Kirkby, Kirkby Microwave Ltd via Groups.Io Sent: 18 November 2019 17:22 To: [email protected]Subject: Re: [nanovna-users] BH5HNU NanoVNA-F Aliexpress site no longer there? On Mon, 18 Nov 2019 at 15:52, Conrad, PA5Y <g0ruz@...> wrote: Hello all, I was going to place an order for the NanoVNA-F today and
the link that I have for the BH5HNU version is down. I would like to
buy from a reputable source and I know that huygen is the developer.
So can anybody advise me where to buy the genuine article?
Regards
Conrad PA5Y Is BH5HNU Hugen? I thought Hugen was working on nanoVNA-H, and BH5HNU on nanoVNA-F. Dave. -- 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
|
Oristo
Gyula Molnar
Roger Need
Dr. David Kirkby, Kirkby Microwave Ltd
gin&pez@arg