well looking at the link to owen duffys solution it looks like the ground is common to both connectors then?,cheers all 73
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i think you missunderstand me,on nano the pcb it looks like the body of the sma connectors ie the ground are not electricaly conected to each other,thats what im' trying to find out.ie is is important to keep them seperate electricaly.?
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Re: Jog wheel switch causes problems
#parts
On Mon, Feb 17, 2020 at 03:41 PM, Oristo wrote:
My understanding was the the jog switch affects whatever was most recently selected in menus.
For example, if marker 2 is selected, then jog switch would move marker 2. Then, if stimulus->start is selected, jog switch would affect start frequency....
=========================================================
Oristo,
Thai's my understanding also, but I don't have edy555's firmware version installed so I didn't want to guess. edy555's release notes never mentioned how to change between different jog switch behaviors. My preference would have been to use the jog switch to cycle selection, but he was probably constrained by the fact that depressing the jog switch brings up the on-screen menu and couldn't use that action to cycle selection.
- Herb
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Re: Jog wheel switch causes problems
#parts
Changing the frequency using the jog switch is a feature using certain
firmware, but is disconcerting if you are used to the jog switch changing
marker movement. My understanding was the the jog switch affects whatever was most recently selected in menus. For example, if marker 2 is selected, then jog switch would move marker 2. Then, if stimulus->start is selected, jog switch would affect start frequency....
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Re: HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
Here is another similar set of data:
I think it supports Dave's general conclusion for resistors like 470 Ohms. This was done with a HP8714B VNA that is functionally very similar to the 8753.
However, it also shows more data points. This gives a look that again shows that the fine little nanoVNA is quite fine up to 300 MHz, good but noisy up to 900 MHz and (not shown here) challenging up to 1500 MHz. Nothing really new, but worth keeping in mind.
The spike at 225 MHz for the nano-VNA is repeatable and is an error. Others have seen this.
I did a quick look at a 5100 Ohm resistor, and neither the 8714 nor the nanoVNA was doing well with this. The 8714 was better in the 5 to 100 MHz range.
I have a N2PK VNA that makes very high quality measurements up to 60 MHz. It has an RF I-V adaptor
and
If you want to measure high or low impedance values, this box adds to the accuracy. But, to use this with the nanoVNA would require firmware changes and also the connection to a digital control line, that might be challenging.
73, Bob W7PUA
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Shields must be connected as should the center conductors of any cable
extenders. Highly flexible cables are a good method to embody a connector
saver. Be fure to use good quality cables and connectors. With the cables
connected, the measurement plane (where the cal standards are placed and
measurements are made) becomes the end of the cables.
Dave - W?LEV
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On Mon, Feb 17, 2020 at 10:20 PM <nanovnauser@...> wrote: Hi all,just a quick question,i notice the sma connectors on my vna are
fragile where they join the pcb,i have some beter ones,i thought of
fabricating a piece of copper sheet and mounting them on that,then connect
them to the pcb usung coax pigtails,can the sma conector bodies be
connected electricaly together ,ie the grounds,or insulated from each
other?,cheers.73.
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
|
You may want to look at the elegant solution that Owen Duffy built at:
Dale W4OP
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of nanovnauser@... Sent: Monday, February 17, 2020 5:21 PM To: [email protected]Subject: [nanovna-users] connectors grounding Hi all,just a quick question,i notice the sma connectors on my vna are fragile where they join the pcb,i have some beter ones,i thought of fabricating a piece of copper sheet and mounting them on that,then connect them to the pcb usung coax pigtails,can the sma conector bodies be connected electricaly together ,ie the grounds,or insulated from each other?,cheers.73.
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Note, with clearer screen captures:
50-ohm cal: S11 reads 304.88 ohms real as a folded dipole shoud (on the
right of the chart right where it sould be for 300-
ohms real)
300-ohm cal: S11 reads 53.5 ohms (in the center of the chart since you
have reset the cal position with a 300 ohm cal)
Also note that 53.5 ohms X 6 = 321-ohms, very close
to what you measured with the 50-ohm cal.
This is how a normalized chart works when calibrated to something other
than 50-ohms. You could just as well have taken the chart center as 1, or
unity. With a 50-ohm cal, the center becomes 50-ohms. With a 300-ohm cal,
the center becomes 300-ohms. The values in a normalized chart must be
multiplied by the system impedance of the cal. This is a good method to
make more meaningful measurements when dealing with extremely low and
extremely high impedances. However, the ultimate limitation will always be
the bridge or the directional coupler within the measurement instrument.
The HP 8753 uses a very carefully designed and meticulously machined
directional coupler to accomplish its published specifications (the HP
85047 S-Parameter Test Set mated with the 8753). I am continuously amazed
at how well the little NANOVNA (and all its variants - minus some clones)
compare to this very expensive piece of HP test gear! Credit to the
engineers who made it happen!!!!!!
As far as the additional dips in SWR, the antenna must be in free space to
show only resonances (the horizontal axis on the Smith Chart). Resonance
is defined as +jX = -jX, leaving nothing but real resistance which, for an
antenna, is the sum of ohmic losses in the conductors which make up the
antenna and the radiation resistance which is a 'magic' result of all
things electromagnetic ?? (you don't really want to know- *lots* of
calculus). The higher in frequency you go, the smaller geometries become,
and the easier it is to test in something resembling 'free space'. At FM
broadcast frequencies, its rather difficult without a semi-anechoic chamber
in which to test (read, lots of $$$$$$).
Dave - W?LEV
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On Mon, Feb 17, 2020 at 8:04 PM goscickiw <goscickiw@...> wrote: Thanks, so the only thing I should do is to multiply the
impedance/resistance/reactance values by 6 and they should be correct?
Also looks like the attached picture became very low resolution after
uploading. Here are the full screenshots, with marker details:
Cal. 50 ohm:
Cal. 300 ohm:
The antenna should be tuned to around the center of the CCIR FM band, so
the 95 MHz match is most likely correct.
I'm not sure what causes the other SWR dips, it's just a regular folded
dipole with nothing attached to it. The NanoVNA is right next to it,
connected by a piece of PCB with two holes and an SMA connector soldered
onto it, like this:
Are these dips present just because it isn't an ideal simulation-like
environment?
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
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Re: Android app cable not working!
I use a generic unbranded one that came with a chinese tablet and it works fine with my Galaxy S7. --------------------------- Same with me. I used the charging cable that came with my Xiaomi Mi9, with the USB C connector connected to the NanoVNA, and the USB A connector connected to this adapter bought on Amazon (sorry, I do not have anymore the URL...). Worked at the first try. Android version is 9. Alberto -- /*73 Alberto I2PHD* <<< >>>/
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Hi all,just a quick question,i notice the sma connectors on my vna are fragile where they join the pcb,i have some beter ones,i thought of fabricating a piece of copper sheet and mounting them on that,then connect them to the pcb usung coax pigtails,can the sma conector bodies be connected electricaly together ,ie the grounds,or insulated from each other?,cheers.73.
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Re: Simultaneous S11 and S21 measurements ?
Yes ________________________________ From: [email protected] < [email protected]> on behalf of Neal Pollack <nealix@...> Sent: Monday, February 17, 2020 4:20 PM To: [email protected] < [email protected]> Subject: [nanovna-users] Simultaneous S11 and S21 measurements ? Is the nanovna capable of showing Simultaneous S11 and S21 measurements in one Sweep, like the DG8SAQ VNWA 3EC ? I think I recall something about this requiring two detectors? Beginner. Neal
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Simultaneous S11 and S21 measurements ?
Is the nanovna capable of showing Simultaneous S11 and S21 measurements in one Sweep,
like the DG8SAQ VNWA 3EC ? I think I recall something about this requiring two detectors?
Beginner.
Neal
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Thanks, so the only thing I should do is to multiply the impedance/resistance/reactance values by 6 and they should be correct?
Also looks like the attached picture became very low resolution after uploading. Here are the full screenshots, with marker details:
Cal. 50 ohm:
Cal. 300 ohm:
The antenna should be tuned to around the center of the CCIR FM band, so the 95 MHz match is most likely correct.
I'm not sure what causes the other SWR dips, it's just a regular folded dipole with nothing attached to it. The NanoVNA is right next to it, connected by a piece of PCB with two holes and an SMA connector soldered onto it, like this:
Are these dips present just because it isn't an ideal simulation-like environment?
|
Having calibrated to a 300-ohm standard, then why not multiply the measured
value by 6? I believe there is a place in Saver for a multiplier or
arithmetic.
Note in your 300-ohm cal. presentation of the measured data of S11, VSWR,
you show a dip to 1:1 between 41 and 124 MHz (I can not read the closest
labeled point). That also shows extremely near the center of the Smith
Chart. You have placed the marker at this position. Since you have
calibrated with 300 ohms, the center of the chart is now 300 ohms, not
50-ohms. This is also true of your S11, VSWR data measurement.
This practice is quite common when using the Smith Chart. One can
'normalize' the chart center to about anything within the instruments range
of impedances. Many times, we use a 'normalized chart' and represent the
chart center as 1, unity. Then, in working the problem at hand, one
multiples everything presented on the chart by the characteristic
resistance in which one is working - most times, 50-ohms. In your case,
you are working in a 300-ohm system.
Dave - W?LEV
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On Mon, Feb 17, 2020 at 7:17 PM goscickiw <goscickiw@...> wrote: Is there a way to make the NanoVNA show the SWR as close to 1:1 on 300 ohm
antennas when measuring directly without an impedance transformer, while
still showing correct impedance? I need to measure just the antenna, so
that the cables and impedance transformers don't affect the result. I tried
calibrating with 300 ohm load, but then it shows 300 ohms as 50 ohms when
measuring impedance.
Attached example - FM folded dipole readout with NanoVNA calibrated with
50 ohm load, and with 300 ohm load
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
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Re: Functions of the rocker switch
Yep, I found this behavior after FW update... rocker switch change ¡°center¡± frequency instead of moving marker.. sometimes works weird on my unit and it drives me crazy...
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Is there a way to make the NanoVNA show the SWR as close to 1:1 on 300 ohm antennas when measuring directly without an impedance transformer, while still showing correct impedance? I need to measure just the antenna, so that the cables and impedance transformers don't affect the result. I tried calibrating with 300 ohm load, but then it shows 300 ohms as 50 ohms when measuring impedance.
Attached example - FM folded dipole readout with NanoVNA calibrated with 50 ohm load, and with 300 ohm load
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Re: Android app cable not working!
As I understand this, if a cable can communicate the phone with a PC, it cannot be used with a phone. A "normal" cable is due for connecting the PC, as a host, with a peripheral, being it a disk, a phone or the nano. For using a phone as a host you must use an "On The Go" cable, that forces the phone to behave as a host, being the other side a disk or the nano to act as the peripheral.
For the guys that uses a TV dongle as a V-UHF receiver connected to a PC, there is an APP that works in a phone and in this case you also need to use an OTG cable.
Regards,
Ignacio EB4APL
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El 17/02/2020 a las 19:06, Kayak escribi¨®: Thank you, I wasn't enabling that flag (didnt see the documentation,
moving too fast and assumed the s/w would provide a dialog about any
settings, my bad)
So the flag is set in the android chrome, confirmed, restarted android
chrome, same error "No compatible devices found". I repeated the
process on a clean LG Aristo 2 phone, same result.
Now do you suppose I should consider a somehow incompatible cable?
Cant really be anything else that I know of. The port communicate with
the pc.
As recommended in the documentation on github (which I would probably
never have found) I ordered a OTG usb-c to usb A adapter cable. Chose
this one, amazon.com/Anker-Adapter-Converts-Technology-Compatible/dp/B01COOQIKU
Thanks for the replies and help. Got to be something simple here...
On Mon, Feb 17, 2020 at 12:21 PM hwalker <herbwalker2476@...> wrote:
On Mon, Feb 17, 2020 at 09:07 AM, Kayak wrote:
I went to your web app online with my samsung (j7 prime) and still "no compatible devices found"
==============================================================
Kayak,
The Samsung (j7 prime) should at least work with the web app online.
These are the developer's instructions from :
1. Enable flag: chrome://flags/#enable-experimental-web-platform-features
2. Access to .
3. Connect your NanoVNA to USB port.
4. Click [CONNECT] and select the device.
- Herb
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Re: Android app cable not working!
On Mon, Feb 17, 2020 at 05:49 PM, hwalker wrote:
On Mon, Feb 17, 2020 at 09:23 AM, Ronan Daly wrote:
" I use a generic unbranded one that came with a chinese tablet and it works
fine with my Galaxy S7."
====================================================================================
Ronan,
Have you tried the NanoVNA app from the Google Play store with your S7?
That would let Kayak know if he might expect the NanoVNA to work off-line with
his j7 prime or not.
- Herb
Yes the app works fine.
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Re: Android app cable not working!
Thank you, I wasn't enabling that flag (didnt see the documentation,
moving too fast and assumed the s/w would provide a dialog about any
settings, my bad)
So the flag is set in the android chrome, confirmed, restarted android
chrome, same error "No compatible devices found". I repeated the
process on a clean LG Aristo 2 phone, same result.
Now do you suppose I should consider a somehow incompatible cable?
Cant really be anything else that I know of. The port communicate with
the pc.
As recommended in the documentation on github (which I would probably
never have found) I ordered a OTG usb-c to usb A adapter cable. Chose
this one, amazon.com/Anker-Adapter-Converts-Technology-Compatible/dp/B01COOQIKU
Thanks for the replies and help. Got to be something simple here...
toggle quoted message
Show quoted text
On Mon, Feb 17, 2020 at 12:21 PM hwalker <herbwalker2476@...> wrote:
On Mon, Feb 17, 2020 at 09:07 AM, Kayak wrote:
I went to your web app online with my samsung (j7 prime) and still "no compatible devices found"
==============================================================
Kayak,
The Samsung (j7 prime) should at least work with the web app online.
These are the developer's instructions from :
1. Enable flag: chrome://flags/#enable-experimental-web-platform-features
2. Access to .
3. Connect your NanoVNA to USB port.
4. Click [CONNECT] and select the device.
- Herb
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I'm running nanoVNA @edy555 version firmware v0.5.4. Is there the ability to save the state of the nanoVNA over power cycles? I have the battery installed, and I can recall 0-4, but not save anything that could be recalled. Am I missing something? I have only had this for a few days, so that could be possible.
73 G8KUW
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Oristo
Alberto I2PHD
Neal AB6G
goscickiw
