When I measure 50 Ohm coaxial impedance with the 1/8 wave method, I always get 50 Ohms. I tried some 75 Ohm cable and still get 50 Ohms!
When I use my old method of adjusting the termination it works fine and I get the expected 75 Ohms.
I think I got a reading at 1/8 wave of roughly 200 pF and 15 MHz, if memory serves. So either the method is flawed or I am doing something wrong. What I do is sweep the frequency to the point where the Smith chart trace is at the bottom of the chart, or one-eighth wave out (open end), and read the figures on the screen. Then I compute the capacitive reactance.
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Re: Nano VNa H4 saving settings
Thanks Herb, that works perfectly.
I saw the 'save'menu item but as it was under 'cal' I wongfully assumed that it would save just the calibration.
I have just saved a cal and settings for 1.6 - 30MHz. which I use mostly as the default into location 0.
When I switch it on, that is now recalled automatically, so perfect, i'll now save the calibration for various bands that I use in the remaining memories and then manually recall them as and when I require them
Regards
Tony
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Re: Wireless control of NanoVNA
Hugen's H4 unit with the 4 inch display already has a serial port available in addition to the USB for use with additional peripherals like wifi and Bluetooth dongles.?
The only problem at this time is none of the devs have enabled them just yet but its just a matter of time now.?
On Sat, 25 Jan 2020 at 10:39 PM, gmendenh1947<W8GNM@...> wrote: Here is a feature idea for the next? update of the NanoVNA design.? If the NanoVNA had a WiFi transceiver on board in addition to the USB port, so it could be controlled remotely by NanoVNA Sharp, NanoVNA Saver, or similar applications.
This would allow the NanoVNA to be attached directly to the feedpoint of a multiband antenna and hoisted with the antenna into the operating position, thereby eliminating the complication of transmission line normalizations over multiple frequency bands.? The unit could be programmed remotely and the data could be captured remotely.
I would be willing to pay a significant premium for this capability.
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Wireless control of NanoVNA
Here is a feature idea for the next update of the NanoVNA design. If the NanoVNA had a WiFi transceiver on board in addition to the USB port, so it could be controlled remotely by NanoVNA Sharp, NanoVNA Saver, or similar applications.
This would allow the NanoVNA to be attached directly to the feedpoint of a multiband antenna and hoisted with the antenna into the operating position, thereby eliminating the complication of transmission line normalizations over multiple frequency bands. The unit could be programmed remotely and the data could be captured remotely.
I would be willing to pay a significant premium for this capability.
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On Sat, Jan 25, 2020 at 03:24 PM, Nigel Gunn, G8IFF/W8IFF wrote:
" Or recomment they use Linux and not Windows.
Then they don't need any ST files. They will already have the needed software."
==============================================
Nigel,
If you've been following some of the Linux installation issues over the last few weeks, then you know that certain flavors of Linux also have their difficulties. Some Linux users have reported needing to temporarily switch over to a windows machine to update their NanoVNA firmware. All operating systems have their plus and minuses.
Windows 10 has the needed drivers included. Earlier versions of Windows require the user to manually install the drivers.
- Herb
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Re: nanovna-users]NanoVNA-H4 2Port calibrationof
On Sat, Jan 25, 2020 at 03:58 PM, Jos Stevens wrote:
I did what you suggested , removed the portsavers re-calibrated the standalone VNA,the result was better then before 0.00 db, +0.12 and -0.25 at 50k, 750M and 1500M. Then I calibrated in Nanovna-Saver using 4 segs like you, Before was better, and After was an ideal straight line at 0 dB!
==============================================================================
Good job Jos. I initially had problems with Rune's calibration module but after he posted that you needed to start the module from a good calibration on the NanoVNA saved to "SAVE 0" it has always worked well for me. I still use the ideal models because I hate entering numbers that I don't fully understand.
Rune's NanoVNA-saver application has been working great with the NanoVNA-H4 thus far. The screen saver doesn't work because different code is required for the 4" display, and NanoVNA-saver reports the unit as a NanoVNA-H which may mean the hugen will need to change the -H4 identifier in firmware to help developers differentiate it.
- Herb
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Re: Cheap calibration loads
#parts
On Sat, Jan 25, 2020 at 03:10 PM, Larry Benko wrote:
Making reasonable quality loads is not difficult.? See if interested.
==========================================================================
Larry,
I've made a few like that myself and they all perform well up to 1 GHz. My main reason for the post was to show that if you measure a termination with a dc meter and have it read 50.01 ohms that it isn't necessarily good for use at VHF or UHF frequencies. A lot of inexperienced users don't understand that, but seeing a poorly assembled terminator makes the concept easier to remember.
- Herb
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Re: nanovna-users]NanoVNA-H4 2Port calibrationof
Herb,
I did what you suggested , removed the portsavers re-calibrated the standalone VNA,the result was better then before? 0.00 db, +0.12 and -0.25 at 50k, 750M and 1500M. Then I calibrated in Nanovna-Saver using 4 segs like you, Before was better, and After was an ideal straight line at 0 dB!
It's late now, tomorrow I will investigate wat caused the strange behaviour , the portsaver or whatever, I will let you know the result. anyhow many thanks for your help.
Jos
Op 25-1-2020 om 22:55 schreef hwalker:
toggle quoted message
Show quoted text
On Sat, Jan 25, 2020 at 12:37 PM, Jos Stevens wrote:
yes I did use the calibration wizard and I have done it so often that I can do it blindfolded..
The only thing different is that For the H4 I used portsavers and used one of the cables that were in the box of the -H4, the firmware is still from the first of Januari 2020, I did not upgrade yet because I learned that there are problems with the new firmware.
Anyhow you say that you have no problems, I'm using NanoVNA-Saver 0.2.2.1, the latest version as far as I know. I hardly can believe that the problem is in the hardware, because the hardware stand alone shows "Ch1 Logmag 10 dB/-1.42 dB @ 50 kHz" , -0.07 dB @ 810Mhz and -1.55 dB @ 1500 MHz after a 101 point calibration. A minute ago I ran the calibration again on NanoVNA-Saver and attached the pictures before and after pressing "Apply".
================================================================================================
Jos,
I re-did my calibration trying to match as closely as possible the settings you used except I had already set things up before I saw your follow-up regarding the number of segments you used. I used 4 segments (404 pts) but that shouldn't matter.
The main difference I see is that I had already cal'd my NanoVNA-H from 50k-1GHz and just changed my stop frequency to 1.5GHz to match yours. Even so my "before" S21 plot (red trace in attachment) looks better than your "before" s21 plot. If you did a 50k-1.5GHz calibration on your NanoVNA-H4 and stored it in Save 0, your before s21 plot should look a lot better than it does. The black trace in the attached photo is my s21 thru measurement after calibration.
I believe if you go into NanoVNA-saver with a good 50k-1.5GHz SOLT calibration, saved to SAVE 0 on your NanoVNA-H4, that your issue should resolve itself.
- Herb
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Or recomment they use Linux and not Windows.
Then they don't need any ST files. They will already have the needed software.
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Was my First purchase from China a mistake? This is a no battery clone I assume. First session I used Saver 0.2.2-1 to do a calibrate.
My device is now non responsive. I do see the 'Disconnect' on Saver but no movement in any process. The VNA screen shows
NanoVNA gen111.taobao.com in center, left - C0 D R S, START 2.0000 Mhz, Stop 55.000MHz . There are no touch screen actions. The USB LED is 1PPS and the process LED is on continus. I have not been able to get any change in display even with a power off cycle.
Is there any hope that I might restore this unit?
John
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Re: Cheap calibration loads
#parts
Herb,
Making reasonable quality loads is not difficult.? See if interested.
Larry, W0QE
toggle quoted message
Show quoted text
On 1/25/2020 1:34 PM, hwalker wrote: Ever wonder why some 50 ohm loads are reasonably priced, look great at dc, but quickly veer off 50 ohms at higher frequencies? Take a look at the attached photo, courtesy of one of the Russian NanoVNA boards, and wonder no more. The ground lead even looks it is compression contact instead of soldered.
- Herb
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Re: Cheap calibration loads
#parts
On Sat, Jan 25, 2020 at 02:31 PM, Aldo Cugnini wrote:
68 ohms (resistance) will give you a VSWR of 1.36, so it's very nearly inspec, according to the soec sheet you linked.
=============================================
Aldo,
If you read the spec's closely its:
VSWR: 1.05+0.008f(GHz) max@...,
1.30max@...
So in the provided 50k - 1 GHz plots, the return loss should be no smaller than 30 dB (~VSWR 1.06).
- Herb
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Re: Cheap calibration loads
#parts
68 ohms (resistance) will give you a VSWR of 1.36, so it's very nearly in
spec, according to the soec sheet you linked.
-. Aldo
toggle quoted message
Show quoted text
On Sat, Jan 25, 2020, 4:09 PM <cosbug@...> wrote:
Hello All,
Could someone advise if these SMA terminators are good ?
I've done a resistance check at DC using multimeter and it's shown 68 Ohms
(too high by me, should be lower).
Secondly, I've attached to VNA (properly calibrated with other known good
50 Ohm SMA) and the result is:
1. At frequencies lower than 100Mhz SWR is 1.3.
2. In 1Ghz range has significant capacitance impedance.
The item is rated DC-18Ghz TRM-2444-M0-SMA-02 (specs https:
www.mouser.co.uk/datasheet/2/643/pi-CCS-MW-TRM-2444-M0-SMA-02-1312942.pdf)
Am I doing something wrong or terminators are defective ?
Pictures attached.
Regards,
Constantin
|
Re: Cheap calibration loads
#parts
On Sat, Jan 25, 2020 at 01:08 PM, <cosbug@...> wrote:
Could someone advise if these SMA terminators are good ?
I've done a resistance check at DC using multimeter and it's shown 68 Ohms (too high by me, should be lower).
Secondly, I've attached to VNA (properly calibrated with other known good 50 Ohm SMA) and the result is:
1. At frequencies lower than 100Mhz SWR is 1.3.
2. In 1Ghz range has significant capacitance impedance.
The item is rated DC-18Ghz TRM-2444-M0-SMA-02 (specs https: www.mouser.co.uk/datasheet/2/643/pi-CCS-MW-TRM-2444-M0-SMA-02-1312942.pdf)
Am I doing something wrong or terminators are defective ?
===========================================================
Constantin from your attached photos you have a reason to be suspect. The low cost terminator that came with my NanoVNA-H4 has a return loss of over 40 dB up to 1 GHz, and the Midwest Microwave terminator in your photo is showing a return loss of 20 dB at some frequencies. That's pretty poor and definitely outside the specifications of the device.
I have come across similar Midwest Microwave terminators at swap fests and I cherry pick them using the NanoVNA I always carry with me. The sellers aren't very thrilled because they are left with known subpar terminations on their table while I walk away with the in spec devices.
- Herb
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Re: nanovna-users]NanoVNA-H4 2Port calibrationof
On Sat, Jan 25, 2020 at 12:37 PM, Jos Stevens wrote:
yes I did use the calibration wizard and I have done it so often that I can do it blindfolded..
The only thing different is that For the H4 I used portsavers and used one of the cables that were in the box of the -H4, the firmware is still from the first of Januari 2020, I did not upgrade yet because I learned that there are problems with the new firmware.
Anyhow you say that you have no problems, I'm using NanoVNA-Saver 0.2.2.1, the latest version as far as I know. I hardly can believe that the problem is in the hardware, because the hardware stand alone shows "Ch1 Logmag 10 dB/-1.42 dB @ 50 kHz" , -0.07 dB @ 810Mhz and -1.55 dB @ 1500 MHz after a 101 point calibration. A minute ago I ran the calibration again on NanoVNA-Saver and attached the pictures before and after pressing "Apply".
================================================================================================
Jos,
I re-did my calibration trying to match as closely as possible the settings you used except I had already set things up before I saw your follow-up regarding the number of segments you used. I used 4 segments (404 pts) but that shouldn't matter.
The main difference I see is that I had already cal'd my NanoVNA-H from 50k-1GHz and just changed my stop frequency to 1.5GHz to match yours. Even so my "before" S21 plot (red trace in attachment) looks better than your "before" s21 plot. If you did a 50k-1.5GHz calibration on your NanoVNA-H4 and stored it in Save 0, your before s21 plot should look a lot better than it does. The black trace in the attached photo is my s21 thru measurement after calibration.
I believe if you go into NanoVNA-saver with a good 50k-1.5GHz SOLT calibration, saved to SAVE 0 on your NanoVNA-H4, that your issue should resolve itself.
- Herb
|
Re: Cheap calibration loads
#parts
Hmmm...looks like a Nano-Cantenna ;-)
On Sat, 25 Jan 2020 at 3:34 PM, hwalker<herbwalker2476@...> wrote: Ever wonder why some 50 ohm loads are reasonably priced, look great at dc, but quickly veer off 50 ohms at higher frequencies?? Take a look at the attached photo, courtesy of one of the Russian NanoVNA boards, and wonder no more.? The ground lead even looks it is compression contact instead of soldered.
- Herb
|
Re: Cheap calibration loads
#parts
Hello All,
Could someone advise if these SMA terminators are good ?
I've done a resistance check at DC using multimeter and it's shown 68 Ohms (too high by me, should be lower).
Secondly, I've attached to VNA (properly calibrated with other known good 50 Ohm SMA) and the result is:
1. At frequencies lower than 100Mhz SWR is 1.3.
2. In 1Ghz range has significant capacitance impedance.
The item is rated DC-18Ghz TRM-2444-M0-SMA-02 (specs https: www.mouser.co.uk/datasheet/2/643/pi-CCS-MW-TRM-2444-M0-SMA-02-1312942.pdf)
Am I doing something wrong or terminators are defective ?
Pictures attached.
Regards,
Constantin
|
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
I forgot to mention That I used 10 Segments in NanoVNA-Saver
Jos
Op 25-1-2020 om 21:37 schreef Jos Stevens:
toggle quoted message
Show quoted text
Hi Oristo and Herb,
Thinks for the pictures Oristo, i think they are from the 2.8" NanoVNA-H, my 2.8 -H version works well, this problem is? with my VNA new version H4.
Herb,? yes I did use the calibration wizard and I have done it so often that I can do it blindfolded..
The only thing different is that For the H4 I used portsavers and used one of the cables that were in the box of the -H4, the firmware is still from the first of Januari 2020, I did not upgrade yet because I learned that there are problems with the new firmware.
Anyhow you say that you have no problems,? I'm using NanoVNA-Saver 0.2.2.1, the latest version as far as I know. I hardly can believe that the problem is in the hardware, because the hardware stand alone shows "Ch1 Logmag 10 dB/-1.42 dB @ 50 kHz" , -0.07 dB @ 810Mhz and -1.55 dB @ 1500 MHz after a 101 point calibration. A minute ago I ran the calibration again on NanoVNA-Saver and attached the pictures before and after pressing "Apply".
What can I do more ?
Jos
Op 25-1-2020 om 19:04 schreef hwalker:
On Sat, Jan 25, 2020 at 09:19 AM, Jos Stevens wrote:
" I'm testing my new NanoVna-H4 iusing NanoVNA-Saver and have? a problem doing the 2 port calibration"
=======================================================================================
Jos,
??? I just performed a full 2-port calibration of my NanoVNA-H4 using NanoVNA-Saver and did not experience any problems.? Did you use the calibration wizard?? It should direct you through a full 1-port calibration and then ask if you want to continue with a 2-port calibration.? If you follow the directions and still have problems with s21 results, then you may want to verify that the cables and barrel you are using for through calibration are not defective (it occasionally happens).
- Herb
|
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
Hi Oristo and Herb,
Thinks for the pictures Oristo, i think they are from the 2.8" NanoVNA-H, my 2.8 -H version works well, this problem is? with my VNA new version H4.
Herb,? yes I did use the calibration wizard and I have done it so often that I can do it blindfolded..
The only thing different is that For the H4 I used portsavers and used one of the cables that were in the box of the -H4, the firmware is still from the first of Januari 2020, I did not upgrade yet because I learned that there are problems with the new firmware.
Anyhow you say that you have no problems,? I'm using NanoVNA-Saver 0.2.2.1, the latest version as far as I know. I hardly can believe that the problem is in the hardware, because the hardware stand alone shows "Ch1 Logmag 10 dB/-1.42 dB @ 50 kHz" , -0.07 dB @ 810Mhz and -1.55 dB @ 1500 MHz after a 101 point calibration. A minute ago I ran the calibration again on NanoVNA-Saver and attached the pictures before and after pressing "Apply".
What can I do more ?
Jos
Op 25-1-2020 om 19:04 schreef hwalker:
toggle quoted message
Show quoted text
On Sat, Jan 25, 2020 at 09:19 AM, Jos Stevens wrote:
" I'm testing my new NanoVna-H4 iusing NanoVNA-Saver and have a problem doing the 2 port calibration"
=======================================================================================
Jos,
I just performed a full 2-port calibration of my NanoVNA-H4 using NanoVNA-Saver and did not experience any problems. Did you use the calibration wizard? It should direct you through a full 1-port calibration and then ask if you want to continue with a 2-port calibration. If you follow the directions and still have problems with s21 results, then you may want to verify that the cables and barrel you are using for through calibration are not defective (it occasionally happens).
- Herb
|
Cheap calibration loads
#parts
Ever wonder why some 50 ohm loads are reasonably priced, look great at dc, but quickly veer off 50 ohms at higher frequencies? Take a look at the attached photo, courtesy of one of the Russian NanoVNA boards, and wonder no more. The ground lead even looks it is compression contact instead of soldered.
- Herb
|
Aldo Cugnini
