|
I'm a little bit disappointed; i measured a CW 100MHz output from my NanoVNA-H received one week ago.
The reference of my frequency meter is a 5MHz G3RUH GPSDO and i get a 99.99144 MHz (~ -85.5 ppm error);
same result with a calibrated SDR receiver. I'm not able to measure the TCXO output frequency.
At my non professional point of vue, 2 possibilities:
-1- The TCXO is totally out of specifications.
-2- Something is wrong with the Si5351A-B-GT frequency programming command.
Can somebody explain what is wrong with my NanoVNA ?
Thank you in advance for your help.
Rudi
|
Just by curiosity, i entered a CW value of 100.0086 Mhz and i measured 100.00002 MHz.
It should be a solution with Si5351 programmation but, after reading a lot of related information,
i don't find a solution.
Rudi
|
With a loop, i was able to measure the TCXO frequency and found
25.997748 MHz instead of 26MHz ! This error correspond to ~ -86ppm,
not too far of the output error of -85.5 ppm at 100MHz CW !
As i'm not able to replace the TCXO (+/- 2.5 ppm Max according the data-sheet...),
i must look for an other solution. Unit return to the vendor "Wish" seems impossible.
A 1st and last experience, not with NanoVNA-H but Wish !
Rudi
|
The NanoVNA-H we produced should not have such a large deviation. Can we provide PCB pictures and test pictures? If it is the version we made, we can provide a new one for free.
|
|
|
As the TCXO frequency is out of tolerances, it's certainly a defect component.
As i wrote, i ordered the Nanovna-H at "Wish". I've read, but too late, that this was not the best solution...
The solution, for me, is to ask to a known friend, well equipped and trained for small SMD components replacement
to do the work. Now, i must find an equivalent or compatible component.
Rudi
toggle quoted message
Show quoted text
Le 21.05.2020 ¨¤ 17:41, hugen@... a ¨¦crit?: The NanoVNA-H we produced should not have such a large deviation. Can we provide PCB pictures and test pictures? If it is the version we made, we can provide a new one for free.
|
On Thu, May 21, 2020 at 09:06 AM, Rudolf Schaffer wrote:
As the TCXO frequency is out of tolerances, it's certainly a defect
component.
DiSlord suggested the error could be due to the firmware. What version are you running? Roger
|
No it look like hardware problem (or measure frequency problem) It possible fix by software need redefine // XTAL frequency on si5351
#define XTALFREQ 26000000U To current XTAL frequency and rebuild Or replace XTAL
|
Roger,
The HW version is 3.4
and FW version: 0.4.5-1-gfbbceca.
As i wrote before:
"
With a loop, i was able to measure the TCXO frequency and found
25.997748 MHz instead of 26MHz ! This error correspond to ~ -86ppm,
not too far of the output error of -85.5 ppm at 100MHz CW !
"
According to the schematic, (may be not the corresponding one...) the oscillator is a TCXO;? i don't
see a connection to a DAC or DC source, as for a TVCXO or VCXO. A pin, labelled AFC, seems to be grounded,
as i saw on the schematic. I searched on the WEB for a component
corresponding to the hard to read reference written on the component but i found nothing.
I'm far to be a specialist, but for me, the TCXO is far away from tolerance and defect.
I'm sure it should be compensated by software, but i don't like this solution in my case with a -85.5 ppm error.
As i wrote before, i will find a compatible component (frequency, tolerances, foot-print,etc) and ask to
a friend of me to replace it.
Regards,
Rudi
toggle quoted message
Show quoted text
Le 21.05.2020 ¨¤ 19:14, Roger Need via groups.io a ¨¦crit?: On Thu, May 21, 2020 at 09:06 AM, Rudolf Schaffer wrote:
As the TCXO frequency is out of tolerances, it's certainly a defect
component.
DiSlord suggested the error could be due to the firmware. What version are you running?
Roger
|
Thank you for your message.
I'm sure of my correct measurements:
-1- The relatives frequencies errors are ~ equal on the CW output at 100MHz
and direct TCXO (^-86 ppm)
-2- The reference of my frequency meter is furnished with the output of a well locked G3RUH GPSDO.
As written before, i will choose your 2nd solution, replacing the TCXO with a new and verified one.
Regards,
Rudi
toggle quoted message
Show quoted text
Le 21.05.2020 ¨¤ 19:41, DiSlord a ¨¦crit?: No it look like hardware problem (or measure frequency problem)
It possible fix by software need redefine
// XTAL frequency on si5351
#define XTALFREQ 26000000U To current XTAL frequency and rebuild
Or replace XTAL
|
It would be nice to have a menu option to calibrate the frequency. It is easy to adjust the Si5351A output frequency, all libraries for it include this function.
73, Mike AF7KR
|
Hi Mike,
I agree totally ! It would be very useful in my case, waiting to replace the TCXO.
For the moment, i'm obliged to multiply the desired frequency by 1.0000855 to compensate
the too large error of the TCXO.
73 QRO,
Rudi, HB9ARI
toggle quoted message
Show quoted text
Le 22.05.2020 ¨¤ 17:38, vbifyz a ¨¦crit?: It would be nice to have a menu option to calibrate the frequency. It is easy to adjust the Si5351A output frequency, all libraries for it include this function.
73, Mike AF7KR
|
I don't understand this TXCO error concern. Is the NanoVNA being used as a precision freq counter?
If you are using it for measurements between 2 freqs, what is the % of precision you are expecting from an instrument that costs less than $100.00 USD? Most test equipment is ¡À3%. I believe these are well within that.
?___
Sent from my two way wrist watch
73 de W3AB/GEO?
toggle quoted message
Show quoted text
On May 22, 2020, 10:27, at 10:27, Rudolf Schaffer <rudolf.schaffer@...> wrote: Hi Mike,
I agree totally ! It would be very useful in my case, waiting to
replace
the TCXO.
For the moment, i'm obliged to multiply the desired frequency by
1.0000855 to compensate
the too large error of the TCXO.
73 QRO,
Rudi, HB9ARI
Le 22.05.2020 ¨¤ 17:38, vbifyz a ¨¦crit?:
It would be nice to have a menu option to calibrate the frequency. It is easy to adjust the Si5351A output frequency, all libraries for it
include this function.
73, Mike AF7KR
|
Hello,
For the moment, my friend has no access to the labo for component replacement (virus).
I would try your XTALFREQU modification but i'm not able to modify and recompile your software.
How can i proceed, may be with an other FW including the OFFSET command not active
on my NanoVNA-H ?
Thank you for helping me.
Regards,
Rudi
toggle quoted message
Show quoted text
Le 21.05.2020 ¨¤ 19:41, DiSlord a ¨¦crit?: No it look like hardware problem (or measure frequency problem)
It possible fix by software need redefine
// XTAL frequency on si5351
#define XTALFREQ 26000000U To current XTAL frequency and rebuild
Or replace XTAL
|
Try this firmware, just quick build vs XTALFREQ 25997748
|
|
|
This is a different device.
|
30Hz in 100MHz.
That is just 0.00003% low in frequency.
For the money we spent, why would anybody not be satisfied with that?
I'm still happy with the accuracy of my Grid Dip Meter.
73, Alek, VK6APK.
toggle quoted message
Show quoted text
On 23/05/2020 6:13 pm, Aleksander Shalygin wrote: 100 mHz, 299 mHz.
|
Thank you very much DiSlord for your help and work.
I will install this file this afternoon and inform you for the result.
Regards,
Rudi
toggle quoted message
Show quoted text
Le 23.05.2020 ¨¤ 10:43, DiSlord a ¨¦crit?: Try this firmware, just quick build vs XTALFREQ 25997748
|
Hi DiSlord,
I installed DfuSe, connected to the NanoVNA after "Reset and enter DFU" activated;
on the DfuSe screen i have 2 Targets options:
-1- 00 Internal Flash 64 sectors or
-2- 01 Option Bytes??? 1 sector.
What is the correct target ?
Thank you for your help.
Rudi
toggle quoted message
Show quoted text
Le 23.05.2020 ¨¤ 10:43, DiSlord a ¨¦crit?: Try this firmware, just quick build vs XTALFREQ 25997748
|
Roger Need
GEO BADGER
Aleksander Shalygin
