With the help you can see what commands are available in the given version.
--
*** nothing is permanent only change ( ) ***
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Good afternoon Gents.
Ive just updated my firmware and manage to connect to the vna with putty
however when I enter the command vbat_offset 150
I get the response vbat_offset?
Any clues ?
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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
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Re: [Measuring] Is there an easy way to measure balun loss?
I did this about 2 years ago similar to Roger Need's second link. On the output of the 1:49 balun I connected a 2400 ohm resistor and in series with this resistor on its ground end I connected an HP power meter. The total load is then 2450 ohms. If the 1:49 transformer has a 0 dB loss the the power meter would measure 16.9 dB below the input power. Anything higher than 16.9 dB down due to the loss in the 1:49 transformer (it is not an autotransformer or and unun, BTW.....it is a conventional transformer with a primary and secondary winding). This based on the ideal S21 = 10 x log (50/2450) = -16.902 dB. You can do the same with a 1:9 transformer (10 x log (50/450) etc.. When I received my Nanovna back last August, there was good agreement in the loss measurement against the HP 435B with an HP8482 power sensor. This is how I determined the loss of a 1:49 EFHW transformer to be 1 to 1.5 dB depending on the freq. A resistance of 2450 ohms is far from what an EFHW antenna's feed point Z is but close enough for a ball park check. A back to back test had fairly good agreement. 73
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Bill,
That was a deleted word, not mispelled. Prolly due to my phat phingers.
?___
Sent from my two way wrist watch
73 de W3AB/GEO?
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On May 21, 2020, 12:53, at 12:53, Bill Cromwell <wrcromwell@...> wrote: Hi Geo,
In my two way wrist watch I have restricted the spell-checker to merely
suggesting by underline any words it thinks are wrong and it is not
allowed to "autocorrect". Sometimes it underlines correctly and other
times displays it's puny lexicon by underlining correctly spelled
words.
I mever nake big misteaks.
73,
Bill KU8H
On 5/21/20 3:37 PM, GEO BADGER via groups.io wrote:
Should NOT flake off. My droid won that battle. Ugh!
?___
Sent from my two way wrist watch
73 de W3AB/GEO?
--
bark less - wag more
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Hi Ed It is quite normal what you see. Please note that the number of point are only 100 so for the span used 50MHz you have a point for each 0.5MHz. Reduce the span to e.g. 140 to 150 MHz and see for every 100KHz the impedance / SWR. The load are OK it is not what you concern should be, It do not think you Ohm meter are accurate enough to determine the very exact DC resistance and will only create a very little SWR contribution. I would guess you antenna does not have 50ohm impedance on 145MHz. The oscillation you see are natural for reflection from the antenna which is wandering forth and back in the cable. Kind regards Kurt -----Oprindelig meddelelse----- Fra: [email protected] < [email protected]> P? vegne af ed@... Sendt: 21. maj 2020 07:35 Til: [email protected]Emne: [nanovna-users] Calibration issue causing ripples in SWR? #calibration After calibrating, I connected my nanovna to my VHF antenna via a brand new 75 foot length of 50ohm DX400MAX coax. The SWR measurement oscillates up and down every 4MHz or so (see attached). These correspond exactly to the half-wavelength harmonics of the cable. Looking at the smith chart, it is clear that the impedance is tracing a circle around about 45 ohms rather than the constant-SWR circle centered at 50 ohms, resulting in a frequency-dependent SWR. Is there is a good way to determine whether this is a problem with my nanovna, with the calibration standard, or with the cable? One note: the calibration standard load measures 51 ohms DC resistance, which seems like a problem to me. Should my standard be exactly 50 ohms dc resistance?
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Hi Geo,
In my two way wrist watch I have restricted the spell-checker to merely suggesting by underline any words it thinks are wrong and it is not allowed to "autocorrect". Sometimes it underlines correctly and other times displays it's puny lexicon by underlining correctly spelled words.
I mever nake big misteaks.
73,
Bill KU8H
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On 5/21/20 3:37 PM, GEO BADGER via groups.io wrote: Should NOT flake off. My droid won that battle. Ugh!
?___
Sent from my two way wrist watch
73 de W3AB/GEO?
--
bark less - wag more
|
Should NOT flake off. My droid won that battle. Ugh!
?___
Sent from my two way wrist watch
73 de W3AB/GEO?
toggle quoted message
Show quoted text
On May 21, 2020, 12:29, at 12:29, "GEO BADGER via groups.io" <w3ab@...> wrote: Jason,
As an ex-employee of M/A-COM I can vouch for what you learned. We made
special connectors for the test equipment companies, HP, Wiltron and
such. The plating should flake off any OS connector.
BeCu is not necessarily dangerous with standard machining practices
because it produces large chips & not dust during the machining
process.
A couple of other companies I worked for used BeO. It an excellent
electrical insulator and possesses the highest thermal conductivity of
commercial ceramics. We needed that for the high power circuits we
designed. It was machined under water due the dust generated by
grinding & polishing.
IMHO, the frequencies that the NanoVNA operates at & the precision we
require are not compromised by good connectors & operating practices.
These devices should not be compared to a HP VNA. They are ideal for
amateur radio use.
I use push-SMA connector savers with excellent repeatability. I believe
they were made by Adams-Russell, another M/A-COM company.
?___
Sent from my two way wrist watch
73 de W3AB/GEO?
On May 21, 2020, 12:01, at 12:01, fishtronics <fishtronics@...>
wrote:
Using the SMA-M/SMA-F adapters as connector savers like I think you
show, Stan, is a very good idea. Even very high quality SMA connectors
(>$50 each) degrade in match very quickly. Cheap ones with only 2 jaws
on the center conductor are pretty much worthless for repetitive use. I
was once told by the ME at Omni-Spectra their SMAs were rated to meet
spec for the initial connection only! I am getting a bunch and will
swap them out as soon as any gold flaking or wear is apparent under
magnification. Most of the cheaper SMA connectors from China look to me
to have plain brass center contacts which will not apply any contact
pressure after the first mating. A capacitive gap results. The only
inexpensive SMA-M/SMA-F adapter I can find with a Beryllium center
conductor is the Cal Test CT3673. The only reason to use BeCu which
costs more and is poisonous to machine is if they heat treat it, to
make the jaws springy. I don't know whether there are more than 2 jaws
to the F pin. Better ones have more, but at < 1GHz it probably won't
make any difference untll the jaw loses its spring. I have a question
into the tech support to ask about it. Data sheet kere:
.
They are dirt cheap at
Amazon:.
Jason NJ7K
|
Jason,
As an ex-employee of M/A-COM I can vouch for what you learned. We made special connectors for the test equipment companies, HP, Wiltron and such. The plating should flake off any OS connector.
BeCu is not necessarily dangerous with standard machining practices because it produces large chips & not dust during the machining process.
A couple of other companies I worked for used BeO. It an excellent electrical insulator and possesses the highest thermal conductivity of commercial ceramics. We needed that for the high power circuits we designed. It was machined under water due the dust generated by grinding & polishing.
IMHO, the frequencies that the NanoVNA operates at & the precision we require are not compromised by good connectors & operating practices. These devices should not be compared to a HP VNA. They are ideal for amateur radio use.
I use push-SMA connector savers with excellent repeatability. I believe they were made by Adams-Russell, another M/A-COM company.
?___
Sent from my two way wrist watch
73 de W3AB/GEO?
toggle quoted message
Show quoted text
On May 21, 2020, 12:01, at 12:01, fishtronics <fishtronics@...> wrote: Using the SMA-M/SMA-F adapters as connector savers like I think you
show, Stan, is a very good idea. Even very high quality SMA connectors
(>$50 each) degrade in match very quickly. Cheap ones with only 2 jaws
on the center conductor are pretty much worthless for repetitive use. I
was once told by the ME at Omni-Spectra their SMAs were rated to meet
spec for the initial connection only! I am getting a bunch and will
swap them out as soon as any gold flaking or wear is apparent under
magnification. Most of the cheaper SMA connectors from China look to me
to have plain brass center contacts which will not apply any contact
pressure after the first mating. A capacitive gap results. The only
inexpensive SMA-M/SMA-F adapter I can find with a Beryllium center
conductor is the Cal Test CT3673. The only reason to use BeCu which
costs more and is poisonous to machine is if they heat treat it, to
make the jaws springy. I don't know whether there are more than 2 jaws
to the F pin. Better ones have more, but at < 1GHz it probably won't
make any difference untll the jaw loses its spring. I have a question
into the tech support to ask about it. Data sheet kere:
.
They are dirt cheap at
Amazon:.
Jason NJ7K
|
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
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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
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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
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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
|
Using the SMA-M/SMA-F adapters as connector savers like I think you show, Stan, is a very good idea. Even very high quality SMA connectors (>$50 each) degrade in match very quickly. Cheap ones with only 2 jaws on the center conductor are pretty much worthless for repetitive use. I was once told by the ME at Omni-Spectra their SMAs were rated to meet spec for the initial connection only! I am getting a bunch and will swap them out as soon as any gold flaking or wear is apparent under magnification. Most of the cheaper SMA connectors from China look to me to have plain brass center contacts which will not apply any contact pressure after the first mating. A capacitive gap results. The only inexpensive SMA-M/SMA-F adapter I can find with a Beryllium center conductor is the Cal Test CT3673. The only reason to use BeCu which costs more and is poisonous to machine is if they heat treat it, to make the jaws springy. I don't know whether there are more than 2 jaws to the F pin. Better ones have more, but at < 1GHz it probably won't make any difference untll the jaw loses its spring. I have a question into the tech support to ask about it. Data sheet kere: . They are dirt cheap at Amazon:.
Jason NJ7K
|
Dr. Kirkby is right, as I can confirm from my own experience. Last year I wanted to do a RL measurement o find the losses of several lengths (up to 25 m) of leftover coaxial cables on all amateur bands from 2 m up to 13 cms IN ONE GO. So I set my HP8753C to a span of something like 100 to 2500 MHz and measured the RL of each cable on one end while leaving the other end open (or shorting it), with default settings of the 8753. Or maybe I used 401 iso 201 points. Anyway, I then noticed unexplainable steps along the way in the measured RL curves. This turned out to be simply a matter of the default sweep time being too short. I haven't tried a similar thing with my NanoVNA-F up to 1.5 GHz, and maybe I will just for curiosity. But you can't change the sweep time of a NanoVNA anyway, to my early knowledge of the device.
73's Hans PA3AZA
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Sounds like a perfect excuse to buy a 3D printer!
73 Ed N5KZW
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Re: NanoVNA dealers in Europe?
Thanks for all the suggestions!
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On Wed, May 20, 2020 at 07:15:33AM -0700, ian.bowman70 via groups.io wrote: I got mine from Mirfield Electronics, you could also try Canny Components.
Ian
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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
|
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
|
Re: [Measuring] Is there an easy way to measure balun loss?
On Thu, May 21, 2020 at 06:35 AM, <gaionim@...> wrote:
try to see
and
Interesting way to measure balun loss with a single balun and a VNA. Thank you for posting this information. Roger
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Re: Looking for firmware with battery indicator, 1500 and big font
Hi,
Is it posible for add the big CH0 screen info in version 0.7.1-20200321 by edy555 ?
Tnx
Andy - ON7BA
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Re: [Measuring] Is there an easy way to measure balun loss?
I just joined the nanoVNA group a couple of days ago and followed your thread on the balun measurement. If possible, why don¡¯t you measure the scattering params, save the data, build a 3x3 scattering parameter matrix with the data and convert it to mixed signal to get the diff output? See for example . You would need one of the math software tools out there and I understand that practice and theory... have some issues to get along! but eventually they should go hand in hand. Just a suggestion.
Luciano
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Gyula Molnar
Allen James M0PPX
GEO BADGER
Kurt Poulsen
Roger Need