Disconnected battery still doesn't power up at usb only.
Am 12.10.2021 um 15:11 schrieb Larry Rothman:
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So, your nano is now no longer working at all even after letting it stay off for a while?If you open the housing and remove the battery, see if you can power the unit only from USB. If yes, then the charging/inverter IC may have failed.
On Tuesday, October 12, 2021, 08:34:00 a.m. EDT, Jens M?ller <df9hj@...> wrote:
Hello Larry,
Thank you for your reply.
No that doesn't help.
Am 12.10.2021 um 13:47 schrieb Larry Rothman:
? If you immediately cycle the power off then on, does the unit start running ok again?
? ? ? On Tuesday, October 12, 2021, 04:57:52 a.m. EDT, <df9hj@...> wrote:
? Hi All,
While running NanoVNA H4 with Nano saver via USB abt? 1 hour the NanoVNA H4 screen gets blank.
The NanoVNA H4 desn't reboot, USB connection is also lost, only blue LED beside the mini USB is blinking whlie charging and steady when fully chared.
Any hints?
Thanks folks
vy 73 Jens DF9HJ
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So, your nano is now no longer working at all even after letting it stay off for a while?If you open the housing and remove the battery, see if you can power the unit only from USB. If yes, then the charging/inverter IC may have failed.
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On Tuesday, October 12, 2021, 08:34:00 a.m. EDT, Jens M?ller <df9hj@...> wrote: Hello Larry, Thank you for your reply. No that doesn't help. Am 12.10.2021 um 13:47 schrieb Larry Rothman: ? If you immediately cycle the power off then on, does the unit start running ok again?
? ? ? On Tuesday, October 12, 2021, 04:57:52 a.m. EDT, <df9hj@...> wrote:
?
? Hi All,
?
While running NanoVNA H4 with Nano saver via USB abt? 1 hour the NanoVNA H4 screen gets blank.
The NanoVNA H4 desn't reboot, USB connection is also lost, only blue LED beside the mini USB is blinking whlie charging and steady when fully chared.
Any hints?
Thanks folks
vy 73 Jens DF9HJ
? ?
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Re: Inductor Q Measurement
On Mon, Oct 11, 2021 at 09:21 AM, Andrew Kurtz wrote:
R is quite low and may vary between -2 and 5 ohms.
That "-2" suggests to me that you're not actually reading 'Resistance' there. Resistance should be positive, but Reactance can be in negative ohms. Since high Q _requires_ low R, it's going to be difficult to get good, low resistance connections to your coil - do you solder the cable from the NanoVNA directly to the coil leads/terminals? Any mechanical variability in the metal-to-metal contact there will certainly affect the Q value. says "The Q, or quality, factor of a resonant circuit is a measure of the “goodness” or quality of a resonant circuit. A higher value for this figure of merit corresponds to a more narrow bandwidth, which is desirable in many applications. More formally, Q is the ratio of power stored to power dissipated in the circuit reactance and resistance, respectively: Q = Pstored/Pdissipated = I2X/I2R Q = X/R where: X = Capacitive or Inductive reactance at resonance R = Series resistance. This formula is applicable to series resonant circuits, and also parallel resonant circuits if the resistance is in series with the inductor. This is the case in practical applications, as we are mostly concerned with the resistance of the inductor limiting the Q." Therefore, you could try measuring a resonant circuit, with, as has been mentioned, a high quality capacitor like an air-insulated variable or a mica capacitor to make the resonant circuit. It might be worthwhile to do some research on the Q or quality of various types of capacitors, to ensure that you get a good one. This is an interesting question/'problem and I've often wondered myself about determining the Q of a component or circuit. I've had lots of training and experience as an electronic technician (and ham radio operator), but none in the advanced types of math needed for engineering. -- Doug, K8RFT
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Re: Inductor Q Measurement
Thanks for the feedback, Dave. I didn't mention that COIL is a Windows console program. I gather that wineconsole is necessary. I forgot to mention that a user should first read README.TXT. COIL evolved from a DOS program I wrote 25 years ago. It does not have the usual Windows user interface. Many features are inscrutable, but they are explained in the documentation.
Brian
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Hello Larry,
Thank you for your reply.
No that doesn't help.
Am 12.10.2021 um 13:47 schrieb Larry Rothman:
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If you immediately cycle the power off then on, does the unit start running ok again?
On Tuesday, October 12, 2021, 04:57:52 a.m. EDT, <df9hj@...> wrote:
Hi All,
While running NanoVNA H4 with Nano saver via USB abt? 1 hour the NanoVNA H4 screen gets blank.
The NanoVNA H4 desn't reboot, USB connection is also lost, only blue LED beside the mini USB is blinking whlie charging and steady when fully chared.
Any hints?
Thanks folks
vy 73 Jens DF9HJ
|
If you immediately cycle the power off then on, does the unit start running ok again?
toggle quoted message
Show quoted text
On Tuesday, October 12, 2021, 04:57:52 a.m. EDT, <df9hj@...> wrote:
Hi All,
While running NanoVNA H4 with Nano saver via USB abt? 1 hour the NanoVNA H4 screen gets blank.
The NanoVNA H4 desn't reboot, USB connection is also lost, only blue LED beside the mini USB is blinking whlie charging and steady when fully chared.
Any hints?
Thanks folks
vy 73 Jens DF9HJ
|
Hi All,
While running NanoVNA H4 with Nano saver via USB abt 1 hour the NanoVNA H4 screen gets blank.
The NanoVNA H4 desn't reboot, USB connection is also lost, only blue LED beside the mini USB is blinking whlie charging and steady when fully chared.
Any hints?
Thanks folks
vy 73 Jens DF9HJ
|
Re: Inductor Q Measurement
Brian, thanks very much for the link to your program. It seems to run fine
under Wine in Linux.
Dave
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On Mon, Oct 11, 2021 at 7:10 PM Brian Beezley <k6sti@...> wrote: Andrew, my coil program might interest you. It calculates inductance and Q
for solenoids made of solid or Litz wire. It models a number of wire alloys
and form dielectrics, dielectric ribs or ridges, coil leads, and polygonal
coil shapes. The program can automatically maximize coil Q while keeping
inductance constant.
To validate accuracy, the documentation compares calculated values with
hundreds of inductance and Q measurements made with an HP 4342A Q meter on
dozens of coils of widely varying size and shape. For the coils from my own
junk box, average error magnitude is 2% for inductance and 5% for Q.
The program runs in Windows and is free.
Brian
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Re: Inductor Q Measurement
Andrew, my coil program might interest you. It calculates inductance and Q for solenoids made of solid or Litz wire. It models a number of wire alloys and form dielectrics, dielectric ribs or ridges, coil leads, and polygonal coil shapes. The program can automatically maximize coil Q while keeping inductance constant.
To validate accuracy, the documentation compares calculated values with hundreds of inductance and Q measurements made with an HP 4342A Q meter on dozens of coils of widely varying size and shape. For the coils from my own junk box, average error magnitude is 2% for inductance and 5% for Q.
The program runs in Windows and is free.
Brian
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Re: Inductor Q Measurement
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Re: Inductor Q Measurement
- I am guessing a “trap network” is a series resonant circuit, but I’m not sure.
YES, IT IS A SERIES TRAP NOT A PARALLEL TRAP BUT IT IS IN SHUNT WITH THE OUTPUT, CH1. SO THIS IS A S21 MEASUREMENT. IN AFFECT YOU ARE USING THE VNA AS A SPECTRUM ANALYZER-VOLTMETER AND TAKING A MEASUREMENT OF THE NOTCH DEPTH. IF THE SERIES R OF THE LC NETWORK UNDER TEST IS SMALL, SAY ON THE ORDER OF MILLI-OHMS, YOU WOULD BE SEEING Q's ON THE ORDER OF 300 OR GREATER.
THE MEASUREMENT PROCESS IS JUST THAT OF A VOLTAGE DIVIDER.
- I don’t know what constitutes a “high Q variable capacitor” which your method requires.
IF THE Q OF YOUR COIL IS ASSUMED TO BE 300 OR MORE... YOU ARE GOING TO NEED TO FIND A C LARGER THAN THAT! AIR VARIABLES LIKE BC BAND ARE PRETTY GOOD AND THEIR ARE SOME CERAMIC CAPS THAT HAVE Q'S GREATER THAN 500... SEE AVX CAPS
- When X is 0 at resonance, I get that Rs is all that is left of impedance… but why is that in parallel with the termination resistance?
AGAIN, RS IS IN SHUNT WITH THE LOAD, 50 OHMS, BUT ITS VALUE IS SO SMALL, THAT THE NOTCH DEPTH CREATED IS THAT OF A VERY SMALL SHUNT R. THE END RESULT IS THE NOTCH DEPTH IS DIRECTLY CORRELATED TO THE Rs OF THE LC NETWORK AT RESONANCE.
- Indeed, is “termination resistance” simply the built-in resistance of the meter?
YES, 50 OHMS.
- What is a “notch” and why is there an attenuation depth when series resonance provides a lack of attenuation?
SERIES RESONANCE PROVIDES A LACK OF ATTENUATION IN THE SERIES MODE. BUT THIS HAS IT CONFIGURED IN THE PARALLEL MODE!
- Couldn’t I simply measure the series resonant circuit with the VNA and get a Rs reading directly, but would it be any better than what I get off the coil alone?
YES, BUT THE NUMBERS ARE SOME ARE DIFFICULT TO DISCERN. THIS IS AN INDIRECT WAY TO GET TO A NUMBER WITH SOME IMPROVED ACCURACY. KEEP IN MIND, IF THE FIXTURE LOSSES OR R VALUES ARE NOT SMALL, YOU WILL NOT OBTAIN CORRECT ANSWER.
Parallel Q is the same as series Q at a single frequency. Google the concept of a series to parallel conversion. There you will find the proof and the math. It is not hard, but will require your familiarity of complex numbers.
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Re: General firmware update inquiry
#firmware
There is some older firmware with quite large fonts (see the group wiki) but the latest firmware by DiSlord and Hugen do not have these large fonts. However the font face has been improved to make it more readable. I suggest you try Hugen's 1.0.69. He just released 1.0.70 (tracking DiSlords firmware development) but I don't know what happened with the fonts in this release.
Roger
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Re: Inductor Q Measurement
All good questions Andrew. Standby while I compose some answers.
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Hi all,
sorry for the basic question. I own a regular NanoVNA (small version) which I purchased via Amazon / AllAboutFun. Where can I get a recent firmware update? I am specifically interested in a firmware with bigger front as I need to measure max. 2 values per measurement.
Thanks!
Leo
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Re: Inductor Q Measurement
Great, thanks! I can see that your article addresses the issue nicely, but it also uncovers so many questions a non-EE like me has:
- I am guessing a “trap network” is a series resonant circuit, but I’m not sure.
- I don’t know what constitutes a “high Q variable capacitor” which your method requires.
- When X is 0 at resonance, I get that Rs is all that is left of impedance… but why is that in parallel with the termination resistance?
- Indeed, is “termination resistance” simply the built-in resistance of the meter?
- What is a “notch” and why is there an attenuation depth when series resonance provides a lack of attenuation?
- Couldn’t I simply measure the series resonant circuit with the VNA and get a Rs reading directly, but would it be any better than what I get off the coil alone?
Indeed, possibly related to my third point above: I have never understood why X / Rs = Rp / X. I have played with hypothetical cases, and it seems to not work.
Andy
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On Oct 11, 2021, at 9:24 AM, alan victor <avictor73@...> wrote:
see msg #23812. Also type in Q measurement to the search box.
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Re: Inductor Q Measurement
see msg #23812. Also type in Q measurement to the search box.
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I am neither a programmer nor trained in electronics, but I am having a great time using my nanoVNA-H4 with my homemade crystal radio. I measure S11 using only CH0, and the results I get for Smith chart, inductance, and reactance seem about right and work well when I use them for things like predicting tuned frequency given a know capacitance.
However, I believe I have no way to estimate Q = X / R for my coils, because R is quite low and may vary between -2 and 5 ohms. That variability may not be all that bad for a $90 instrument, but it can’t be used for Q! I am hoping you EE types may suggest a workaround for getting a decent Q estimate.
Here is a totally made up example of what someone may suggest: "R gets quite high at frequencies way higher than those the coil will be used at. At those high R values, the error is less. Take that number, and “everyone knows” equation XYZ for skin effect is quite accurate, so use equation XYZ to back-calculate R at lower, practical frequencies. Now you can estimate Q reasonably well."
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Re: Measuring different results
David Reichard: That's not what I thought about, maybe it's a language barrier issue, I'm using a translator.The SWR meter designed for 50 Ohms is only able to measure SWR for a 50 Ohm antenna system, it cannot measure SWR for a 75 Ohm antenna system. I have redrawn the measurement bridge from NanoVNA to LTspice to easily do sample calculations. The bridge is powered from a V1 source of 1V. The NanoVNA measures the voltage across resistor R9 (I called nodes M1 and M2) Let's calculate the voltage for values 1 50 2500 and their 25% higher values: 1,25 62,5 3125 testval V(M1)-V(M2) 1 -0,3161 1,25 -0,3120 diff -0.0041 50 0,0003 62,5 0,0273 diff -0.0270 2500 0,1937 3125 0,1949 diff -0.0013 As you can see, 0.0270 is 6.6 times larger than 0.0041, and as much as 20.7 times larger than 0.0013. The NanoVNA measures the voltage and calculates the impedance. As you can see, for high impedances such as 2500 ohms, a very small change in voltage corresponds to a very large change in impedance, so that a small error in voltage measurement translates into a large error in impedance. At low impedances there is a similar problem, but not as large. A neighboring thread relating to low impedances: /g/nanovna-users/topic/nanovna_low_z_capabilities/86085049Then there's the cable transformation, which can turn low impedance into high impedance and vice versa. Calibration tries to compensate for this, it is a software action, but the bridge measures what is connected to it, and this error cannot be avoided.
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Re: Measuring different results
Btomek:
I think you are saying "A moderate change in impedance (resistance + reactance) has little effect on thee SWR/reflection coefficient when the SWR is close to 1:1 but a large effect when the SWR is high to start with." Is that about right?
I found this on Wikipedia: "SWR is usually measured using a dedicated instrument called an SWR meter. Since SWR is a measure of the load impedance relative to the characteristic impedance of the transmission line in use (which together determine the reflection coefficient...), a given SWR meter can interpret the impedance it sees in terms of SWR only if it has been designed for that particular characteristic impedance." Just as you stated.
BTW, I seldom contribute to this forum but I read most of the posts and find the discussions quite educational. Thank you all!
- David
Ham KD6DWR/GMRS WQYV533
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of btomek@... Sent: Sunday, October 10, 2021 7:15 AM To: [email protected]Subject: Re: [nanovna-users] Measuring different results The NanoVNA measuring bridge at the S11 connector is in equilibrium at a load of 50 Ohms, and works most accurately in this region. The further away from 50 Ohms the more error there is in the measurement per R and X. The NanoVNA measures the reflection coefficient, and for this 910+j1610 we have SWR=75.21, and for 1580+j1880 SWR = 76.36. This corresponds to a reflection coefficient of 0.9738 and 0.9741. As you can see, the difference is only 0.0003 of the reflection coefficient. For comparison, 46.5+j2.85 = SWR 1.098, 46.2+j2.48 = SWR 1.099. The corresponding reflection coefficients are 0.04671 and 0.04717, a difference of 0.00046. -- This email has been checked for viruses by AVG.
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Re: Measuring different results
Hello,
The calibration is done with the same cable and the same calibration set on both units.
Were you using "the same cal set file" between both units? Seen this before where the new VNA s/w release changed cal data set format thus breaking backward compatibility.? Opps. 73's wb9own
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Roger Need
David Reichard