Re: Inductor Q Measurement
Yes, R cannot be < 0, but my interpretation is simply that the -2 is error in some small number like, say 1 or 2 ohms. I will admit that many of you experts talk about how you attach your DUT very carefully, solder it, sometimes have to throw it away when done testing, and all this sounds bizarre to a non-EE who is simply playing with crystal radio. My nanoVNA attaches to my DUT via 2 alligator clips which are on little connectors (BNC maybe?) which screw into the VNA. I recognize that I am accepting error, even though I do my calibration at the same alligator clips, but except for R, I am convinced that the error I am accepting is negligible when my interest is 0.5 to 25 MHz, picking up AM signals. (I welcome any insights if you think I am wrong.)
Andy
toggle quoted message
Show quoted text
On Oct 12, 2021, at 10:05 AM, Jim Lux <jim@...> wrote:
On 10/12/21 6:05 AM, DougVL wrote:
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. Depending on how the conversion from reflection or transmission coefficient (gamma) to R+jX is done, a coefficient with magnitude >1 will result in negative R.
If you're measuring low impedances (so |gamma| is close to 1) then noise or roundoff errors in a measurement can wind up with gamma>1
|
suitable software to control full funcion NanoVNA
Hello, there is one suitable PC software to control the full function of NanoVNA for windows?
73/Francesco
|
Re: Inductor Q Measurement
Bill, I'm not sure this does what you want, but try it: Set frequency, coil diameter, and wire gauge. Click on Turns for turns/inch and set the value you have in mind. Then vary coil length with the mouse wheel until you get the desired inductance. It's really fast if it's what you need. The only thing I truly automated was Q optimization.
Brian
|
Re: Inductor Q Measurement
Gary,
Have you evaluated the Q at OR near the SRF and then the Q significantly below SRF?
|
It's not the backlight current as it runs off the 5v line, not the 5V-RF or the 3V sources.
Since the unit is new, it's most likely infant-mortality on the part or a counterfeit part was used that was mislabelled as a higher current device when in fact it wasn't. Lots of that in China, unfortunately.
Yes - claim a replacement. If they tell you to keep the old one, you can source 3V LDO devices from old scrap home wifi routers and access points as they all use 3v parts.
toggle quoted message
Show quoted text
On Tuesday, October 12, 2021, 12:43:55 p.m. EDT, cube1us <cube1@...> wrote: As a guess, a thermal issue? 73 JRJ? WIYN On 10/12/2021 7:33 AM, Jens M?ller 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
|
Re: Inductor Q Measurement
Hi Brian,
Thanks for reminding all about COIL. It takes a little getting familiar with it since you use an interesting GUI interface, but I got the handle on it.?
Is there a way to input the coil inductance, fix the physical parameters and come up with the required turns. It didn't seem like it. It's still very useful - thanks again.
Regards...Bill - N6GHz
toggle quoted message
Show quoted text
On 10/12/2021 05:47:39, Brian Beezley <k6sti@...> wrote:
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
|
As a guess, a thermal issue?
73 JRJ WIYN
toggle quoted message
Show quoted text
On 10/12/2021 7:33 AM, Jens M?ller 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
|
Thanks,
It looks like the LD01 is defective as only 1V is coming out instead of 3V.
I didn't expect to have a defective unit as I posses it only 2 weeks.
I'll claim for a replacement rather than chaning the regulator.
Anyhow thanks for help.
Am 12.10.2021 um 16:10 schrieb Larry Rothman:
toggle quoted message
Show quoted text
Well, it appears you have some type of hardware failure..
if you reconnect the battery, measure the voltage at the power SW with the USB cable disconnected - it should be 5V.
Turn ON and? measure the voltage at the 3V LDO1 regulator in and out (see schematic image). In=5V, VDD out =3V (at edge of PCB beside the Boot-0 pin)
Measure 5V out of IC 3
Refer to the photo of the H4 board here:
/g/nanovna-users/photo/0/34671.24755.1?p=Created%2C%2C%2C20%2C2%2C20%2C0
It's really just standard troubleshooting at this point, unfortunately.
BTW - when you turn the unit ON and it is disconnected from USB, is the LED flashing?
On Tuesday, October 12, 2021, 09:48:42 a.m. EDT, Jens M?ller <df9hj@...> wrote:
Disconnected battery still doesn't power up at usb only.
Am 12.10.2021 um 15:11 schrieb Larry Rothman:
? 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
|
Re: Inductor Q Measurement
Quick and dirty method... Just measure the self resonance of your coil. If you calibrate the nVNA to your fixture and then just run the S11 sweep up high enough on the coil, you will undoubtedly see a resonant peak. At low frequency you can determine the inductor, L. (the nVNA saver software will do this for you) The frequency of the peak tells you the self resonant parasitic capacitance, C. From the magnitude of the the resistance, R, measured at self resonance, and the calculated self resonant impedance, Z=sqrt(L/C), then Q will be R/Z.
This procedure also shows you explicitly when parasitic capacitance becomes important -- which it often does!
|
Re: Inductor Q Measurement
Brian, thanks for the background information on COIL I have gotten many
features to work under Wine in Linux and it is very useful. I may have
spoken a bit too soon in implying everything would work with Wine. However,
I need to brush up on Wine and to try COILS on a Windows machine to see
what I may be missing. Thanks again!
Dave
toggle quoted message
Show quoted text
On Tue, Oct 12, 2021 at 8:47 AM Brian Beezley <k6sti@...> wrote: 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
|
Well, it appears you have some type of hardware failure.. if you reconnect the battery, measure the voltage at the power SW with the USB cable disconnected - it should be 5V. Turn ON and? measure the voltage at the 3V LDO1 regulator in and out (see schematic image). In=5V, VDD out =3V (at edge of PCB beside the Boot-0 pin) Measure 5V out of IC 3 Refer to the photo of the H4 board here: /g/nanovna-users/photo/0/34671.24755.1?p=Created%2C%2C%2C20%2C2%2C20%2C0It's really just standard troubleshooting at this point, unfortunately. BTW - when you turn the unit ON and it is disconnected from USB, is the LED flashing?
On Tuesday, October 12, 2021, 09:48:42 a.m. EDT, Jens M?ller <df9hj@...> wrote: Disconnected battery still doesn't power up at usb only. Am 12.10.2021 um 15:11 schrieb Larry Rothman: ? 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
? ? ?
? ?
|
Re: Inductor Q Measurement
On 10/12/21 6:05 AM, DougVL wrote: 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. Depending on how the conversion from reflection or transmission coefficient (gamma) to R+jX is done, a coefficient with magnitude >1 will result in negative R. If you're measuring low impedances (so |gamma| is close to 1) then noise or roundoff errors in a measurement can wind up with gamma>1
|
Disconnected battery still doesn't power up at usb only.
Am 12.10.2021 um 15:11 schrieb Larry Rothman:
toggle quoted message
Show quoted text
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
|
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.
toggle quoted message
Show quoted text
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
? ?
|
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
|
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
|
Hello Larry,
Thank you for your reply.
No that doesn't help.
Am 12.10.2021 um 13:47 schrieb Larry Rothman:
toggle quoted message
Show quoted text
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
toggle quoted message
Show quoted text
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
|
Francesco
cube1us
