On Mon, Oct 10, 2022 at 07:09 AM, Charlie Thompson wrote:
My observation/experience with inductors that large (~240uH) at those
frequencies is caused by two effects: 1) skin effect 2) proximity effect. The
latter being less known about yet a significant contributor to resistive
losses in the inductor. I suspect you will find the capacitor resistive losses
are *lower* than the inductor¡¯s resistive losses. How did you calculate the
1.5 ohms for the inductor?
Yes, the capacitor loses will be much less than the inductor. A very good air cap can have Qs from 8,000 to 20,000. A really good Q for an inductor is 1400, but some have built BCB inductors near 2000, using 1162/46 litz wire. Proximity effect was the reason I did the 5 coil experiment to find the optimum spacing for 660/43 litz. I measured Q on my Boonton 260A* and R(loss) = XL/Q, the 1.5¦¸ was a guestimate using, XL @1MHz = 1508¦¸, Q =1000 R = 1.508¦¸. Real measurements, looking at my graphs, best case, XL @ 800kHz = 1,191¦¸, Q = 1440, R = 0.827¦¸. I see R(loss) of 0.577¦¸ at 500kHz for the 12 Turns per inch coil. The worst case of my 5 coils, has over 3¦¸ R(loss) at 1700kHz. I expect Capacitor R(loss) under 0.2¦¸. I still need the math for extrapolation if anyone can help. * also did 3db Q test to verify. Thanks, Mikek P.S. My graphs were an average of 4 measurements at each frequency.
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My observation/experience with inductors that large (~240uH) at those frequencies is caused by two effects: 1) skin effect 2) proximity effect. The latter being less known about yet a significant contributor to resistive losses in the inductor. I suspect you will find the capacitor resistive losses are *lower* than the inductor¡¯s resistive losses. How did you calculate the 1.5 ohms for the inductor?
-Charlie
W5CDT
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On Mon, Oct 10, 2022 at 12:20 AM, tuckvk3cca wrote:
If you use a resonant circuit to find the Q, the loss with be combination of
both the L and C. You can only separate it if you can independently measure
the loss of the coil or capacitor without the resonance.
That is why I have the question, from my quick reading of the paper, it seemed like the author separated them, but I agree with you, at resonance you can't separate them. Alternatively I would parallel the capacitor with a series of high value resistors R. Measure the Z. Then extrapolate to zero R to find residual R in Z. By extrapolate to zero, here is about as far as I understand that concept, my example would be finding the output impedance of an amp by taking two measurements with two different value of resistor and extrapolate to find the output impedance. I expect values under 0.2¦¸ and hopefully less if I have any good air caps. Is there a math expression that you can tell me to do the extrapolation? I don't have the math skills to figure that out. If have that, I can take many measurements over frequency, plug everything into Excel and make graphs of my better capacitors. Thanks, Mikek
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If you use a resonant circuit to find the Q the loss with be combination of both the L and C. You can only separate it if you can independently measure the loss of the coil or capacitor without the resonance. For low frequencies you can use an ESR meter to measure the loss if the capacitor. Alternatively I would parallel the capacitor with a series of high value resistors R. Measure the Z. Then extrapolate to zero R to find residual R in Z. This method can be used at any frequency.
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The NanoVNA-H suddenly has a white screen. I am able to use a PC and it seems to be working. This afternoon was going to see if I could work my way thru the problem and the battery was dead. After connecting the usb the screen came up and was normal. left the unit connected so the battery would charge and now I am back to a white screen. Any ideas on what the next step needs to be?
Thanks
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On Sun, Oct 9, 2022 at 01:05 PM, Roger Need wrote:
What type of 240 uH inductor will you be using to get such a low R over that
frequency range?
Well, it won't be that low over the whole range. But I have coils that reach 1400Q of the top of my head. I'll post a picture and some graphs of measurements made. Mikek
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On Sun, Oct 9, 2022 at 12:54 PM, Mikek wrote: 2) I want to test an air capacitor, at several points from 20pf to 400pf over
a frequency range of 500kHz to 1700kHz, probable requiring a 240uh inductor.
That 240uh inductor will have about 1.5¦¸ of loss and more over that
frequency. What type of 240 uH inductor will you be using to get such a low R over that frequency range? Roger
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Hi all,
On another group there is a discussion on Q meters, then we went to the loss the air cap added to the loss of the inductor during measurement.
So all we know is the combined loss not the individual losses.
This article purports to measure with a VNA capacitor losses.
But,
1) I can't see how the author separates the inductor and capacitor losses, as he does use a coil to resonate.
2) I want to test an air capacitor, at several points from 20pf to 400pf over a frequency range of 500kHz to 1700kHz, probable requiring a 240uh inductor.
That 240uh inductor will have about 1.5¦¸ of loss and more over that frequency. I don't see measuring 0.1¦¸ and 0.2¦¸ capacitor losses if the coil losses aren't separated.
Can you get my thinking straightened out?
Mikek
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SAA2-N device driver on Win 7
When I plug unit in, device manager says it's a CDC-ACM Demo device. Does not appear under Ports (COM &LPT)
What is the problem?
Works ok under win 10 as a usb extensible host controller and QT software recognize it as port COM 5
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I should suspect that with a techinically savy group, someone would have pointed out that the it is easy to spoof the origin of an email and just because a piece of spam says it is from a source is no indication that it is so. I have not seen any such claiming to be from groups.io. Now on the other hand I actually got a piece of unsolicited mail from the Epoch TImes in my postal mail box. It was a newspaper.
73 to all
Jim
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More likely that someone put your name on a list. Check with your
conservative anti-Chinese friends. I am sure you probably have at least
one closeted one.
Jim Barber
*N7FZ*
Phone: 503.547.9524
<>
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On Sat, Oct 8, 2022 at 3:29 AM Dave Daniel <kc0wjn@...> wrote: Is anyone besides myself receiving periodic spam from theepochtimes.com?
I'm trying to figure out if this is a group spam problem or a personal
spam problem.
DaveD, co-owner
--
This email has been checked for viruses by Avast antivirus software.
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On 09/10/2022 00:25, Dennis Finegan wrote: I have not received any spam from Groups.io and I subscribe to several.
Same here in Edinburgh. David -- SatSignal Software - Quality software for you Web: Email: david-taylor@... Twitter: @gm8arv
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I have not received any spam from Groups.io and I subscribe to several.
Dennis
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Still nothing seen here.
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On October 8, 2022 3:14:17 PM CDT, Dave Daniel <kc0wjn@...> wrote: Ok, I was apparently not clear in my earlier email, so I am going to rephrase the question:
Is anybody besides me receiving email from theepochtimes.com as posts to the nanovna-users group (e.g., received as sent to the [email protected] email address and not solely to one's personal email address). I am not chasing email received on your personal account, only postings to the group.
As to those who objected to my earlier enquiry, the purpose of the enquiry was, and is, to try and understand whether or not there is a threat to the group. I take dealing with threats to the group very seriously. Occasionally this means that some of the group's bandwidth must be used to poll the group in order for me to understand what the group members are seeing. If you don't like that, feel free to use the delete facility on your computer and absolutely feel free to leave the group, but *do not complain* when I create a post that has to do with the security and/or viability of the group. Doing so will get you moderated or banned. 'Nuff said, I think.
We don't need to spend any time with discussion between members about The Epoch Times on the group. I just want to know if The Epoch Times is intruding into the group and, if so, to what extent and what, if any, action needs to be taken by the co-owners to deal with that. In point of fact, had I asked the correct question in the first place and received useful answers, I had planned to freeze the thread anyway.
Thank you.
DaveD
On 10/8/2022 6:29 AM, Dave Daniel wrote:
Is anyone besides myself receiving periodic spam from theepochtimes.com? I'm trying to figure out if this is a group spam problem or a personal spam problem.
DaveD, co-owner
--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
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Sent from my Android device with K-9 Mail. Please excuse my brevity.
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If we still have a NARRATOR out there I'd suggest he 'nip these idiots' NOW before we loose our REAL nanovna group.
Mike C.
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On 10/8/2022 7:09 AM, Gary - W6GVS wrote: I received an unsolicited copy of Epoch Times (a.k.a. Trump's Times) in the snail mail about a month ago.? It was very useful as a wastebasket liner.
73,
Gary - W6GVS
At 06:29 AM 10/8/2022, you wrote:
Is anyone besides myself receiving periodic spam from theepochtimes.com? I'm trying to figure out if this is a group spam problem or a personal spam problem.
DaveD, co-owner
--
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I am not sure that political comments are germane to the use of the nanovna.
Last checked the measurements did not sem to care which party you belonged
to.
So maybe back on topic?
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On Sat, Oct 8, 2022 at 4:57 PM Mike C. <mg@...> wrote: I guess you don't approve of TRUTH???
Mike C.
On 10/8/2022 6:55 AM, Douglas Butler wrote:
I have recently been getting a lot of Epoch Times (a political slant I loathe) ads in my web browser, but not by email. I suspect ET is just
running a major advertising blitz in the run-up to the election that is
unrelated to this group.
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73,
AB1PH
Don Rolph
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I guess you don't approve of TRUTH???
Mike C.
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On 10/8/2022 6:55 AM, Douglas Butler wrote: I have recently been getting a lot of Epoch Times (a political slant I loathe) ads in my web browser, but not by email. I suspect ET is just running a major advertising blitz in the run-up to the election that is unrelated to this group.
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No, I am not. 73 -Jim NU0C On Sat, 8 Oct 2022 16:14:17 -0400 "Dave Daniel" <kc0wjn@...> wrote: Is anybody besides me receiving email from theepochtimes.com as posts to
the nanovna-users group (e.g., received as sent to the
[email protected] email address and not solely to one's personal
email address). I am not chasing email received on your personal
account, only postings to the group.
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If you got one of those what happens when you click on the "View/Reply Online" ?
I don't see any such messages in the group message history.
Mike W9MDB
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On Saturday, October 8, 2022 at 03:14:30 PM CDT, Dave Daniel <kc0wjn@...> wrote: Ok, I was apparently not clear in my earlier email, so I am going to rephrase the question: Is anybody besides me receiving email from theepochtimes.com as posts to the nanovna-users group (e.g., received as sent to the [email protected] email address and not solely to one's personal email address). I am not chasing email received on your personal account, only postings to the group. As to those who objected to my earlier enquiry, the purpose of the enquiry was, and is, to try and understand whether or not there is a threat to the group. I take dealing with threats to the group very seriously. Occasionally this means that some of the group's bandwidth must be used to poll the group in order for me to understand what the group members are seeing. If you don't like that, feel free to use the delete facility on your computer and absolutely feel free to leave the group, but *do not complain* when I create a post that has to do with the security and/or viability of the group. Doing so will get you moderated or banned. 'Nuff said, I think. We don't need to spend any time with discussion between members about The Epoch Times on the group. I just want to know if The Epoch Times is intruding into the group and, if so, to what extent and what, if any, action needs to be taken by the co-owners to deal with that. In point of fact, had I asked the correct question in the first place and received useful answers, I had planned to freeze the thread anyway. Thank you. DaveD On 10/8/2022 6:29 AM, Dave Daniel wrote: Is anyone besides myself receiving periodic spam from
theepochtimes.com? I'm trying to figure out if this is a group spam
problem or a personal spam problem.
DaveD, co-owner -- This email has been checked for viruses by Avast antivirus software. www.avast.com
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Ok, I was apparently not clear in my earlier email, so I am going to rephrase the question: Is anybody besides me receiving email from theepochtimes.com as posts to the nanovna-users group (e.g., received as sent to the [email protected] email address and not solely to one's personal email address). I am not chasing email received on your personal account, only postings to the group. As to those who objected to my earlier enquiry, the purpose of the enquiry was, and is, to try and understand whether or not there is a threat to the group. I take dealing with threats to the group very seriously. Occasionally this means that some of the group's bandwidth must be used to poll the group in order for me to understand what the group members are seeing. If you don't like that, feel free to use the delete facility on your computer and absolutely feel free to leave the group, but *do not complain* when I create a post that has to do with the security and/or viability of the group. Doing so will get you moderated or banned. 'Nuff said, I think. We don't need to spend any time with discussion between members about The Epoch Times on the group. I just want to know if The Epoch Times is intruding into the group and, if so, to what extent and what, if any, action needs to be taken by the co-owners to deal with that. In point of fact, had I asked the correct question in the first place and received useful answers, I had planned to freeze the thread anyway. Thank you. DaveD
On 10/8/2022 6:29 AM, Dave Daniel wrote: Is anyone besides myself receiving periodic spam from theepochtimes.com? I'm trying to figure out if this is a group spam problem or a personal spam problem.
DaveD, co-owner
--
This email has been checked for viruses by Avast antivirus software.
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F4WCV
Roger Need
David J Taylor
Mike C.
Jim Shorney