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Re: Crystal measurements & QEX review
Thanks for the responses.
The absolute accuracy of the frequency source isn't generally much of an issue for me. It does need to be stable during the measurement process though. The formulas used to determine Lm and Cm do take the source and detector resistances into account. It's common to use 12.5 ohms and have either 4:1 transformers on both ends or use minimum loss pads of 50 to 12.5 ohms on both ends, which is what I'm doing. I usually find Rs based on the difference in attenuation with the crystal installed, at resonance, and attenuation with the fixture shorted. I suppose this VNA would give me a direct reading of Rs though ... I should have mentioned that the QEX article was probably pretty out-of-date by publication time, for example the "saver" software wasn't discussed. But it appears that the author's "resolution" issue was not with the precision with which the synthesizer chip is programmed but had more to do with the measurement techniques, which sort of went over my head. I did do a crystal measurement on a similar VNA device at one time and got good agreement with other measurements. The device is described to an extent here, scroll down to product #25: It uses similar hardware to the nanoVNA but what goes on inside its brain (in either case), I don't know. I've generally not found Co to be critical in filter design but it does seem to come into play more when designing voice BW filters. I either use rule-of-thumb values or measure with my AADE type instrument. My belief is that matching frequencies closely is a good technique if you aren't going to measure the crystal parameters, but otherwise it's of lesser importance. Of course if one deviated by a large amount, I wouldn't use it in my filter. 73, Nick, WA5BDU |
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Re: Alibaba ordering
Dr. Dave,
I used to sell on Amazon, it may be a bit different in the UK/Euroland... AND it may be different for different types of products as well. But my product was warehouses by them for free, I sent them 10 units at a time (and depending on the sales volume, would take more at a time). They paid me as they sold OR at my choice with a very slightly discounted rate, monthly. You are correct, in the US Amazon is GREATLY trusted over Ebay, Alibaba (and other Chinese sites are at the bottom of the list for good reason!). Very few if anybody in the US do "Bank Transfers" to anybody for online products. That is a HUGE NO NO! Paypal is very well trusted. The problem with ebay is, you never know what you will get or who you are dealing with. Perfect example, I bought my Nanovna on ebay, pictured was the correct unit (the -H and good one, although not the new PCB version, but I was ok with that). The add stated it shipped from the US, and it looked like a US add. What arrived was the bad unit with the missing "Ch0" text, and it arrived from Hong Kong via DHL in 2 weeks instead of 1 or 2 days as is custom in the US. I had to fight with the ebay seller to get a refund, and they then of course said just keep the unit because they did not want to pay return shipping to Hong Kong. So I ended up with a "free" bad vna. I have since ordered the real deal from Alibaba BUT direct via paypal. Still waiting on unit. Amazon would have been easier for everyone involved. ;-) -- Regards, Chris |
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Re: Alibaba ordering
I need to get with him, My time machine only goes forward.. After work on Friday, I jump in it to get the Saturday night lottery numbers in Sunday morning's paper... That's when I found-- NO REVERSE.. Can't go back to buy a ticket with the winning numbers, nor go out to the dance hall on Saturday night..
Further, found I have to go back to work on Monday Morning, No weekend, No Dance Hall, No winning Lottery Numbers.. Don't waste your time on a Time Machine unless it goes Forward and Reverse... |
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Re: NanoVNA-saver and Windows XP
Hi Alberto, I use NANOVNA_SAVER 0.2.1 om my old PC where Win-Xp (S.P.3) is running ...
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No problem at all ! Perhapsthis is due to the fact the mine is equiped by INTEL CPU (P4) ... and, as far as I know, AMD PROCESSORS cannot handle all Ham S.W. Let's wait for the author's answer ... 73 Peter I0YLI ----- Original Message -----
From: "Alberto I2PHD" <i2phd@...> To: <[email protected]> Sent: Friday, January 03, 2020 8:37 PM Subject: [nanovna-users] NanoVNA-saver and Windows XP I know, I know, no need to say it again... Windows XP is dead, it is no more maintained, etc. etc. But there are still a lot of XP installations out there, sufficiently protected from the malware (like mine)... I have three towers, Windows 7, Windows 10 and the one I am using for ham-related stuff, with Windows XP. It cannot be upgraded, not even to Windows 7, as its Athlon CPU lacks some features Microsoft deems absolutely necessary for Windows 7 and 10. Said that, I tried to download and run the program nanovna-saver-v0.2.1 on this PC. I was greeted with a message saying that in the kernel32.dll the entry point GetFinalPathNameByHandleW could not be located... And actually that API is missing from that DLL.... I am asking here if the author(s) if the nanovna-saver program could make it runnable also under Windows XP. Thanks, Alberto |
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NanoVNA-saver and Windows XP
I know, I know, no need to say it again... Windows XP is dead, it is no more maintained, etc. etc.
But there are still a lot of XP installations out there, sufficiently protected from the malware (like mine)... I have three towers, Windows 7, Windows 10 and the one I am using for ham-related stuff, with Windows XP. It cannot be upgraded, not even to Windows 7, as its Athlon CPU lacks some features Microsoft deems absolutely necessary for Windows 7 and 10. Said that, I tried to download and run the program nanovna-saver-v0.2.1 on this PC. I was greeted with a message saying that in the kernel32.dll the entry point GetFinalPathNameByHandleW could not be located... And actually that API is missing from that DLL.... I am asking here if the author(s) if the nanovna-saver program could make it runnable also under Windows XP. Thanks, Alberto |
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Re: Updating the firmware
Ciao Alberto,Ciao Lucio e grazie. Ho visto il pointer a quel PDF nel Wiki, e questo mi ha permesso di aggiornare il nanetto... Grazie ancora e Buon Anno ! 73 Alberto I2PHD |
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Re: Updating the firmware
========================
Forget it. I found the relevant info on the Wiki section of the group. Firmware updated successfully. And, thanks God, despite being 75, I can still clearly and effortlessly read the crispy 2.8" LCD screen of the unit. When the hugen's bigger screen model will be out, probably I will buy it, but the current one is manageable. |
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Re: errors of "error" models
#103 : The Fourth Load *
Dear all, Yes, indeed ! - - - - - - - - - - - - - (c) gin&pez@arg (cc-by-4.0) 2019 : start - - - - - - - - - - - It seems that the ratio of these two cross-ratios, the one of the loads and the other one of their corresponding measurements, is equal to the constant (1,0). But in fact, the origins of these two cross ratios are obviously different for The Common User, who connects exterior loads to his VNA to get the corresponding interior measurements from it - that is very different, indeed. The trick, that convinces The Common User (who is an unsuspected one, an innocent enough), has to do with two imperceptible leaps, from practice to theory and then back to practice again, as follows: (1) In Practice : The Common User (who is an unsuspected one, an innocent enough), connects 3 loads, which he believes, instead of he prays-hopes-thinks but finally just * l i k e s *, that are of a well defined known value (and perhaps of uncertainty), that is a so called a standard one : S, L, O, as well as, he also connects The Fourth Load, an unknown one, so that his VNA shows to him their corresponding four 4 measurements : s, l, o, g, which in this way are all * i n d e e d * known, then (2) In Theory : The corresponding value of The Fourth Load, that is the one which The Common User (who is an unsuspected one, an innocent enough), he * l i k e s * to consider it as the only one unknown, is * c o m p u t e d *, either by his VNA itself or by his one hand, by using the * t h e o r e t i c a l * a b s o l u t e * equality of this ratio of these two cross-ratios (but of their very different origins, the one from the loads and the other one from their corresponding measurements) to the constant (1,0), and finally again (3) Back in Practice : It is exactly this * t h e o r e t i c a l * value of The Fourth Load, that The Common User (who is an unsuspected one, an innocent enough), he * l i k e s * to take it for granted. - - - - - - - - - - - - - finish : (c) gin&pez@arg (cc-by-4.0) 2019 - - - - - - - - - - - Sincerely, gin&pez@arg * #102: The Complete "Demystification" of the "VNA Measurements" Kind - Farewell /g/nanovna-users/message/9073 :103# |
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Re: NanoVNA Presentation
#measurement
#nanovna-saver
#tutorials
Hi Luc,
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Thanks for your great work ! Enrique lu8eff El vie., 3 de ene. de 2020 a la(s) 13:31, Luc ON7DQ (on7dq@...) ±ð²õ³¦°ù¾±²ú¾±¨®: Hi Folks, |
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Re: Calibration standards
Hi Ed
I can only say very soon ? I do not know exactly when. I will hint you. Else it will be announced on the VNWA.io group. The link is /g/vnwa Hind regards Kurt -----Oprindelig meddelelse----- Fra: [email protected] <[email protected]> P? vegne af Ed Jones Sendt: 3. januar 2020 14:54 Til: [email protected] Emne: Re: [nanovna-users] Calibration standards On Thu, Jan 2, 2020 at 10:12 AM, Kurt Poulsen wrote: Thanks for the information, Kurt. Those seem like a practical, less expensive way to get some decent calibration standards. As I have poked around the Wiki and the links you posted, I now realize you have spent a lot of time documenting these standards. Thank you for that! Do you know when the N-calibration kit will be available from SDR-Kits? -- Ed Jones - K8MEJ - Lewis Center, Ohio U.S.A |
Nick Kennedy
Chris K2STP
Larry Macionski
Peter
Alberto I2PHD
gin&pez@arg
Enrique A. Wembagher LU8EFF
John
Kurt Poulsen