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Re: Measuring impedance at the bottom end of a ladder-line-center-fed wire dipole
How do you normally operate the ladder line?
Using a balun or via an antenna tuner that provides balanced output? In case you use a balun simply connect the nanoVNA to the balun and measure. When using an antenna tuner disable all "tuning" and use the tuner as a pure balun. Without a balun (in case your receiver has something buildin) your proposed approach will work but be aware the ladder line impedance is high compare to 50ohm -- NanoVNA Wiki: /g/nanovna-users/wiki/home NanoVNA Files: /g/nanovna-users/files Erik, PD0EK |
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Re: On Line, Secure, Transactions
On 2019-12-28 9:59, Dana Whitlow wrote:
Some things to consider about online purchases:The technique I use is a bit different. The credit card offered by my bank has a special function, that allows to generate a one-use-only credit card number, meaning that after that number has been used once, is no more valid... additionally, you can specify the maximum amount that CC number can be charged from. So, when buying online from a vendor that does not accept Paypal, I generate such a CC number, specifying a max amount just slightly larger than the cost of the item, and send it. This way I am sure the vendor cannot reuse that CC number or charge me a large amount of money.... -- /*73 Alberto I2PHD* <<< >>>/ |
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Measuring impedance at the bottom end of a ladder-line-center-fed wire dipole
How would you do it?
I'm thinking that first, I'd need to construct an adapter for the VNA - sma connector, short length of coax, with clips on the center conductor and shield to clip to the two sides of the ladder line (but, the quality of the connection between the clips and the ladder line wires (among other things) is going to introduce variables, right?) Second, I should calibrate for the desired frequency range using the adapter as described above, in order to "calibrate out" as much of the peculiarities of the measurement system as I can - I would clip my adapter to my QRP-Labs dummy load for the load part, leave the clips dangling for the open, and clip them together for the through. What kind of trouble am I going to be getting myself into? |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
GmailK4KV
Herb,
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Thanks for the information.? Obviously, I am new here, and do not own a unit yet.? I have a N2PK VNA, that has now started to act up.? It is pretty much a laboratory piece of equipment, comparing very favorably with the HP unit. But now it is sick, and was limited to 60Mhz. So, now am going to buy the nano, but want a bigger screen.? My N2PK VNA is just a black box with which you MUST have a PC.? Having a link to pc software is essential when doing circuit development.? One has to compare the old scan with the latest one. One comment I will make, and not to upset anyone, but there seemed to be a fixation on cost.? Take my viewpoint: I spent $600 building my N2PK VNA, so getting a really great nano at, say, at $125 is no big deal.? Bigger screen, Ghz oscillator, beefier connectors is all good! 73 Glen K4KV On 12/28/2019 07:31, hwalker wrote:
On Sat, Dec 28, 2019 at 03:55 AM, GmailK4KV wrote: |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
On Sat, Dec 28, 2019 at 03:55 AM, GmailK4KV wrote:
I do this kind of stuff too, and get NO help ;-) being a "one-man" show. I have to do the hardware AND software. ======================================================================================= Glen, hugen pretty much has been where you are except he was able to piggyback his efforts on edy555's prior design. His original NanoVNA-sharp software was barebones, but demonstrated the solid communications api of edy555's original firmware. Additional support that hugen has received from the community has been because of the true open source nature of The NanoVNA design. Everything from source code to schematics is readily available on GitHub. I admire that hugen hasn't rested on his laurels but continues to innovate and contribute to the general NanoVNA community. - Herb |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
On Fri, Dec 27, 2019 at 11:44 PM, <hugen@...> wrote:
"...I will print the NanoVNA-H label and the hardware version number on the PCB I sell, and there will be a QR code next to the screen of the main pcb for accessing nanovna.com." ================================================================= hugen, May I also suggest that the label that you now attach to the back of the NanoVNA-H case include the PCB version number. That information is currently not accessible without taking apart the case. Congrats to all who contributed to the development of the NanoVNA-H 4. Especially proud that some members of this group contributed. - Herb |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
GmailK4KV
Oh, I forgot to mention, thanks very much to the developers for all their hard work.? I do this kind
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of stuff too, and get NO help ;-) being a "one-man" show.? I have to do the hardware AND software. 73 Glen K4KV On 12/28/2019 06:35, GmailK4KV via Groups.Io wrote:
I have used the high performance ARM32 chip on the Teensy 3.2. 120Mhz processor, huge memory, big pin |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
I have used the high performance ARM32 chip on the Teensy 3.2. 120Mhz processor, huge memory, big pin
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count.? I run a 3.6" color touch screen on my projects.? It would handle this stuff with ease. 73 Glen K4KV On 12/28/2019 01:26, hugen@... wrote:
Thanks to the work of AA6KL, almost all the functions now work well. |
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Re: On Line, Secure, Transactions
Some things to consider about online purchases:
1. Your special debit account presumably still links back to your SSN. Remember, you had to give your SSN when opening that account, so there is a link. 2. Your credit rating is still at risk. If a fraudulent purchase is made online, it's commonly the merchant who ends up holding the bag (not the CC company), and he/she is always free to file adverse reports to the credit reporting agencies etc. Item two was initially gleaned from an evening seminar on ID theft given by my bank, then years later "confirmed" by research on the web. I've mentioned this to personnel at another bank at which I've done most business recently, and the response was "Oh, that could not possibly be true, but we'll check into it for you." I've never received any further response on that, so I feel that prudence dictates assuming the worst. My online purchases are only from organization(s) who accept payment by gift card, specifically a gift card that can be purchased anonymously with cash. Unfortunately there is only one such vendor (of which I'm aware) that sells anything in which I'm interested. Mostly I purchase by voice telephone and prefer to make payment by cashier's check, whose link to my personal info is probably about as tenuous as can be managed. Dana |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
Sorry, it's hard for me to judge because there are many clones now. If the version you buy works well, you don't have to worry too much. Thanks to the good design of nanovna, the manufacturer can easily make a usable version, but there will be some differences at higher frequencies. The version I sell will include good shielding and guarantee good isolation. Some clones may also be shielded, but they may cause poor isolation due to their incorrect installation. And I will print the NanoVNA-H label and the hardware version number on the PCB I sell, and there will be a QR code next to the screen of the main pcb for accessing nanovna.com.
hugen |
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Re: New NanoVNA-H just received
Thank you for your support. Since some European countries charge high tariffs on DHL, we provide postal express. If you buy from Maggie through Alibaba, NanoVNA-H Rev3.4 will be shipped now. If you bought from ebay or Amazon, you can ask the dealer for the hardware version, we have now pasted "HW version: 3.4" on NanoVNA-H rev3.4.
Thanks to the work of AA6KL£¬the 4-inch version of NanoVNA-H is coming soon. Like NanoVNA-H Rev3.4, it can work well up to 1.5GHz. /g/nanovna-users/message/8708 hugen |
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Re: Brief NanoVNA-H vs NanoVNA_F comparison
#nanovna-f
Thanks to the work of AA6KL£¬the 4-inch version of NanoVNA-H is coming soon. Like NanoVNA-H Rev3.4, it can work well up to 1.5GHz.
/g/nanovna-users/message/8708 hugen |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
Thanks to the work of AA6KL, almost all the functions now work well.
Due to the use of a Cortex M4 MCU and a 4-inch LCD screen, it is temporarily called NanoVNA-H 4, but this is not the next-generation NanoVNA. It is highly compatible with the NanoVNA-H currently sold. All software developed for NanoVNA can be used directly, except for You only need to modify the data length of the screenshot function. Edy555 is developing the next-generation NanoVNA with high performance, but it takes quite a long time to complete the development. hugen |
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On Line, Secure, Transactions
A suggestion, everybody. Tell the bank that that is to be a /debit card account/ and that itGo to your bank and open another "chequing", er, "checking" account. is/not to be linked to your other accounts/. That is quite easily done. your "real" accounts. Thereafter use that account's card for all yourThen transfer, say, $500 into that debit card account from one of larger everyday transactions. That is to say paying for the lunch with the boys when it's your turn, buying a pair of better quality shoes and...purchasing on line. Register that card as your card on PayPal, Amazon and Aliexpress. is completely separate from your other accounts (different card number,Since there is never any more than $500 in the account and since it different password and different p.i.n. and no link to other accounts), if somebody gets into that account, your maximum exposure is very small even if you lose the argument over security with the bank. It is important to get through the mind of the bank employee setting up the account that your other accounts cannot be accessed or even seen from that account. Check that by going to the bank's automated teller right away and using your new debit card. You must not be able to get at or even see your other accounts. using your p.i.n. will see the $500 balance or whatever the existingSomebody putting an exact clone of that card into a cash machine and balance is and nothing more. He has no knowledge of the other, the "real", accounts. He can't get at you. A dishonest retailer on line or his employee or a confederate to whom he has sold your data cannot bill you for thousands of dollars. years now. The card is registered on Amazon, PayPal and Aliexpress andThat has been done here. The account has been in use for a couple of works with no issues. The idea has worked perfectly. Larger grocery bills, restaurants (a prime location for "card scanning") and all on line purchases go through that account. The card saves depleting out of pocket cash, too, so you don't have to go around town with any more than a few dollars on you. Now and then, as required, the bank branch is dropped into and, say, two hundred dollars is transferred into that every day "working" debit card account to top it up. The only way money can be moved into that account is by a teller in a branch of your bank. She is also the only one who can see all your accounts. When you move money into the account she can also see your face and see your signature on her monitor for comparison. +++++ On 2019-12-27 6:29 p.m., BruceN wrote: On Fri, Dec 27, 2019 at 05:40 PM, hwalker wrote:--I haven't ordered from Alibaba because, like you, I would rather use PayPalI didn't mind using the credit card. It's pretty protected. And I've seen unbranded clones going for $60 on Ebay. You can get it from Hugen for $50 via slow boat from China. Still need to use a credit card though. May everybody have a happy and prosperous new year! John at radio station VE7AOV |
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Re: New NanoVNA-H just received
On Fri, Dec 27, 2019 at 05:40 PM, hwalker wrote:
I didn't mind using the credit card. It's pretty protected. And I've seen unbranded clones going for $60 on Ebay. You can get it from Hugen for $50 via slow boat from China. Still need to use a credit card though. BruceN -- *"To invent, you need a good imagination and a pile of junk"* -- Thomas Alva Edison (1847-1931) |
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Re: New NanoVNA-H just received
Herb, thank you very much for the link info!
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Roy WA0YMH On Fri, Dec 27, 2019, 4:40 PM hwalker <herbwalker2476@...> wrote:
On Fri, Dec 27, 2019 at 02:32 PM, Roy Appleton wrote:to |
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Re: New NanoVNA-H just received
On Fri, Dec 27, 2019 at 02:32 PM, Roy Appleton wrote:
=================================================== Roy, In case you missed it reference message #8700" " ... hugen's official store is: . Ordering from that store is pretty much the only way you can ensure your NanoVNA-H has the version 3.4 PCB installed unless your third party seller is technically savvy or willing to open the case and check (doubtful). I haven't ordered from Alibaba because, like you, I would rather use PayPal than give out my credit card. I also don't like the added postal charges for expedient delivery. In some cases, there is even an unexpected sales tax added to the charge. You can chat with Maggie King at the Alibaba link I referenced earlier and ask if she can recommend a third party supplier of ver 3.4 NanoVNA-H's on eBay. .." - Herb |
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Re: New NanoVNA-H just received
So is the 3.4 version currently available the order and what is the link to
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Alibaba? Roy WA0YMH On Fri, Dec 27, 2019, 4:29 PM hwalker <herbwalker2476@...> wrote:
On Fri, Dec 27, 2019 at 01:44 PM, David Eckhardt wrote: |
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Re: New NanoVNA-H just received
On Fri, Dec 27, 2019 at 01:44 PM, David Eckhardt wrote:
So, am I to understand the NANOVNA-H tops out at 1.5 GHz? If so, what is the noise floor on an s11 measurement at 1.42 GHz? ================================================================== Dave, I think it is generally accepted that s11 return loss values less that 30 dB are the high water mark. On my NanoVNA-H I have a return loss of at least 30 dB up to about 1.3 GHZ. From there it falls off rapidly to 20 dB at 1.5 GHz. Actually, above 1 GHz, I only treat measurements as indicative, but still better than other equipment I currently own. I have not seen any performance reviews of the new ver 3.4 NanoVNA-H, but hugen says additional noise level improvement have been made. I believe erik has been part of that conversation. - Herb |
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Re: New NanoVNA-H just received
On Fri, Dec 27, 2019 at 01:32 PM, BruceN wrote:
¡ Am I missing something? I didn't a USB-C termination resistors. Maybe I don't know what I'm looking at..... ================================================ Bruce, You are not missing anything. Like the diode for battery level monitoring, the termination resistors are installed on-board and enable reliable usb-c to usb-c device connection (primarily NanoVNA-H to cellphone). That is the reason for the additional usb-c to usb-c cable in the accessory kit. - Herb |
Alberto I2PHD
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