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Re: Measuring impedance at the bottom end of a ladder-line-center-fed wire dipole

 

Consider buying one of these

and use it between the nanoVNA and the ladder line (without your 1:1 balun). This will allow you to measure with best accuracy even if you have calibrated the nanoVNA with the standard calibration set.
Your 1:1 balun may not be optimal as the ladder line is 450 ohm and coax something like 50ohm (?)

To understand each impedance transformation connect the nanoVNA instead of the radio and switch to TDR mode.

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK


Re: F303 and 4" LCD for next generation NanoVNA #circuit #flash_size #improvement #enclosure #battery

 

For me the biggest issue with these has been the small display!,in the uk the f model is over ?100 as oposed to the h model at about ?30 ish,ive ordered a 3.2 inch screen for mine,not ideal but better than standard from the price point of view!.


Re: F303 and 4" LCD for next generation NanoVNA #circuit #flash_size #improvement #enclosure #battery

Ed Jones
 

Glen K4KV said: "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!"

I couldn't agree more. I would add to that list quality coax, connectors,
and calibration standards. At least as upgrade options. The first thing I
will do when I buy a NanoVNA is to upgrade all of these items anyway.
Thanks!


--
Ed Jones - K8MEJ - Lewis Center, Ohio U.S.A


Re: Measuring impedance at the bottom end of a ladder-line-center-fed wire dipole

 

Erik, thanks for responding.

For the moment, I'm just trying to understand what is going on, impedance-wise, with my antenna system. Not that I am having "problems" that need to be "solved," just curious.

When operating, I will have the following: 130+ feet of copperweld, hung about 60 feet up between two trees, center fed with about 100 feet of 450 ohm ladder line, connected to a 1:1 current balun, short coax run to a ground buss, short coax run from buss to tuner, coax from tuner to radio. I would like to understand what sort of impedance transformation is happening at each connection/through each element.


Re: Wait for V2 design or but current model on ebay?

 

On Fri, Dec 27, 2019 at 07:52 AM, hwalker wrote:
About the only other consideration I can think of is hugen has made some
worthwhile improvements which he has included in Version 3.4 of his PCB.
Was searching for info on the v3.4 improvements and found this from hugen79 at a Gidhub message exchange where he mentions at least one of the improvements:

hugen79 commented Nov 12, 2019: Noise problems introduced by USB connection I will use the new power chip in NanoVNA-H V3.4 to improve this problem. I will try to increase the capacitance of the si5351 to reduce noise. The problem of LED flicker noise can be improved by software.

Whole thread is here:


I assume most of those improvements might mostly have to do with reduced noise on the extended or upper frequency ranges? Since I would mostly be using it for 500MHz at most and much lower frequencies, perhaps I could get by for now with an older v3.3 board. Still be nice to have the latest revision.

In any case opened an Alibb account to be able to send M.King a message to ask if they might know of any ebay seller that has the most up to date v3.4 board in stock. Lets see what they answer. Thanks.


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


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*
<<< >>>/


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?


Re: F303 and 4" LCD for next generation NanoVNA #circuit #flash_size #improvement #enclosure #battery

GmailK4KV
 

Herb,

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:

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


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


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


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

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

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.
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



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

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.
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


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


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


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


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


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


On Line, Secure, Transactions

 

A suggestion, everybody.
Go to your bank and open another "chequing", er, "checking" account.
Tell the bank that that is to be a /debit card account/ and that it
is/not to be linked to your other accounts/. That is quite easily done.

Then transfer, say, $500 into that debit card account from one of
your "real" accounts. Thereafter use that account's card for all your
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.

Since there is never any more than $500 in the account and since it
is completely separate from your other accounts (different card number,
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.

Somebody putting an exact clone of that card into a cash machine and
using your p.i.n. will see the $500 balance or whatever the existing
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.

That has been done here. The account has been in use for a couple of
years now. The card is registered on Amazon, PayPal and Aliexpress and
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 PayPal
than give out my credit card. I also don't like the added postal charges for
expedient delivery.
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
--

May everybody have a happy and prosperous new year!
John
at radio station VE7AOV


Re: New NanoVNA-H just received

 

On Fri, Dec 27, 2019 at 05:40 PM, hwalker wrote:


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.
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)