开云体育

/?was told by a seller, when i asked about? the item showing up well before the projected date, and with/

/NO tracking information EVER, that he has to provide eBay with a tracking number to get paid. And so,
/

/everybody essentially gets a WRONG NUMBER. Maybe somebody can do a more in-depth search./

/I've ordered maybe 200-300 time direct and had virtually NO trouble other than some long times./

Bill


- - - - - - - -

Hi S Johnson,
bear in mind that there are multiple parties doing research and dev work;
edy555 who made the original NanoVNA, hugen who made the version that got
copied widely, and even the teams doing NanoVNA-F and the
as-yet-to-be-named "NanoVNA V2" - not to mention the people working on cal
kits, software, test boards etc.

The other obvious answer is: Price. ;-)

--
Rune / 5Q5R

Why would anyone buy any other than from Hugen? Support the one doing the research and dev work.

On Sun, 13 Oct 2019 at 14:41, W5DXP <w5dxp@...> wrote:

Someone said these $17 NanoVNAs are probably factory rejects (hopefully
only for a cosmetic blemish, e.g. a silk-screening error).

All I know is that the tracking number given to me for China post is
invalid. EBay says the label has been created, but certainly nothing has
moved. I am 99.99% sure that the $22 one I bought will never arrive, but I
am not fussed about it. I know that I will eventually get my $22 back.

I would have kicked myself had I not bought one, and they turned out to be
genuine, but I don’t think they will be.

Dave

--

Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

Well, I believe there is already a mobile app available for the NanoVNA?

Having a mobile version would be fine, and I'm not doing anything to
actively prevent it - ;-) - but I'm also not spending time actively working
on it while I have a long list of things I want to do with the PC version.
At least for now, I think supporting Windows, Mac and Linux is going to be
it for me personally.

--
Rune / 5Q5R

On Sat, Oct 12, 2019 at 09:13 PM, QRP RX wrote:

it looks strange, as I understand it worked well before upgrade. So it looks
like some settings issue.

Try to connect to your NanoVNA with terminal, for example PuTTY. type "help"
it should show you list of all supported commands, in such way you can check
that terminal connection is established successful. Then execute this command:

clearconfig

It will clean all settings to default state. After that power off and power on
device and check if your issue is fixed or not?

I've done that multiple times. I've loaded DMR's special touchscreen test firmware(#4778).
Same results. It's not the firmware. I've got a touchscreen that has become defective.

Thanks anyway.

On 2019-10-12 8:18 p.m., W5DXP wrote:

From: QRP RX: The loss in the cable due standing wave happens with poor impedance match between receiver/cable for RX and cable/antenna for TX.

A poor impedance match is usually a bad idea for coax but a conjugate match using low loss parallel feedline is often acceptable. For instance, according to TLDetails, the matched line loss for 65 ft. of RG8x at 7 MHz is 0.5 dB. The loss in 65 ft. of 600 ohm parallel line at 7 MHz feeding a 50 ohm load is 0.2 dB even though the SWR on the 600 ohm feedline is 12:1. The loss in the impedance matched RG8x with an SWR of 1:1 is 2.5 times the loss in the impedance mismatched (but conjugately matched) 600 ohm feedline with an SWR of 12:1.

In hopes of making things a little clearer to the newly arrived in

the world of r.f. energy transfer...

Electrical energy, including r.f., one can say can be moved in the

form of current or in the form of e.m.f., the "push" on the energy, the
voltage. (Of course, there is always some of each in any such transfer.)
The reason that 600 Ohm open wire line, above, is so attractive is that
the energy transfer is being made by voltage. Increasing voltage means
decreasing current and so decreasing I2R losses. High powered short wave
stations used open wire technique for that very reason, r.f. energy had
to be "transported" a long way to get out to the vast antenna farms such
stations used. 600 Ohm and 1,200 Ohm spacings were used.

It's the same reason that hydroelectric installations, distant from

the consumer city, "transport" energy in the form of voltage rather than
current. Very high voltage brings it's own set of losses from leakage
across thousands of insulators, corona and other effects. It is the
business of engineers to figure the best balance between the savings
from low current and the losses from high voltage in the design of a
particular long distance power line.

In a radio station where a random length antenna is in use, the

impedance at the antenna feed point can vary hugely. A tuner at the
transmitter can be adjusted to match whatever impedance is seen at the
transmitter end of the open wire line. The standing waves on the open
wire line involve little current and so the losses to I2R, as noted in
the post above, are inconsiderable.

John

at radio station VE7AOV

Hi

I just got a nanovna and I am trying to updagrade firmware from Aug 2nd to the latest in a W10 machine.
I boot up in dfu mode with the 2 pins shorted and white screen
W10 device manager shows smt32 bootloader under usb devices instead and the smt tool sw in the google drive does not recognise the device.
Perhaps I do not have the correct driver. Any suggestions?
I might try with the rpi3 b+ later otherwise.

73 Angel
M0HDF

#43 : On the Phase

@Gary O'Neil : Sun, Oct 6, 2019 at 04:45 PM
/g/nanovna-users/message/4194

Dear Gary,

We thank you very much, indeed, for this particular
comment:

"More precisely, any VNA measures amplitude vs.
frequency, and either measures or computes phase",

because -by one of the many positive side effects it
still has- it forced us to insist -as a challenge,
as usual : that is without resorting to any reference-
so that to finally remember -some minutes before-
that way -so simple, but forgotten- by which anyone
can expresses the Phase proving that the superposition
of two cosinusoidal waves of the same frequency is
indeed a cosinusoidal wave of the same frequency.

Therefore, once more : Please stay tuned !

Best regards,

73

nikolitsa oe3zgn|sv7dmc & petros oe3zzp|sv7bax @ arg iaoi nfi

43#

Hi Rune -

I'm not trying to convert anyone

Any consideration of mobile (iOS / Android) versions?
QT5 and Python are both supported on both, after a fashion...

Imagining that nanoVNA evolution forks,
a low-end Bluetooth dongle (picoVNA?)
could be cheaper with longer battery life
and UI focused on hosts where UI rules.

This is the unpacked picture, D2 is already installed, and the USB TypeC CC resistor is also installed. Thanks to Maggie for making a beautiful gift box for NanoVNA-H. Thru Adaptor is currently not delivered, and orders placed after October 20 will be replaced with new Thru Adaptors. You can now buy it from Maggie's alibaba store .
Due to my lack of production experience, in order to ensure the quality of the goods, delivery may be slow. Maggie uses DHL to ship, but some European customers have to pay a higher fee for DHL. If you need to change the courier, you can contact Maggie to modify it. If you use China Post, you can save $10 postage, but it is slower.
Feel free to contact me if you have any questions about NanoVNA.

hugen

On Sun, Oct 13, 2019 at 04:29 PM, W5DXP wrote:

For maximum power transfer, the impedance looking back down the transmission
line from the EDZ feedpoint needs to be 175+j1000 ohms, the conjugate of the
feedpoint impedance.

That's not true. If you have X not equals to zero, it means that load returns back RF energy. And it means that you have higher loss in the cable.

The thing that you're talking about is that coax cable can be used as impedance transformer. But coax transformer works due to standing wave. And standing wave make higher loss in the coax cable.

The maximum power transfer is achieved when X=0 and complex Z is equals for all components: Ztransmitter = Zcable = Zantenna. If some impedance is different, you will have higher loss.

I thought I gave all the info required to do the calculation.
The source is on github.
What else do you need?

KE8CPD,
Can you confirm that when you power up your NanoVNA that you see a battery icon, and that the CONFIG => VERSION menu shows 0,2.3. Just to confirm the upgrade is taking.


- Herb

Someone said these $17 NanoVNAs are probably factory rejects (hopefully only for a cosmetic blemish, e.g. a silk-screening error).

On 2019-10-12 11:32 a.m., David KD4E wrote:

Does not a mismatch create problems with loss and noise?

If I connect a 50 ohm coax to a 300 ohm TV antenna, without a
transformer, should I not anticipate a poor quality received signal?

David, just to deal with that exact example, commercial digital

television,...no.

Television stations, like other broadcasters, saturate their market

areas in signal so about anything will serve as an adequate antenna.
Just look at those rubbish "magic" all channel antennas that are peddled
by hard sell artists and that appear in peg board bubble packs! Their
sole technical merit is a complicated name yet they work fine within
stations' prime markets. A wire coat hanger would work just as well.

The second reason for "no" is that these days we are dealing with

digital technique. The margin in signal strength between a perfect
picture and no picture is very slim. Rather than noise, it involves
pixelation as the receiver struggles to assemble a proper display.

John

at radio station VE7AOV

Or am I misunderstanding?

David, KD4E

You know, after all the talk about matching impedances, I'm really

wondering .... we talk about POWER in watts but that's pretty much for

transmitters. But we talk about receivers in?? VOLTS. Well, okay,
microvolts,

usually. Somehow, I don't see a good reason to CARE about matching

receiver input impedance. Maybe it lowers the antenna bandwidth or Q?


Impedances have PHASE, but voltages do not. Care to comment?


Bill

--

Hi

OK, but from the table I can't see the feedback multisynth divider ratio. Indeed above 150 MHz the output multisynth divider ratio is fixed at 4 per Si5351A datasheet.

Bo

From: Starsekr: Bill, you get maximum power transfer when the impedance is matched.

Jim, according to the AC (RF) maximum power transfer theorem, you get maximum power transfer when the load impedance is *conjugately* matched. Luckily, coax with a Z0 of 50+j0 ohms is a trivial conjugate match to a 50-j0 ohm load. For a non-trivial example, the feedpoint impedance of an Extended Double Zepp antenna may be 175-j1000 ohms. For maximum power transfer, the impedance looking back down the transmission line from the EDZ feedpoint needs to be 175+j1000 ohms, the conjugate of the feedpoint impedance.

Ken,
You hit the nail on the head. At low frequencies, at VHF and down, I wouldn't worry about picosecond delays or femto-farad fringing C's. And I bet 99% of the Nano users will be looking at SWR only............no worries about the measurement plane.
I am mounting my Nano on a plate and adding N connectors with short cables connected to the plate to strain relief the Nano's connectors. This will give it a little more mass to deal with even the tugging of the USB cable:)
73

KE8CPD,
The group firmware repository below might be your best bet for locating the old firmware. Try the hugen or edy555 folders.

/g/nanovna-users/files/Firmware/All%20%28known%29%20publicly%20available%20NanoVNA%20DFU%20files%20from%20May%205,%202019%20through%20to%20Sept%2029,%202019

- Herb