开云体育

Hi Maurizio that's probably what is happening here although the new sweep freq was within the range that the cal covered.

Ideally (hint to Rune!) the software would contain a "Zero the sweep" button that would set the active trace (S21 in my case) to zero regardless of the cal data, freq range, etc.

Hi all,
please find attached a dynamic range test of the NanoVNA with several DC-18GHz precision SMA attenuator.
Prior to the test I performed a fresh calibration.
I think the result leaves some room for discussions!

73, Norbert, DG1KPN

On Thu, Sep 26, 2019 at 08:37 AM, John AE5X wrote:

Hi John , the VNA Agilent ( like hp8753D hp8720 hp8510C ) that I used at work , when you change parameter of frequency sweep
used during the CALIBRATE procedure , turn off the ACTIVE CALIBRATION. For some parameters like IF Filter , Output level , Average counts , the VNA put a warning " the CALIBRATION mybe incorrect ".
73 de IZ1MDJ Maurizio

Thanks guys - I got it corrected and have posted the new result to the link
listed above. The fix was that I have to recall the saved cal data each time I
change the sweep. I calibrated the nanoVNA on the device itself, not via the
software - I will re-cal within Rune's program and see if that makes any
difference in whether or not the cal data is applied even after changing sweep
frequencies.

Here is a shot of where I see 10 dB loss (where there should be none with both
ports connected together) even though I did perform a RESET prior to the cal:



73,

John

On Thu, 26 Sep 2019 at 16:30, <qrp.ddc@...> wrote:

My shipment is delivered with air mail. So, it seems like your seller
provided you with false information. He just sell devices with no battery.
:)

It is tricky to *legally* ship batteries - in particular lithium ion
batteries, especially as an individual or small company.

When my company ships VNA calibration kits, we always put “Contains no
batteries. No radiation” on the export documents, in an attempt to avoid
problems.

When I buy very small lithium batteries from Farnell, it will come in a box
with hazardous labels on the outside, and say it should not be shipped if
damaged. I can buy much more dangerous items, like 5 litres of acetone from
eBay, and there will be nothing on the packaging to indicate the contents
are dangerous.

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

@ qrp
Thank for the info.

I got NanoVNA with 3.7V 450mAh >battery It has code 602040 and no other
identification. But NanoVNA works 2 >hours from it.

Seller did mention right information (without battery) & i opted for it
because of restrictions from customs dept. for clearance of items with
battery.

On Thu, Sep 26, 2019, 9:00 PM <qrp.ddc@...> wrote:

On Thu, Sep 26, 2019 at 08:44 AM, Praveena NG wrote:

my first nano vna and does not contain internal
battery due to shipment restrictions.

I got NanoVNA with 3.7V 450mAh battery It has code 602040 and no other
identification. But NanoVNA works 2 hours from it.

My shipment is delivered with air mail. So, it seems like your seller
provided you with false information. He just sell devices with no battery.
:)

On Thu, Sep 26, 2019 at 11:14 AM, <erik@...> wrote:

I helped to get the TDR improved and that required the 256 point FFT

it's better to perform 32768 points IFT for TDR. But I suspect it will not fit into the chip memory :)

On Thu, 26 Sep 2019 at 16:35, Dr. David Kirkby <
drkirkby@...> wrote:

SWR and resonance are not the same thing. An antenna can be resonate but
have a VSWR of 100:1. Another antenna may have a 1.5:1 VSWR, but not be
resonate.

What I meant to say is that changing the system impedance doesn’t change
the efficiency of the antenna. You change the efficiency by changing its
losses.

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

Thanks guys - I got it corrected and have posted the new result to the link listed above. The fix was that I have to recall the saved cal data each time I change the sweep. I calibrated the nanoVNA on the device itself, not via the software - I will re-cal within Rune's program and see if that makes any difference in whether or not the cal data is applied even after changing sweep frequencies.

Here is a shot of where I see 10 dB loss (where there should be none with both ports connected together) even though I did perform a RESET prior to the cal:



73,

John

On Thu, 26 Sep 2019 at 15:10, Wolfgang OE1MWW <oe1mww@...> wrote:

David,

yes, SWR (resonance) is fairly pertinent for an antenna. But once again,
this does not
say, if this is a good antenna or not.

SWR and resonance are not the same thing. An antenna can be resonate but
have a VSWR of 100:1. Another antenna may have a 1.5:1 VSWR, but not be
resonate.


Efficiency = good antenna is a matter of antenna

gain and resonance is only a small portion of it.

Efficiency of an antenna has nothing whatsoever to do with resonance. A
lossless dipole of 0.5 wavelengths long has an impedance of around 73 + j
42 ohms, so is not resonate. However, the dipole is 100% efficient as it is
lossless.

The efficiency of an antenna is

(Power radiated) / (Poor accepted by the antenna)

If you have an antenna with a very high SWR, it will not radiate much. But
neither will it absorb much power.

Note also that an antenna with an impedance of 75 ohms will have a VSWR of
1.5:1 in a 50 ohm system, but 1:1 in a 75 ohm system.

I base my above comments on
145-2013 - IEEE Standard for Definitions of Terms for Antennas



You can get a copy without payment using sci-hub.


G8WRB.
--
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

On Thu, Sep 26, 2019 at 06:04 PM, <pluto@...> wrote:

this is the replacement OEM joystick recommended on the wiki

Thanks for info.

Is it safe to solder it with heat gun? It seems that the plastic parts can be damaged.

On Thu, Sep 26, 2019 at 08:44 AM, Praveena NG wrote:

my first nano vna and does not contain internal
battery due to shipment restrictions.

I got NanoVNA with 3.7V 450mAh battery It has code 602040 and no other identification. But NanoVNA works 2 hours from it.

My shipment is delivered with air mail. So, it seems like your seller provided you with false information. He just sell devices with no battery. :)

Mouser has a 600 mAh Renata ICP622540PMT for $17.79 (USA only) and I might buy that, since I know it will be good, if I can't find a cheap MP3 player with a suitable battery in it.

Bear W5VZB

this is exactly the document that I had read, thank you

HI qrp.ddc,

this is the replacement OEM joystick recommended on the wiki:
this one is also recommended on the wiki:

I added a Goggle translated user guide (NanoVNA_manual _ch045) to the "Files" section of this group. Full credit and appreciation go to Hiroh Satoh (user "ch045"). The untranslated version can be found at .

Hiroh's guide covers the TDR, touch calibration, and DFU upgrade capabilities of the recent firmware upgrades. He has added some much needed screenshots to his user guide and an example of tuning an antenna for lowest VSWR. The latter is the primary reason a lot of hams purchase the NanoVNA in the first place.

Again, many thanks to Hiroh for sharing this user guide with the community.

Herb

Bruce,
I added the full Goggle translated user guide (NanoVNA_manual _ch045) to the "Files" section of this group. Again, full credit and appreciation go to Hiroh Satoh's (user "ch045").

Ok, thanks

I'll focus on transmitting then as it generally goes that an antenna thats good for transmitting on a certain band will also receive on that band ;)

John,
The first step before performing the OSLT (Open-Short-Loa-Thru) calibration is to select "RESET" under the CAL menu. Neglecting to do this can result in the -10dB offset you are seeing.

@Reginald Beardsley via Groups.Io :
/g/nanovna-users/message/2927
/g/nanovna-users/message/2948

Hello,

Allow us, please, to point out that frankly we are not
sure if the messages on this very topic, as well as,
the references especially included at:

[7] : /g/nanovna-users/message/2984

cover to the slightest your expressed interests, so,
let us know, please, accordingly, taking into account
that this is the current state of published research
on this subject, excluding some papers under
preparation in order to be published in our small
journal:



Once again, thank you very much for your interest
in our work !

Sincerely,

pez&yin@arg

14

the only issue that I have with NanoVNA bought on aliexpress is the switch (joystick). It seems that I got defective joystick, because it is often triggers push when I'm trying to make right turn. The seller said that he send replacement joystick, but he didn't provided tracking number. So, I suspect I may not get replacement.

If you know where to buy replacement joystick please let me know.