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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.

On Thu, 26 Sep 2019 at 13:41, Rune Broberg <mihtjel@...> wrote:

Dr. Kirkby,
it does confuse me a little why you would buy a VNA from AliExpress, but
not a battery from Amazon. ;-)

I bought the NanoVNA from eBay - not that it makes much difference.

As long as ones expectations are correctly set - namely, to receive a
battery of an unknown capacity and quality, which might fail without
notice, but broadly speaking without catastrophic consequences, buying from
the sellers you mentioned should cause no particular problems.

Lithium ion batteries can fail with catastrophic consequences.

I know that the switch on the NanoVNA is of appalling quality, but I will
address that by an external switch.

The screen on the first NanoVNA I received was faulty - a problem Hugan
said is common.

A quick look found me this battery



a very reputable manufacturer, around 5 times the stated capacity of those
with the NanoVNA, at a cost of about 50% of the cheapest NanoVNA I have
seen.

I've seen no indications that the batteries sold on AliExpress or indeed on
Amazon should be any more dangerous than batteries bought elsewhere - and
given the price difference of roughly 10 times, the cheap batteries should
perform just fine for the average hobbyist reading this list and using a
NanoVNA.

I am certain that the capacity of the Chinese batteries on eBay are grossly
exaggerated - that’s based on tests I have performed. I don’t know about
reliability, having not done any tests, but I don’t trust cheap
batteries. Someone wrote in this thread his battery was bulging.

*Personally*, I would rather spend a bit more, get much higher capacity and
be more confident that the battery is of good quality.

*Personally* I don’t believe that the components of the NanoVNA are good
enough to use it without an external case. Therefore a physically larger
battery is not a concern to me.

Your recommendation to buy from a supplier for the *professional* market
does not particularly provide anything for the majority of us: Hobby users.

I don’t think the cost of a battery from a reputable manufacturer is that
bad for a hobby user, but ultimately these are personal choices. I did not
say any person must buy a battery from RS or Farnell, but just stated my
personal views.


--

Rune

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

On Thu, Sep 26, 2019 at 03:29 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:

I would *never* buy batteries from eBay, AliExpress, Amazon or similar.

I bought NanoVNA on aliexpress in this store:

It comes with battery - 602040 3.7V 450mAh. The battery includes protection module.
I tested it, NanoVNA works 2 hours from a fully charged battery.

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. Efficiency = good antenna is a matter of antenna
gain and resonance is only a small portion of it. A resonant short wave antenna in 1m
above ground will bring different results than one in resonance and 20m above. Both
of them will show a perfect SWR of 1:1 and other S-parameters, but the outcome ?

nanoVNA can only measure some technical parameters of your antenna - and they say
nothing about 'how good is this antenna' for receiving only ;-(

@erik@...:
/g/nanovna-users/message/3008

Hello,

First of all, allow us, please, to express, on the occasion,
our deep respect for your impressive Work with NanoVna.

Next, allow us, please, to inform you that just after the
message including the preliminaries of the uncertainty:

[6] : /g/nanovna-users/message/2968

we took into account your clear call for understanding
and thus we started a sequence of very short messages
on this subject, beginning with:

[10] : /g/nanovna-users/message/3043

Finally, allow us, please, to comment that, in our humble
opinion, regarding 'Understanding', there are the following
types of human beings, according their personal tastes:

(1) Those who don't want to understand, and those who want
to understand, but when they don't understand then, according
to their judging abilities, they put constantly the blame:
(2) on the others,
(3) on themselves, and
(4) either on the others or on themselves, according to the state
of their progress in the Knowledge

Keep up the Good Work !

Sincerely,

pez&yin@arg

13

Hi John,
thank you very much, and thank you for the kind description in your linked
post :-)

I assume you've calibrated on the NanoVNA? Or did you make an
in-application calibration? Either should be fine, of course.

Could I ask you to send me an exported S2P file of the data, please? I
would like to check how it looks.

I haven't previously seen a 10dB drop, and judging by the photo of the
filter on test, it doesn't show up on the NanoVNA itself. Can you verify
for me that it does not?

Thanks for reporting the problem!
--
Rune / 5Q5R