开云体育

Hi Gyula - trying your website, I got an emoji with a zipper across the mouth and a message in Hungarian. Fortunately my google-translate has the camera option and told me that your website is down for maintenance. However I have visited before and you do have plenty of excellent info! Cpuld you post here when your site is back up? tnx!
--
72/73 de k1qed, ?bob.c ? ? ? ? qrp 4evr!

I have had a similar problem with one of my analyzers.?
It only likes relatively small memory cards.? ?Got any 1 or 2 gigs?
You really don't need anything as big as a 32 gig.
Kent WA5VJB

Aparently most newer cards do not work. I have tryed 11 different manufacturers SD 32 Gig cards and none of them work. Aparently You need one of the older style SD cards.
I found 2 older 16 Gig cards, and both work. I will still try other 32 Gig cards, but for now, will use the 16 Gig cards.
Clyde Lambert KC7BJE

CORRECTION: that was a VNA-64 (not 65) sorry.

Mike C.

Hi John,

FWIW, I purchased 2 units (tinySA and VNA-65) both from R&L and I am a happy camper. (i.e. no problems, your mileage may vary)

Mike C

Thank you - you've done a lot of work with the nanoVNA, it looks very interesting - Mark/K4LFL

I have been happy with my SAA-2N from R&L.
73, DOn N2VGU

But why would anyone want an RFID reader that can read cards over 10" away

My application is something like a bracelet antenna. Not spying. Lol. But as to the "short" calibration of the coil. According to an ST rep:

"The idea is to calibrate away the characteristics of the pickup coil, and be able to only sense the characteristic of the reader or tag antenna - since the antenna is still connected during the "short" calibration. A OSL calibration would only calibrate the VNA port + cable. The characteristic of the pick-up coil would overlap with the characteristic of the reader or tag antenna."

My nanoVNA has the OSL calibrations. And Through and Isolation calibrations. That's all. So, unless the "short" calibration of the coil can be arrived at via those and/or measurement methods, I guess I'm screwed.

John,
I have been entirely satisfied with the two SAA-2N units I bought from R & L.
--John Gord

Can you see more info on my site
--
Gyula HA3HZ ( )

I bought my Nanovna H4 from R&L and with the exception of not getting the
"open" calibration standard it has worked fine.I have heard that you don't
really need that calibration standard but they are sending me one.

On Mon, Jun 20, 2022 at 08:38 PM, Brian Donaldson wrote:

I'm not building an antenna. All I want to know is if the NanoVNA can show me
return loss peaks with a single length of stranded wire. Nothing more. I have
an antenna and it works just fine. Don't need an antenna.

If the NanoVNA cannot do a single wire return loss reading, then fine.

People are just mentioning that the VNA is transmitting very small amounts of power on that wire as if it was an antenna, and thus it will start behaving like one. You don't really have a choice if it does! And folks are pointing out that it's going to find an image antenna to work against, which is probably your "feedline" -- i.e., the VNA itself. If you are holding the VNA, like a handi-talkie it may use _you_ as the counterpoise!

Whether or not this affects the values, or to what extent, depends on a lot of factors. But, if you are measuring something then the recommendation is to know what you are measuring. This might be an opportunity to try different measurement setups.

Put another way: what is it that we expect to measure by looking at the S11 port reflection values along a single wire? It's not that it can't measure a wire, but rather what we expect from doing so, if not thinking of that wires as some electrical wavelength of an antenna?

Many thanks David. Your link does take me to a V2 group with posting this
month although not on the subject I seek. Some group identity confusion. I
was already subscribed to a V2 group (groups.io) but it indicates nothing
posted since May there.

Many thanks!

On Tue, Jun 21, 2022, 4:50 AM David J Taylor via groups.io <david-taylor=
[email protected]> wrote:

On 21/06/2022 09:01, John Reves WD8JLV wrote:

Also posted this on the V2 group but no activity there
since May so not sure how alive that group is.
Thanks in advance!

There was a post in the V2 group on 2022-Jun-16, so you may want to check
that...

/g/NanoVNAV2/message/3411

David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

On 21/06/2022 09:01, John Reves WD8JLV wrote:

Also posted this on the V2 group but no activity there
since May so not sure how alive that group is.
Thanks in advance!

There was a post in the V2 group on 2022-Jun-16, so you may want to check that...

/g/NanoVNAV2/message/3411

David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

I am totally new to Nano VNA and earning. Was planning to purchase a
NanoVNASAA2N from R & L Electronics. Then I discovered that Tindie seems to
be the "official" source of the V2's etc. Would appreciate hearing from
others here about R & L vs Tindie. Will I be making a mistake to buy from R
& L rather than Tindie? The price difference of about $100 would be a small
saving if I can expect to have problems with the R & L clone. Comments on
thus most welcome. Also posted this on the V2 group but no activity there
since May so not sure how alive that group is.
Thanks in advance!

On Tue, Jun 21, 2022 at 09:44 AM, igor-m wrote:

On Tue, Jun 21, 2022 at 02:38 AM, Brian Donaldson wrote:

I'm not building an antenna. All I want to know is if the NanoVNA can show

me

return loss peaks with a single length of stranded wire. Nothing more. I

have

an antenna and it works just fine. Don't need an antenna.

If the NanoVNA cannot do a single wire return loss reading, then fine.

Yes, nanovna will show you the resonance peaks in form of max |Z| in case of
EFHW antenna pretty well (see the picture in my previous post).

..

An EFHW is a single length of stranded wire, thus it should work with any
single length of stranded wire, imho.

Here are 2 pictures from my measurements - one with grounded nanovna during the measurement with a length of stranded wire put into S11, the second with nanovna not grounded. You may see the resonance peaks (where the |Z| is maximal) of the piece of wire are clearly visible on both. The wire is 15m up over a street.

On Tue, Jun 21, 2022 at 02:38 AM, Brian Donaldson wrote:

I'm not building an antenna. All I want to know is if the NanoVNA can show me
return loss peaks with a single length of stranded wire. Nothing more. I have
an antenna and it works just fine. Don't need an antenna.

If the NanoVNA cannot do a single wire return loss reading, then fine.

Yes, nanovna will show you the resonance peaks in form of max |Z| in case of EFHW antenna pretty well (see the picture in my previous post).
I did it many times with various EFHW antennas. Simply put the wire into the S11 and watch |Z| in ohms.
The peaks of max |Z| perfectly fit the real impedance and minima of swr of the wire when used with the 1:XX impedance transformer. I've been using a multitap unun where the taps are selected based on that impedance measured by nanovna and the swr is at minimum there.
An EFHW is a single length of stranded wire, thus it should work with any single length of stranded wire, imho.

"End fed" antenna vs. "EFHW" - here the people usually happily mix the types of antennas:

1. The "EFHW" is an END FED HALF WAVE DIPOLE, fed from an END by a HIGH impedance, HIGH voltage source, in the point of a LOWEST current and a HIGHEST voltage at the dipole. See my |Z| picture to see the impedance seen by nanovna - those resonant peaks are in range from 6000ohm to 1000ohm. A counterpoise is not needed with well made EFHW as the feeding point is the highest impedance one and the currents there are pretty SMALL. Usually the length of coax from the unun/transformer to the TRX works as a "grounding" well (from my experience 3-4m of coax will do).

2. People say "End Fed" also when talking about a "long wire", "random wire", "quarter wave wire or vertical", or "quarter wave multiples wire", etc - those are not EFHW antennas and they DO require a well made counterpoise. Their feeding point could be of any impedance (the "long wire" or "random wire") or pretty low (5-80ohm) with quarter wave or ground plane antennas (those are not end fed half wave antennas but actually dipoles fed in the MIDDLE - in the point of LOWEST impedance and HIGHEST currents).

I thought this was a fair question, so I tried it. I laid out about 8 ft of
stranded wire about 16-18 AWG. Poked a few strands into a female SMA
coupling. Connected that to about 4' of RG-316, which was attached to my
nanoVNA. I did a scan of 50Mhz to 500Mhz. I could see multiple SWR dips on
the screen. The first was at 56.75 Mhz, so I guess it works.

On Mon, Jun 20, 2022, 21:05 Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

On Mon, Jun 20, 2022 at 05:38 PM, Brian Donaldson wrote:

I'm not building an antenna. All I want to know is if the NanoVNA can

show me

return loss peaks with a single length of stranded wire. Nothing more. I

have

an antenna and it works just fine. Don't need an antenna.

If the NanoVNA cannot do a single wire return loss reading, then fine.

Measuring Return Loss means you are sending power to something and
measuring the power returning back to the source. Then the calculation can
be made.

You can't calculate RL to a single wire just suspended in the air. You
either need a ground reference or another wire in order to get current
flow. In both of these cases an antenna is being constructed, it will
radiate and it will have resonant frequencies. You can measure the RL at
the connection point to the wire and the other side (ground or wire).
Changing the length of the wire, the ground conditions or other wire
characteristics will result in different RL measurements.

If the wire suspended in the air has another one running parallel then you
have a transmission line instead of an antenna. Connecting a load on one
end and you can measure RL at the other.

Roger

Mark, Great news! The person that put that document together did a phenomenal job.I think the name "beginners Guide" may deter many who are in fact very knowledgeable?to perhaps assume the document will have little value to them. However, the document?holds such a tremendous amount of reference information I believe it's of value at most?every level. The absolute beginners guide is truly an outstanding piece of work.

Your antenna works because the radio metal case, power cord and the shield of any accessories connected to the radio are acting as a counterpoise. You don't have a free space antenna setup.

Mike N2MS