开云体育

Buying is not a problem. Getting it from china to the US is a problem. A lack of available freight aircraft. I noticed that DeepElec has now gone to DHL for shipping rather than use the slow route. Since DHL has their own fleet rather than depending on passenger or cargo aircraft it may help a bunch.

Sorry not relavent here.

I receved one that reached india in march and no issues. .
I cut the outer cover and disposed off.

I am safe, so far. Lol

Sarma vu3zmv

On Mon, 18 May 2020, 4:03 pm Ron Spencer via groups.io, <ron.spencer=
[email protected]> wrote:

I'd think if you did a cal for the typical hf range of freq (1.8Mhz to say
30Mhz) you'd likely be OK. The swr reading may be off a little but when
tuning an antenna you're looking for the swr dip. The nanovna may show a
different swr than actual. As long as you understand this going in I'd
think you would be OK. It will be precise but not accurate.

I am hearing that some people are not able to buy NanoVNA units from China due to quarantine related issues... has anyone here encounterd this?

I'd think if you did a cal for the typical hf range of freq (1.8Mhz to say 30Mhz) you'd likely be OK. The swr reading may be off a little but when tuning an antenna you're looking for the swr dip. The nanovna may show a different swr than actual. As long as you understand this going in I'd think you would be OK. It will be precise but not accurate.

Hi Mark and Bob,

The real reason is: The NanoVNA, due to it's very limited internal memory,
has only 101 calibration points - by far not enough for a GHz wide frequency span:
Each point is some 10 MHz apart from the next. (Depending on frequency, this may
mean anything between short and open if you consider the frequency difference for
Lambda/4 - between two measuring (or cal) points, thus loosing needed accuracy.)
For example, 3.5 and 7 MHz all are between 0.1 and 10.1 MHz - enough for several
lambda/4 differences. Do the cal fpr just the süpan needed, say 3.5 ... 3.8 MHz, and
you are fine with your NanoVNA.

Usual Antenna Analyzers (like my RigExpert AA-600) have so many more points. So
the same precaution there is not needed. Read the manual for more detail.

That is also the reason, why calibrating (and measuring) with the Antenna analyzers
takes much longer accordingly. It is not only due to faster/slower ICs etc.

With regard to ...

On Sunday, May 17, 2020, 10:02:38 PM PDT, Mark Schoonover <mark@...> wrote:

"You don't have to keep recalibrating. Once done, you save the parameters and recall it each time.
Just do the calibration over the entire frequency range and you are done calibrating.
Bob"

This is only true, if you use some external software (like NanoVNA Saver) that overcomes
the 101 points limitation. (You will see that accordingly this takes longer, too.) For a solo
NanoVNA, however, Bob's statement imho is not applicable.

73, Hans
DJ7BA

-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von Mark Schoonover
Gesendet: Montag, 18. Mai 2020 07:02
An: [email protected]
Betreff: [nanovna-users] Nanovna vs Antenna Analyzer

Put my new nanovna-H4 to work this afternoon tuning up a new MFJ Cobweb.
Prett amazed at this $50USD device. Every time I changed bands I did a calibration. When I had an antenna analyzer I never had to do a cal. The analyzer I had did impedance as well as SWR. Why is this?

73! Mark KA6WKE

Website:




--
Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft.

Mark,

Bob is right, especially if you are doing measurements right at the NanoVNA connector. The interpolation of calibration points taken over a wide span works pretty well if connection lengths are short. Interpolation does not work so well when calibrations are done at the ends of relatively long cables. In those cases you will want to calibrate for the frequency span under use.

--John Gord

You don't have to keep recalibrating.? Once done, you save the parameters and recall it each time.
Just do the calibration over the entire frequency range and you are done calibrating.
Bob

Put my new nanovna-H4 to work this afternoon tuning up a new MFJ Cobweb.
Prett amazed at this $50USD device. Every time I changed bands I did a
calibration. When I had an antenna analyzer I never had to do a cal. The
analyzer I had did impedance as well as SWR. Why is this?

73! Mark KA6WKE

Website:

Thank you to all for the replies. I have purchased a NanoVNA-H4 from Gigaparts. It seems to be a pretty nice unit. It came in a deluxe box with three loads, two USB-C cables, two short SMA-terminated coax cables and a strap with a guitar pick looking stylus.

Now the learning begins.

I might add that it is not in a case.

On Sun, May 17, 2020 at 4:15 PM GEO BADGER via groups.io <w3ab=
[email protected]> wrote:

Hans,

I believe you may be correct. You've got sharp eyes my friend.

?___
Sent from my two way wrist watch
73 de W3AB/GEO?

On May 17, 2020, 12:28, at 12:28, hansfree <hans@...>
wrote:

IMHO you are both wrong...

The pictures show the VNA with the short and open screwed on. The load
is on one of the cables via a F-F adapter. As far as I can make up from
the pictures the set is complete. There is a list of items in the
details if you scroll down.

73's Hans PA3AZA.

--
Paul

W8SBH
?? ?? ????
(this too shall pass)

Hans,

I believe you may be correct. You've got sharp eyes my friend.

?___
Sent from my two way wrist watch
73 de W3AB/GEO?

Yes, I use mine to make HF and 2 meter antennas too.

WO4ROB, Rob

WO4ROB
________________________________
From: [email protected] <[email protected]> on behalf of hansfree <hans@...>
Sent: Sunday, May 17, 2020 12:22:07 PM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Are any of the NanoVNA sold on Amazon any better or worse than any others? Is there a better U.S. site to order from?

IMHO you are both wrong...

The pictures show the VNA with the short and open screwed on. The load is on one of the cables via a F-F adapter. As far as I can make up from the pictures the set is complete. There is a list of items in the details if you scroll down.

73's Hans PA3AZA.

IMHO you are both wrong...

The pictures show the VNA with the short and open screwed on. The load is on one of the cables via a F-F adapter. As far as I can make up from the pictures the set is complete. There is a list of items in the details if you scroll down.

73's Hans PA3AZA.

Thanks, Geo
I thought the connectors looked unusual in the photo.
I'm sure I already have the adaptors in my radio parts box.
I report back how this unit works when I get it.
All I want to do is measure SWR on HF and 2 meters for homebrew antennas.

Michael,

You'll need 2 SMA/F - SMA/F adapters to use that one.

?___
Sent from my two way wrist watch
73 de W3AB/GEO?

Here is the cheapest one I have ever seen on Amazon:



$24.89 on Amazon. It doesn't include an open or short terminator, only a 50 ohm. It does include cables.

I couldn't resist. I ordered one.

I am making a loop antenna very similar to the OM0ET model, but adding capacitors with switches to add the 60 and 80m bands. I used the nanoVNA to see the resonance and I achieved my goal but with very high SWR by adding the capacitors. Testing at RX confirmed these high losses. It seemed clear that the problem was due to losses in the added capacitors, but not due to excess voltage since it was with a small signal. I chose these 3kV capacitors because I was planning to use the enTX antenna as well and had them in the drawer. The loss had to be due to excessive ESR (critical in loop antennas) and I decided to try measuring it with the nanoVNA. I have ESR meters but they are for electrolytic capacitors, with much higher capacities and at much lower frequencies. I left only the Smith graph and chose a frequency of 3.65MHz. Previously I calibrated the nanoVNA in a small margin around. The measurement results confirmed an ESR of around 3.5 ohms in both normal and HV ceramic capacitors and an ESR of 100-200 milliohms in silver mica capacitors.
The results once the latter were assembled were great, both with the nanoVNA and with the receptor.
These measurements have been made with the nanoVNA-F (I have both) and I really liked that it started with the latest measurement configuration and its much greater autonomy. In bright sunlight, the screen was hardly readable like his younger brother's.
Cheers

Thank you, Larry and DiSlord. I must have read that 50 times, and it never got to my memory with out errors. Problem resolved.
Thanks, Glenn W3WTE

Just did the test

Two mixers rated for 2GHz-4GHz with IF ports 10MHz-2GHz
Connect the nanoVNA CH0 and CH1 to the IF ports, LO ports together to a generator at 2350MHz. Filter to measure connected to RF ports
nanoVNA span 100MHz to 300MHz
Filter is 2.5GHZ to 2.6GHz
S21 loss through mixers only 13dB
I would have expected some leakage through the connected LO ports but nothing visible
Loads of dynamic range , easy to check the filter. Works much better than I expected.
This is also a good approach to measure the performance of the up conversion to 1st IF, the 1st IF filter and the downconversion to second IF (just before the 2nd IF filter) of a dual conversion front-end such as used in a spectrum analyzer or general coverage receiver. Temporarily set the 2nd IF to zero Hz and the nanoVNA can do the measurement.








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