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Crystal measurement limitations


OwO 2021/07/03 02:16

Because of the design architecture of V2, the test signal is switched on and off at a few kHz. Crystals can settle slower than that, so results will be inaccurate when measuring crystals.
This applies to measuring crystals only, and doesn't affect SAW or other types of filters. This is also in the documentation and product descriptions.

The V2 Plus and V2 Plus4 firmware are actively maintained but the focus is on bugfixes and stability, and the changes required to support measuring crystals is tricky and experimental, so it will be released as a special firmware rather than be integrated in the default firmware. Officially, if you need to measure crystals, the recommendation is to use a V1 nanovna (edy555 version) or nanovna-f. I can assure you that the upcoming release of V3 does not mean V2 Plus/Plus4 are left unmaintained, in fact we still consider V2 Plus4 the main product (V3 is not expected to sell very much).

Lex PH2LB 2021/07/04 00:58

I own a V2 (first series) and as a hamradio homebrewer I had to find out the hard way before it was mentioned on the website. This is the reason why I advice not to go for the V2 models when you target is hamradio homebrewing because that often includes measuring and selecting crystals see : https://www.ph2lb.nl/blog/index.php?page=xtal-adapter-for-nanovna. ( https://www.ph2lb.nl/blog/index.php?page=xtal-adapter-for-nanovna )

What will the V3 version be different from in regard to the V2 series ?

73 to you and yours and stay safe.

Lex PH2LB

Rudi 2021/07/04 21:39

On Sun, Jul 4, 2021 at 11:06 AM, Lex PH2LB wrote:

>
> I own a V2 (first series)

Hello Lex,

With the ojisan firmware you can measure those parameters, see:
https://www.rudiswiki.de/wiki9/nanoVNA-V2-ojisanFirmware#LC.2C_Crystal_series_resonant_measurement

If you select the right frequency span, you get automatic the values for:
Fs
Fp
Ls
Cs
Cp
Rs
Q

I have also added the *screenshot funtion* to the ojisan firmware.
https://www.rudiswiki.de/wiki9/nanoVNA-V2-ojisanFirmware#Screen_capture

73, Rudi DL5FA

Lex PH2LB 2021/07/05 00:45

Hello Rudi,

Thank you for pointing it out. That would sorting out crystal much easier.

Will take a look at it.
--
73 to you and yours.

Lex PH2LB

Vladimir Lebedev 2021/07/05 01:20

Hello Lex!
See here https://groups.io/g/NanoVNAV2/topic/firmware_for_v2_it_contain/81847314?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,20,81847314
See screenshots from DiSlord

73 de Vladimir, dl7pga

Joe Smith 2021/07/05 06:55

I had written some software to characterize crystals after someone had asked me about making a custom filter from them.   I posted about the development here:

https://www.eevblog.com/forum/rf-microwave/fun-with-crystal-filters/?PHPSESSID=lnr626eqefd2d4ah3el0jeiat2

The last part of this video shows the basics of how to use it.   Of course, it is also covered in the manual.
https://www.youtube.com/watch?v=scZ3kZ4Q2sQ

While I ran various checks to see how accurate the setup is (other VNAs, pull method, RLC meters, checking known components) and others have replicated my tests, I have no idea of the absolute accuracy.  One thing is certain.  It will depend a lot on the operator.

The downside, while the software for the V2Plus4 has this feature, the VNA is not up to the task.  The upside, $50 solves that problem by simply buying one of the original NanoVNAs.  Really the better choice IMO for working below 300MHz anyway.

OwO 2021/07/05 07:14

There is now a release of the ojisankoubou firmware for the V2 Plus4 here:
ttps://groups.io/g/NanoVNAV2/topic/v2_plus4_ojisankoubou/83997806

Terry Nixon 2021/07/05 18:54

A Grid-Dip Meter, or Tunnel Dipper meter with a nearby frequency counter
works better for checking out crystals. I've been doing it for years.

On Sun, Jul 4, 2021 at 4:06 AM Lex PH2LB <lex@ph2lb.nl> wrote:

Tenko46T 2021/07/06 04:36

Hello Kyoko,

Oh, thank you for porting the ojisankoubou firmware to the V2 Plus4.
It's wonderful. This, at least for me, eliminates concerns about measuring narrowband Crystal filters.

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